# Understanding Distal Taper



## Kippington

There's a lot of variation in kitchen knives when it comes to distal taper. The topic tends to get glossed over and the details get heaped into one narrow definition, so hopefully this thread will help explain some of the more subtle characteristics of a good taper.





First we should cover what taper looks like from the spine. It can be broken up into three sections - The grip area, the middle of the blade and the tip.

*Grip (neck, choil and handle) area*

The grip area, or the part of the blade that goes into the handle is the first part we should pay attention to with regards to taper. It's often measured as the spine thickness of the neck, or the thickness of the spine above the heel.

There are three reasons why you would want this to be the thickest part of the blade, the first being comfort. A thicker spine is more comfortable to hold as it allows for more surface area to push down on with your hand. Many cheaper knives (such as Kiwi knives) have extremely thin spines in this area. These make it uncomfortable to push down while cutting through harder foods, as all the force going back up into your hand gets concentrated through a narrow surface.
Similarly, the thickness of the choil down to the cutting edge will influence the comfort of your finger in that area during forward push-cuts. The dreaded Wusthof/Sabatier style full-bolster was designed specifically for this reason, to expand the choil area and increase the thickness where you grip the knife. Other knives will reverse this idea, and have the spine thickness drop dramatically where your finger goes into the choil, while still maintaining a high degree of thickness at the neck.



_A full bolster maintaining neck thickness down the choil, plus an example of the reverse_

Another reason is strength: Many cheaper mass-manufactured knives will have the neck thickness the same as the spine above the heel of the blade. This creates a stress riser at the neck - on thin knives in particular - where the knife is weaker and more flexible at the neck when compared to the stiffer heel and handle on either side of it. Jobs such as crushing garlic with the side of your knife will concentrate forces into the neck, making it more likely to bend in the case of a san-mai/honyaki or crack with a fully hardened blade.




The last reason applies mostly to hidden tang knives with no bolster. A hidden tang can only be is thick as the spine going into the handle, and we want the thickest tang we can possibly get to help increase strength and mitigate any rust that may have been caused by moisture getting into the handle. A thicker neck/spine helps facilitate this improvement, which in turn increases the lifespan of the knife.
Carbon steel knives are more susceptible to rust, but stainless knives are definitely not immune to this phenomenon. A rusty hidden tang, particularly a thin one, is a disaster waiting to happen.



Now it could be argued that some of these points are not part of the distal taper and have more to do with the handle. However, understanding the thickness at this junction helps to explain why distal taper further down the blade is considered to be a positive attribute in kitchen knives.

*Middle area*

So taking everything above into consideration, it would seem like we want a super thick spine, right? Well _*no*_, obviously a thick a blade will easily get wedged in food during a cut. Naturally we want something thinner in the area where we do the cutting, so we'll need to transition the thick spine of the handle area into a thinner middle section of the blade. There are many ways to do this, it can be done drastically or gradually, and through concave, convex or linear means. We can also use a combination of any of these three methods to create a compound taper.



_(a) No taper and the thinnest grip area of the four, (b) straight/linear taper, (c) concave taper, (d) convex taper_

As with all things relating to knives, there's a balancing act going on with taper in the middle of the blade. Any positives you might get out of one style will probably increase a negative property, depending on how you look at it. There are four things to take into consideration: _Food separation, food release, flexibility _and_ balancing point_.

Thinner cross-sections (in conjunction with the grind) can have better food separation and possibly improved food release over a thicker one - more on that below. That said, thinning the cross-section of a knife requires the removal of steel which in turn increases flexibility and removes weight. This can count as a negative thing for some people, as the removal of too much steel can cause a knife to feel whippy and flimsy, as well as sending the centre of balance back towards the handle. Some makers mitigate this by forming a taper at the grip until the blade reaches a certain thickness, then stopping the taper altogether to form an essentially taper-free blade from the middle to the tip. This is an example of one of the many variations of a compound taper, and Kato's style is a good showcase of this.




*Tip area*

For gyutos, the way a taper ends at the tip is very simple - The thickness of the spine transposes into the grind at the area where they meet. Some people reference sideways slices (e.g. parallel cuts to the board on onions) with the tip of the knife as an indicator for good taper, but really the thinness of the grind is the thing doing the work. You could also use a nakiri to do the same sideways cuts, only the tip of the knife doesn't end at a point. It should be said, having a point can help due to having less surface area in contact with the food, and the lower blade height at the tip means the average thickness of the grind goes down as the spine heads towards the edge, but this doesn't have as much to do with the taper as it does the grind and profile shape.

One important thing to note is that knives with super thin tips will have a lot of flexibility in that area. Some people really dislike any flexibility at all, others don't notice it and might even prefer it for it's related positive attributes (e.g. thinness for sideways cuts).
You can actually test how thin the tip of a knife is by balancing the knife on your finger just behind the centre of mass towards the handle and allowing the tip of the knife to bounce off a hard surface. Thicker tipped knives will clunk but the thinner ones will bounce, giving a surprisingly good indication of how well a knife will perform during the sideways cut.

*Taper and balancing point*

There are many things that determine the balancing point of a knife, and taper can be one of the more influential factors. If you prefer knives with more forward balance (towards the tip) you'd do well to look for knives with taper that maintains thickness from the neck into the middle of the blade. People that prefer handle-balance should go for extreme taper, and there's obviously an endless amount of possibilities of anything in-between.

*Taper and grind/food release*

We hear people say that a choil shot can often be an inaccurate representation of the grind of a knife, and the presence of a taper is one of the reasons why.




Here is an example of four grinds, each with the same angle at the edge. They may look very different, but it's possible to have all of the four cross-sections occur at different points across the same tapered bar of steel.
The first one on the left is essentially a full-flat grind, known for some of the worst food release possible. As we move right you can see the spine getting thinner, which causes the shinogi line to move down the blade. The example on the far right is where the spine is quite thin and the shinogi has moved down near the bottom of the blade. As you might imagine, the ability for food to stick to the smaller bevel decreases with the shrinking area of contact. This means that the far right example has both better food release and less wedging in food. It's difficult to argue against two advantages like that, so some knife makers create a thick spine in the handle area and drastically shrink it way down as soon as it's out of the grip of your hand. This would be another example of compound taper.




So, that pretty much covers it.
Thanks for reading guys. let me know if you have any questions.


----------



## IsoJ

Excellent write up. There was answers to many of my questions and easy to read, I didn't need to Google or translate.


----------



## captaincaed

Dude...
Can I just add how much I appreciate your CAD drawings. Hand drawn stuff is often the norm, and crisp visuals make the conversation 1000% better


----------



## dafox

Great write-up, thank you.


----------



## labor of love

I’ve often wondered if there is an ratio for ideal distal taper. Should a knife regardless of thickness above the choil be 10x, 15x or 20x thinner 1cm from the tip?
Even though we don’t have a universal ideal, maybe using a ratio can help with classification of the extremity of the taper, right?


----------



## Kippington

labor of love said:


> I’ve often wondered if there is an ratio for ideal distal taper. Should a knife regardless of thickness above the choil be 10x, 15x or 20x thinner 1cm from the tip?
> Even though we don’t have a universal ideal, maybe using a ratio can help with classification of the extremity of the taper, right?


It's a cool idea, but I don't think you can scale the ratio up or down like that. The ideal taper on a thicker knife might cause an unusable tip on a thinner knife if made to the same ratio.


----------



## Barmoley

Great write up. I am glad you pointed out balance effect of distal taper, this is an often overlooked area when people talk about distal taper.


----------



## Corradobrit1

labor of love said:


> I’ve often wondered if there is an ratio for ideal distal taper. Should a knife regardless of thickness above the choil be 10x, 15x or 20x thinner 1cm from the tip?
> Even though we don’t have a universal ideal, maybe using a ratio can help with classification of the extremity of the taper, right?


Probably too many variables but I bet there are some fairly good guidelines that can be gleaned from such a formula. I now have a better appreciation of my Kato's and the decision making that was taken to arrive at the various Standard and WH styles. For Wa handle knives the thick spine is far more comfortable. It appears Will Catcheside has given this some thought too.

Excellent writeup.


----------



## labor of love

Are you saying that thicker knives have more room at the spine for larger ratios? And applying these larger ratios to thinner spines(at the choil) would produce a tip that’s just too thin?
If so, I agree. The most recent mazaki batch had a 5.75-6mm spine at the choil. But then at the tip was very thin. Whatever ratio the knife had couldn’t be replicated with a 3.5mm spine over choil. But to me, this is an example of too much distal taper. My shigehiro gyuto also has quite the workhorse spine, but it feels like a workhorse in cutting from spine above choil to the tip, but with distal taper.


----------



## Carl Kotte

Thanks kippington! This was awesome!


----------



## captaincaed

So what runs through your head when you see a super thick tang such as a Jiro? I imagine future thinning would affect the balance quite a lot. Anything else stand out?

Also true on the Kiwi. Lived in Thailand for a while and kept some around. Even tried to round the spine for comfort. Ultimately got rid of every one. They make great Som Tam but damn they're hard to get used to after using better Japanese knives.

Mazaki is killing it in the taper department. I think it's one of the best grind and taper combos for the price right now


----------



## labor of love

I’m probably in the minority here. Lots of people probably do want a tip ground to a particular thinness without regard to spine thickness over the heel.
My thinking is that I ultimately favor a heavier knife to cut like such from heel to tip. Which is why I think a ratio of some sort would help me understand my own preferences.


----------



## Barmoley

I prefer a heavier and stiffer knife too. The problem I have with extreme taper is that the knife changes the way it cuts depending on which portion of the blade is used. If the extreme taper is uniform through the blade the portion closer to the handle has a drastically different grind than the middle. You could get a two knives in one type of a situation, which some might like, but I prefer consistency through most of the length of the blade. This is not very noticeable when the taper is not extreme or when spine and blade closer to the edge taper at different rates.


----------



## SeattleBen

Thank you for the clear and concise write up. I'll also throw in for the appreciation of non hand drawn drawings as being more clear.


----------



## ian

labor of love said:


> I’m probably in the minority here. Lots of people probably do want a tip ground to a particular thinness without regard to spine thickness over the heel.
> My thinking is that I ultimately favor a heavier knife to cut like such from heel to tip. Which is why I think a ratio of some sort would help me understand my own preferences.



As you say, there's no ideal notion for distal taper, since it depends on user preference. But part of the problem with using a single ratio even to classify taper is that you have to decide where to measure. A single number (basically, the slope of the taper) would work if the taper was always linear, but it's hard to capture the shape of an arbitrary paper with a single number. The usual set of 4 numbers is useful, though.

Here are a bunch of example measurements from JKI. I'll include width of spine at handle/heel/middle/1cm from tip, in order, and in mm. All 240mm gyutos.

Gengetsu: 3.85, 3.23, 1.78, .51
Kochi Migaki: 3.93, 3.47, 2.48, 1.08
Kochi KU: 5.15, 3.9, 2.1, .8
Heiji: 4.17, 3.73, 2.55, 1.53
Ginga: 2.23, 2.23, 1.96, .75
Ginrei (Shihan): 3.38, 3.07, 2.85, 1.21
Kagekiyo (Wh #2): 3.62, 3.79, 2.88, .69
Uraku (Stainless): 2.45, 2.45, 2.22, 1
Hinoura (Ajikataya): 4.7, 3.39, 2.74, 1.81
Blazen Ryusen: 3.66, 3.43, 1.9, .91
Ittetsu (Wh #2): 3.49, 3.47, 2.82, 1.57

Just from these numbers you can tell what the shape of the taper looks like.


----------



## labor of love

But, if you notice the knives with the most dramatic distal taper from spine above heel to mid point of blade are also the same knives with the most dramatic taper from spine above heel to tip.
To me this means the mid point measurement is simply obeying the distal taper that is decided by the ratio between tip thinness and above the heel thickness so I concern myself more with those 2 measurements


----------



## jimmy_d

Wow thanks for the write up! A lot of great info in here.


----------



## labor of love

My contention is that perhaps knowing a ratio between spine thickness at heel and tip for our favorite knives may lead to some insight into knowing which knives might be our favorite knives (on a personal level) and why that may be. 

Hope I didn’t derail a great thread.


----------



## M1k3

Great write up and pictures. Looking forward to the one on grinds and profiles


----------



## Kippington

M1k3 said:


> Great write up and pictures. Looking forward to the one on grinds and profiles


But I already did one on profiles!


----------



## Marek07

@Kippington Thank you for your continuing _*edumacation*_ of the masses.


----------



## Corradobrit1

Barmoley said:


> I prefer a heavier and stiffer knife too. The problem I have with extreme taper is that the knife changes the way it cuts depending on which portion of the blade is used. If the extreme taper is uniform through the blade the portion closer to the handle has a drastically different grind than the middle. You could get a two knives in one type of a citation, which some might like, but I prefer consistency through most of the length of the blade. This is not very noticeable when the taper is not extreme or when spine and blade closer to the edge taper at different rates.


Theres a subtle inflection in the grind of the Kato WH towards the thickest part near the handle just in front of the choil. Impossible to see in pics but easily picked out when manipulated in the right light. This helps to retain a far more modest taper along the blade road in the lower portion of the convex grind above the edge.


----------



## thebradleycrew

captaincaed said:


> Dude...
> Can I just add how much I appreciate your CAD drawings. Hand drawn stuff is often the norm, and crisp visuals make the conversation 1000% better


+1


----------



## ian

labor of love said:


> My contention is that perhaps knowing a ratio between spine thickness at heel and tip for our favorite knives may lead to some insight into knowing which knives might be our favorite knives (on a personal level) and why that may be.
> 
> Hope I didn’t derail a great thread.



I think this is on topic! I also think that the ratio of spine thickness at the heel to spine thickness at the middle is a good number to look at. It just doesn’t capture the full picture. Here’s an updated spreadsheet:






(The above is a picture I took with my phone of a screenshot I took on my computer. What do you want... I was in a rush and confused.)

Above, I’ve included not just the thicknesses in mm, but the ratios between the various thicknesses. The knives are ordered by the heel/middle thickness, ie your measure of taper.

Some takeaways:

1) Gengetsu and Kagekiyo have screaming thin tips. The taper from middle to tip is much more dramatic than from heel to middle. Note the huge difference in middle/tip vs heel/middle. Also, the Kagekiyo doesn’t even have a huge taper heel/middle... it’s middle of the road in that respect, even though the final taper is the most extreme of all. On the other end, Heiji has a fair bit of heel/middle taper, but not much middle/tip taper.

2) Most tapers aren’t actually linear all the way to the tip. The Heiji is maybe the closest, but middle/tip is always bigger than heel/middle. Of course, maybe it could be linear up till 2 cm from the tip or something, but that’s not included in the data. It would be nice to have more measurements for each knife.

In any case, though, if you look at the spreadsheet, there’s not much relationship between the second to last column and the last column. Again, though, maybe all this says is that people often grind the tips thinner no matter what, and when we’re talking about “taper” we should more be talking about what happens in the first 210mm of the knife, rather than at the tip.


----------



## Nemo

captaincaed said:


> Mazaki is killing it in the taper department. I think it's one of the best grind and taper combos for the price right now



From this, I'm guessing that you haven't tried a Kippington yet?


----------



## Nemo

Great write-up Kip.

But you didn't need to break your mate's knife just to demonstrate a stress riser [emoji16].


----------



## labor of love

I couldnt disagree more! I guess we're just concerned about different things. The difference in spine thickness at middle blade could vary quite abit, but what im saying is that .5mm difference is a much profound thing at the tip than at the mid point. But should we disregard mid blade thickness? Nah, but I keep it on the back burner.
When we talk about "good distal taper" we're implying there is a good bit of distal taper happening therefore heel area of the blade will be beefier right? And the tip area will be thin right?

So Gengetsu and Kagekiyo have screaming thin tips? But what kind of cutting experience would those gyutos have if they are 5mm thick at the heel? The weight of the blade wouldve shifted quite abit to the rear of the blade. Can the weight of a heavier blade create more force on the tip area and make the tip area fragile if the tip area is crazy thin? Yep. So with keeping a good distal taper but also keeping a tip away from being fragile theres something there, a balancing act.
Maybe, a ratio

But all this talk about distal taper with regard to spines is kinda of isolating. Much of what happens with cutting and feel has more to do with how weight, grind, measurements relate, how it all relates.

Im using distal taper discussion as a proxy for weight distribuition in some ways, also I just dont like workhorse knives with laser tips


----------



## ian

labor of love said:


> I couldnt disagree more! I guess we're just concerned about different things. The difference in spine thickness at middle blade could vary quite abit, but what im saying is that .5mm difference is a much profound thing at the tip than at the mid point.


 Absolutely!


labor of love said:


> But should we disregard mid blade thickness? Nah, but I keep it on the back burner.


 Not so sure about this. If you only have 3 measurement points, I feel like middle of the blade thickness will more accurately reflect what’s happening in most of the knife than thickness at the heel or tip.


labor of love said:


> When we talk about "good distal taper" we're implying there is a good bit of distal taper happening therefore heel area of the blade will be beefier right? And the tip area will be thin right?
> 
> So Gengetsu and Kagekiyo have screaming thin tips? But what kind of cutting experience would those gyutos have if they are 5mm thick at the heel? The weight of the blade wouldve shifted quite abit to the rear of the blade. Can the weight of a heavier blade create more force on the tip area and make the tip area fragile if the tip area is crazy thin? Yep. So with keeping a good distal taper but also keeping a tip away from being fragile theres something there, a balancing act.
> Maybe, a ratio


 Agreed!


labor of love said:


> But all this talk about distal taper with regard to spines is kinda of isolating. Much of what happens with cutting and feel has more to do with how weight, grind, measurements relate, how it all relates.
> 
> Im using distal taper discussion as a proxy for weight distribuition in some ways, also I just dont like workhorse knives with laser tips



Yea, me neither. I actually found it disconcerting to use one beefy Mazaki I had for this reason (and other reasons).

I’m sorry, I must have misinterpreted what you were saying previously. All I was saying above is that you can’t rate distal tapers based on one number like (heel thickness / middle thickness), or (heel thickness / tip thickness), and that it’s more complex than that. This is what Kip is saying too, I guess, when he talks about the different types.

It was interesting to see all the data in the table together, though!


----------



## captaincaed

Nemo said:


> From this, I'm guessing that you haven't tried a Kippington yet?


I haven't, I've basically missed every BST post. Does he take orders?


----------



## Nemo

captaincaed said:


> I haven't, I've basically missed every BST post. Does he take orders?


Yep.

Not sure how long his wait list is at the moment though.


----------



## Corradobrit1

labor of love said:


> also I just dont like workhorse knives with laser tips


Whats your definition of workhorse? I always assumed it was a beefier, more robust knife, especially along the spine. I now discovered quite the opposite, at least wrt Kato's STD vs WH.


----------



## labor of love

Corradobrit1 said:


> Whats your definition of workhorse? I always assumed it was a beefier, more robust knife, especially along the spine. I now discovered quite the opposite, at least wrt Kato's STD vs WH.


Oh yeah-I just mean big fat azz knife with big fat azz spine.


----------



## labor of love

Is there a diff in taper between standard and workhorse Kato? I’ve only used the workhorse versions.


----------



## HRC_64

labor of love said:


> Is there a diff in taper between standard and workhorse Kato? I’ve only used the workhorse versions.



There was a picture of a Kato workhorse next to a Kato Santoku (or whatever) 
and the latter didn't taper very much...of course, nobody really tapers a santoku


----------



## HRC_64

naval architects have been working on 3D tapers for 100 years,
here's a convex and wide bevel equivalent hull diagram


----------



## Corradobrit1

labor of love said:


> Is there a diff in taper between standard and workhorse Kato? I’ve only used the workhorse versions.


Definitely. I think it was Maksim who even said it. I'll try and dig up the reference.


----------



## labor of love

Corradobrit1 said:


> Definitely. I think it was Maksim who even said it. I'll try and dig up the reference.


Oh it’s okay. Should’ve tried the standard instead of workhorse back in the day.


----------



## Corradobrit1

HRC_64 said:


> There was a picture of a Kato workhorse next to a Kato Santoku (or whatever)
> and the latter didn't taper very much...of course, nobody really tapers a santoku


Not just the tip. The entire length of the blade shows less taper.


----------



## McMan

Corradobrit1 said:


> Not just the tip. The entire length of the blade shows less taper.


which is which?


----------



## labor of love

I wonder if Gyuto has better taper than that Santoku thing.


----------



## Kippington

Nemo said:


> Yep.
> 
> Not sure how long his wait list is at the moment though.


Thanks. It's something around 6 months, maybe a bit more.
Depends on how much time I spend writing posts instead of making knives! 
_____________

After getting some sleep I've remembered there's some more interesting stuff to add to the topic.
The effect of taper on:

The hamon
Pattern-welded Damascus
Centre alignment of the cutting edge
I'll write them later as bonus material.


----------



## Corradobrit1

McMan said:


> which is which?


WH on left. Both have pretty similar edge lengths


----------



## Carl Kotte

Kippington said:


> Thanks. It's something around 6 months, maybe a bit more.
> Depends on how much time I spend writing posts instead of making knives!
> _____________
> 
> After getting some sleep I've remembered there's some more interesting stuff to add to the topic.
> The effect of taper on:
> 
> The hamon
> Pattern-welded Damascus
> Centre alignment of the cutting edge
> I'll write them later as bonus material.



Bonus material! This just keeps getting better. You’re like a kitchen knife Santa Clause and David Attenborough in one person.


----------



## captaincaed

6mo beats bloodroot 52mo


----------



## Corradobrit1

captaincaed said:


> 6mo beats bloodroot 52mo


I know what i would choose and not just because I don't have to wait an eternity. Thats Maumasi and Rader wait times.


----------



## suntravel

Imho distal taper above the edge ist more important than on the spine. On the spine ist is good for comfort to have it thick at the handle and thin in the front so ist will not get stuck in big veggies.

For cutting i prefer grinds from 0,6 - 0,8mm 1cm above the edge in the front, goning to 1,3-2mm 1cm above the edge on the heel.

So for pushcuttig or rockchopping the blade starts easy to slice in the food, and as you push forward, short before it is cut through a little weging starts bending the food away from the blade instead of sticking to it.

Regards

Uwe


----------



## labor of love

suntravel said:


> Imho distal taper above the edge ist more important than on the spine. On the spine ist is good for comfort to have it thick at the handle and thin in the front so ist will not get stuck in big veggies.
> 
> For cutting i prefer grinds from 0,6 - 0,8mm 1cm above the edge in the front, goning to 1,3-2mm 1cm above the edge on the heel.
> 
> So for pushcuttig or rockchopping the blade starts easy to slice in the food, and as you push forward, short before it is cut through a little weging starts bending the food away from the blade instead of sticking to it.
> 
> Regards
> 
> Uwe


You’re bringing in cutting ability into a conversation about distal taper of a spine. So yeah, the way a knife cuts obviously is more important than spine measurements.


----------



## suntravel

Distal taper can occur not only at the spine, could be in the complete grind 

If you compare a Blazen with an Migaki, Blazen is with distal taper only on the spine but not on the grind, Migaki no taper on the spine and none on the grind.

Both are cutting almost equal, but the Blazen gives you more comfort in the hand.

So only looking at the distal taper on the spine tells not the complete story 

Regards

Uwe


----------



## labor of love

So what youre saying is that the way the thickness above the edge tapers from heel to tip might be relevant? Mind blown.


----------



## Kippington

suntravel said:


> Blazen is with distal taper only on the spine but not on the grind


You're saying the Blazen's spine gets thinner towards the tip, yet the grind remains completely unaffected by this? This makes no sense to me.
If the spine gets thinner down it's length. the primary bevel will have to get smaller too - either by height or by angle. By my reckoning, this would be called a tapered grind.


----------



## suntravel

On the Blazen up to 1cm above the edge it has the same thickness above the edge, above that it it getting thicker to the heel on the last 1/4 of the blade.

But for cutting performance up to 1cm abve the edge is the most important part.

Regands

Uwe


----------



## Kippington

So let me get this straight - by your definition, the 'grind' starts at the edge and ends 10mm above it?
Any change above 10mm is to be considered distal taper?


----------



## suntravel

Any taper from the heel to the tip is a distal taper, but its effect on cutting performance depends on in which height above the edge it occurs.

Regards

Uwe


----------



## Kippington

I will try asking again. Your definition of the 'grind' starts at the edge and ends 10mm above it?


----------



## suntravel

The grind is where a blade is grindend, parts of the geometrie can als done by blacksmithing.


----------



## Kippington

Okay, so the grind is where the blade is grinded.
The grind on the Blazen goes up to the spine.




Yet you say:


suntravel said:


> Blazen is with distal taper only on the spine but not on the grind


I think your definitions are a bit loose.


----------



## suntravel

maybe the grind near the edge is more percise


----------



## Kippington

Yes, thank you.
This thread was created to help people better understand distal taper. Some of the things you said made it more confusing.


----------



## ian

As I understood it, Uwe was just saying that thickness of a knife is not just a function of distance along the edge, but of height above the edge as well, and he gave an example where the taper along the spine didn’t predict the taper closer to the edge. The content of what he was saying seems noncontroversial. But it’s true that muddying the terminology makes conversation difficult. Thanks again for the great thread.


----------



## HRC_64

There are mulitple cross sections of a hull or a knife that taper from heel to toe...This is why the sailboat people are miles ahead of the knife people talking about this kind fo stuff.

Please don't be arrogant about this, its FACTS.

Distal taper means the taper in a plane as viewed from above, not the taper of the spine itself.
In other lines of work...eg if you've ever had a medical scan... 

this is also called called the 'coronal' plane. as you take slces in the coronal plane from top to bottom, the shape is differnt, whch reflects the taper (heel to toe) and grind (spine to edge).

'Distal' is what you call the view lookign down on the spine of a fish, or an animal with a horizontal to earth spine, but its an anatomical medical term. In a human that walks upright that is called 'coronal' place (as in "Crown") looking down, but its same thing.

It is quite common with sailboats that the waterline is the most critical areaa, wheres the "line" of the hull at the top (sheerline), and the keel line (edge) are really much different areas in how the affect performance.

For knife performance, like sailboats, the spine (or sheerline) really doesn't matter that much (ITSELF) for performance,
IMHO, and it is relevant primarily because it correlates with the cross sections much lower down the blade.

BTW this is another area that the correlation =/= causation distinction is useful to think thru more generally

Cheers.


----------



## Kippington

ian said:


> As I understood it, Uwe was just saying that thickness of a knife is not just a function of distance along the edge, but of height above the edge as well, and he gave an example where the taper along the spine didn’t predict the taper closer to the edge. The content of what he was saying seems noncontroversial. But it’s true that muddying the terminology makes conversation difficult. Thanks again for the great thread.



Yes, Uwe is talking about a valid observation.
It's important to get the terminology correct because he's talking about a single property that can be described in more than one way. This property has been talked about in-depth in other threads. I decided not to bring it up here because it can be covered under the category of _'the grind'_ but might add confusion if filed under _'distal taper'_ as well.

Here are some pictures from an old thread to help illustrate what I mean.









We should all be able to agree that these two examples have the same *spinal* distal taper, shown in yellow. It can also be said that the grind on both knives is tapered as it goes towards the tip, because the bevel on the top knife decreases in angle and the bevel on the bottom one decreases in size.

Here's the thing, both of the following statements are true and sum up the same property:

*The difference between them is in distal taper below the spine:* The top knife has more internal distal taper
*The difference between them is in the grind:* The top knife has a more acute grind towards the tip
So if both statements represent the same thing, the question is: _Which description would you prefer to use?_
Uwe chose the former and mixed up his definitions on the latter, making the two sound like completely separate topics.
I'd rather call it a difference in the grind, which keeps the definition of distal taper easier, and it also means I didn't have to mention any of this in my original post. But alas... here we are.


----------



## ian

Yea, your original post was great. If you'd mentioned everything there, it would have been too confusing. The simplicity is what made it so readable. It's good to have these remarks later in the thread for those that are still paying attention, though.


----------



## captaincaed

Both grind and taper affect overall shape, I really like the ‘two equivalent statements’
Sometimes you need to break a topic into parts to wrap your head around what happens when all the factors combine.
Of course it’s that subtle combination that creates the things we all get so excited about.


----------



## HRC_64

The one area this is really critical is at the tip...

If you think of the dista taper of a knife not as a single variable X
but as a vector of X1...Xn (with each X measured say 1mm belwop spine at heel)

Some certina things come into play:

1) The Tip is dropped below the spine
2) The distal taper at Xn=at the tip is not the same as X1=spine
3) The level of drop to the tip impacts the section of taper that includes the tip
4) Therefore, it follows that the "from above view" taper of a knife if directl impacted by the drop of the tip
5) The spine isn't the most relevant plane for measure (or evaluating) taper by any means

Distal taper viewed from above equaling "spine taper" is in one sense an optical illusion, although in another sense its "literally true"
because the spine is dropping to meet the tip. 




But not separating out what is happening (multiple tapers are interacting) in mulitple dimensions
can cause us to overlook the way the knife grind+taper interact.


----------



## LostHighway

HRC_64 said:


> There are mulitple cross sections of a hull or a knife that taper from heel to toe...This is why the sailboat people are miles ahead of the knife people talking about this kind fo stuff.
> 
> Please don't be arrogant about this, its FACTS.
> 
> Distal taper means the taper in a plane as viewed from above, not the taper of the spine itself.
> In other lines of work...eg if you've ever had a medical scan...
> 
> this is also called called the 'coronal' plane. as you take slces in the coronal plane from top to bottom, the shape is differnt, whch reflects the taper (heel to toe) and grind (spine to edge).
> 
> 'Distal' is what you call the view lookign down on the spine of a fish, or an animal with a horizontal to earth spine, but its an anatomical medical term. In a human that walks upright that is called 'coronal' place (as in "Crown") looking down, but its same thing.
> 
> It is quite common with sailboats that the waterline is the most critical areaa, wheres the "line" of the hull at the top (sheerline), and the keel line (edge) are really much different areas in how the affect performance.
> 
> For knife performance, like sailboats, the spine (or sheerline) really doesn't matter that much (ITSELF) for performance,
> IMHO, and it is relevant primarily because it correlates with the cross sections much lower down the blade.
> 
> BTW this is another area that the correlation =/= causation distinction is useful to think thru more generally
> 
> Cheers.



I'm not sure that I entirely understand what you are pointing toward here. I'll happily stipulate that boat design/hydrodynamics as well as aerodynamic research may offer useful points of reference for enhancing our vocabulary and possibly some framework conceptual understanding. Perhaps that is all you are suggesting? I'm not persuaded that they ultimately add much to our ultimate understanding of how a knife functions. The direction of force, mediums, and a number of other criteria/variable are all vastly different.
I think Kippington is doing some really great work here. The limitations of language, the absence of hard data, and perhaps some differences in knife "feel" preferences are all things that we are struggling with.


----------



## captaincaed

As far as (sail) boats, my basic understanding is that they're built to have multiple lines where the hull meets the water. Major lines could be :

Boat at rest, upright, maybe slowly motoring
Under sail and heeled over, optimized for speed in racers although I couldn't say how exactly
Ass down nose up when motoring fast (hull speed)
As a sailboat goes faster, it actually sinks in the water and kicks its nose up to create a longer water line (where the hull meets the waters surface). If you try to pull a sailboat with a displacement hull beyond hull speed, it will sink just going straight forward. A planing hull (flat bottom skiff) has nothing to fear.

This is all to imply, I guess, that a really well designed knife has a lot of factors to consider and several strategies to get closer to great design. And of course be task specific. You'll never race a house boat, and you don't want to live on a racer a day longer than you need to.


----------



## HRC_64

LostHighway said:


> I'm not sure that I entirely understand what you are pointing toward here. I'll happily stipulate that boat design/hydrodynamics as well as aerodynamic research may offer useful points of reference for enhancing our vocabulary and possibly some framework conceptual understanding. Perhaps that is all you are suggesting? I'm not persuaded that they ultimately add much to our ultimate understanding of how a knife functions. The direction of force, mediums, and a number of other criteria/variable are all vastly different.
> I think Kippington is doing some really great work here. The limitations of language, the absence of hard data, and perhaps some differences in knife "feel" preferences are all things that we are struggling with.



First of all, if you think this is about hull design your just wrong. Its about geometry. Especially the geometry of 3D objects and how this is drawn (rendered) in 2D space. Hull design is a well established field with respect to technical drawing.

In particular, it deals with 

1) tapering shapes that are wider in back and narrower in front
2) tapering shapes that taper from (deck) top to bottom (keel)

There is a well established convention of drawing these complex shapes,
which is required because they are complex.

Talking about the "distal taper" of a boad hull makes no sense,
because there are multiple planes w/ tapers that are relevant 
...from deck to keel, etc


----------



## HRC_64

captaincaed said:


> As far as (sail) boats, my basic understanding is that they're built to have multiple lines where the hull meets the water.



The water line is the water line--water is flat plane 
(this is why "above sea level" is used on topography maps)

The boat is not always in the water in the same way,
because of the forces of the wind on the sail,
and the water on the hull.

But the earlier point was a general point,
which is the water line is not the deck-line.

The water line is important because
thats where the hull contacts the water,
as a practical matter.

With respect to food, and knives,
this is like saying the part of the knife
that touches the food is most critical.

However, solids are not liquids,
and knives are not buyant, so 
the idea of a "waterline" isn't the 
relevant idea.

The revelvant ideal is that there is a 
"business" part of the cross section,
that part that sees the most impact with food,
and this is not the part the farthest asway from the edge.

Arguably, its the longest tapered cross-section, 
which is one that includes the tip and the heel.

Whether or not this is a diagonal or a horizontal
etc is very debatable but its definitely closer to the 
edge than the spine.

This general comment was made earlier and prematurely dismissed,
which is why I tried to articulate the same point using differnt language.


----------



## ian

...

I’m all about off topic digressions in general, but maybe enough with the boats already?


----------



## captaincaed

ian said:


> ...
> 
> I’m all about off topic digressions in general, but maybe enough with the boats already?


Agreed


----------



## HRC_64

ian said:


> ...
> 
> I’m all about off topic digressions in general, but maybe enough with the boats already?



Again, its about drawing tapers in 3D space...has nothing to do with boats.

Other than people that talk about boats know alot more about the subject
than people who talk about knives.

Its not worth trying to explain it to you any further.


----------



## HRC_64

captaincaed said:


> Agreed



LMFAO


----------



## HRC_64

To summarize, geometry 101

3D tapers occur (are measured) in reference planes
knives have mulitple refernce planes

The taper of a knive is a SET of tapers/reference planes, not a single "thing"


----------



## ian

I appreciate references to geometry, being a mathematician whose research area is geometric topology. But it seems like the whole point here is that you can measure distal taper at different distances from the edge (or, fine, also in different planes if you tilt the knife). And all this was already discussed above, and the paragraphs on paragraphs about boats don’t contribute anything new. It was interesting to note that people in the nautical world also care about distal taper, but maybe let’s leave the conversation at that...


----------



## ian

HRC_64 said:


> Please don't be arrogant about this,



...



HRC_64 said:


> First of all, if you think this is about hull design your just wrong.





HRC_64 said:


> Its not worth trying to explain it to you any further.





HRC_64 said:


> LMFAO


----------



## suntravel

To make clear what i meant by dont judge a knife by the distal taper on the spine...

Spine of the Blazen has a significant distal taper on the spine, but not where you are cutting most times with. And this ist the only drawback of this great knife for my taste.

From my understanding Blazen is a full length laser, the one below a workhorse with lots of distal taper in the cutting area.






Regards

Uwe


----------



## labor of love

There we go throwing around terminologies again. Blazen is not a laser.


----------



## suntravel

labor of love said:


> There we go throwing around terminologies again. Blazen is not a laser.



Do you have an Takamura Blazen?

And which serial knife will cut more laserlike ? I know only 3 cutting with less effort...

Regards

Uwe


----------



## HRC_64

labor of love said:


> There we go throwing around terminologies again. Blazen is not a laser.



Alot of r2 knives have very little distal taper and relatively thin, AFAIK they rarely get over 2.5mm thick on the spine.
There was a discussion about this recently talking about abrasives and they are hard/expensive to grind or something.

I think its safe to say he's using laser as shorthand for "thin" knife spine, and doesn't speak english as a primary language.

From the chart, it seems there is very little taper along the axis of the knive that goes from the heel to the tip.


----------



## HRC_64

suntravel said:


> And which serial knife will cut more laserlike ?



People here to mean "very thin knife with almost dead-flat grind" and some blazens have enough choil-shape to argue about this designation. although I'm uncertain how reliably conformist these knives are in general (it seems over time the grinds have evolved depending on the year, etc)

Its not right/wrong is just social conventions constraining the usage of "slang" word.


----------



## suntravel

I have an Takamura R2 Migaki also with 1.6mm at the spine, and well the 300mm Blazen is going a bit more laserlike trough the food, thin spine is not all you need for cutting with very litte effort 

Most extra thin Ashis can not compete 

I also have build an device for measuring the pressure with pushcutting, to take out the feel from a heavy knife....

Regards

Uwe


----------



## labor of love

HRC_64 said:


> Alot of r2 knives have very little distal taper and relatively thin, AFAIK they rarely get over 2.5mm thick on the spine.
> There was a discussion about this recently talking about abrasives and they are hard/expensive to grind or something.
> 
> I think its safe to say he's using laser as shorthand for "thin" knife spine, and doesn't speak english as a primary language.
> 
> From the chart, it seems there is very little taper along the axis of the knive that goes from the heel to the tip.


Anyone that’s used a Blazen could tell you right away that the thickness and cutting experience is miles apart from what we’ve come to understand as Sakai lasers.


----------



## suntravel

labor of love said:


> Anyone that’s used a Blazen could tell you right away that the thickness and cutting experience is miles apart from what we’ve come to understand as Sakai lasers.



I have never seen an Ashi to cut better than my Blazen, of maybe + 30 ones i have tested, Yusuke extra thin could compete, Orca also but what else?

All Konos or Dois could not compete...

And have you tested an fresh Takamura Blazen or not 

Regards

Uwe


----------



## labor of love

I don’t know which Blazen you’re talking about. I’m referring to the blazens that are currently in production. This shouldn’t even be up for debate.
Takamura is a whole different ballpark based on the ones I’ve owned.


----------



## labor of love

Just look at the specs.
https://www.japaneseknifeimports.com/collections/blazen/products/blazen-ryu-240mm-gyuto
it’s a has plenty of tapering in both directions.

Either you’re misunderstanding terminology on accident or you’re a very elaborate troll.


----------



## Nikabrik

@Kippington, that was a fantastic write-up. thanks for sharing.


Kip's remarks, and those of others, have shown that the way a knife bends is important. Since I'm a big fan of quantifying these things, I thought an analytical look at this might be interesting. What I'll be discussing is bending of cantilevered beams.


Ignoring material properties, bending of beams is governed by two things: bending moment, and area moment of inertia (a/k/a second moment of area). Bending moment, which is symbolized by M, is essentially fancy talk for "torque". It's the product of force and leverage. Area moment of inertia, symbolized as I, is a property of a cross-section that represents its stiffness. I'd like to look at curvature, which quantifies the tightness of a curve, and is the inverse of radius. Curvature is represented by k; k=M/I.


The simple case that is relevant here is a cantilevered beam loaded at the free end. We'll treat the handle as the cantilever support point, and the tip as the free end. Obviously in use, that's not exactly accurate, but it's still useful for our purposes.


In this sort of bending, moment is at its maximum at the handle, and decreases linearly, reaching zero at the tip. As a result, a rectangular shape with no taper in thickness (ie, no change in section) will bend the most at the supported end - with curvature decreasing linearly to zero at the tip. That's obviously undesirable, and only the case in really low-end cutlery. Here's a graph illustrating this - curvature is in arbitrary units, and I've left the tip off the curvature so that we don't get into division by zero weirdness later:







However, once we add distal taper, we shift the curvature. Profile will have an impact, too, but it's a weaker effect, and we're not talking about profile right now. In particular, the area moment of inertia depends on w*t^3, where w is the blade width, and t is the blade thickness. Because the thickness is cubed, it has a far stronger effect on stiffness.


In fact, you can taper so thin that the tip bends more than desired, as has been described int his thread. However, it should also be possible to taper a knife just right so that the curvature is not concentrated at the handle, but also is not excessive at other points. To illustrate, I've made some graphs - again, not considering profile.


Here’s lots of taper:






Here’s a bit less taper, gradually increasing and dropping off at the end:






Here are two more, with progressively less taper:











You can see that as we decrease the taper, the curvature at the handle is sneaking back up. A stepped taper will mitigate that:







Speaking of steps - we could also see the needed increase in thickness of the tang base on the width change - but the blade grind begins to have an effect, since tangs are not usually beveled.

Just to reiterate - this is all ignoring change in width and cross-section, and the tip shape will significantly increase flex over what I've graphed. However, I think the body of the blade will adhere fairly closely to what I've shown, for typical gyuto profiles.


----------



## M1k3

https://arons.no/nettbutikk/65-takamura-blazen/


----------



## suntravel

The Blazens are a cooperative design to build the best cooking knife from the Echizen Uchihamono, some are grinded from Ryusen ( the only ones availible now ) and others from Takamura (all sold out)

I am talking about the Takamura Blazen, not the Ryusen ones 

But anyway real lasers are custom made, i have never seen a japan made one that could beat the thinnest grinds from Robin Dalmann for example, but the thinnest grind is not allways the best for a pro chef 

Slow easy fun cutting ist an other cup of tea than to do a lot of prep under time pressure 

Regards

Uwe


----------



## Eloh

@labor of love 
Why don't you just explain the terminology in detail instead of just "throwing it around" yourself.
The takamura blazen I had was definitely what I personally would refer to as a laser. With a little more distal taper at the spine compared to a typical sakai laser, but from cutting experience it's def laserlike, wich was exactly his point: the distal taper at the spine is not that important when there is no distal taper in the middle and bottom of the blade.

Also your link is a ryusen not a takamura


----------



## suntravel

labor of love said:


> Just look at the specs.
> https://www.japaneseknifeimports.com/collections/blazen/products/blazen-ryu-240mm-gyuto
> it’s a has plenty of tapering in both directions.
> 
> Either you’re misunderstanding terminology on accident or you’re a very elaborate troll.



You call me troll without even having a Takamura Blazen in your hands ?

How does with go to gether with calling yourself Labor of Love 

Regards

Uwe


----------



## labor of love

Eloh said:


> @labor of love
> Why don't you just explain the terminology in detail instead of just "throwing it around" yourself.
> The takamura blazen I had was definitely what I personally would refer to as a laser. With a little more distal taper at the spine compared to a typical sakai laser, but from cutting experience it's def laserlike, wich was exactly his point: the distal taper at the spine is not that important when there is no distal taper in the middle and bottom of the blade.
> 
> Also your link is a ryusen not a takamura


He most certainly didn’t say Takamura Blazen in the post I’m responding too. I can’t read his mind.


----------



## suntravel

I wrote Takamura sevreral times, and for a one with good knowlege about knifes the mark on the balde in my pic will show thats an Takamura also 

Regards

Uwe


----------



## labor of love

Maybe work a little harder on the words you use so people can actually understand what you’re saying 

citing one of many older blazen knives that are no longer in production and acting as if it’s understood is just ridiculous 

at a glance takamura and blazen look quite similar


----------



## HRC_64

I think the laser comment was just an aside and nit-picking it doesn't add to the discussion about distal taper. 

Lets go back to diagram of the Blazen:

The one question I had is "why" do they grind it like that? 
Is it easier to OEM or is there some reason (robustness?)?

I wonder if the knife would bend/break or something if not
thicker up front than witha "proper" (proportionate) distal taper?


----------



## suntravel

Maybe try to answer dircet questions....

Have you ever cut with an Takamura Blazen or not 

Tough that will not change what they are, lasers with no distal taper above the egde 

But very good knifes also for my taste, just not perfect, as my english writing 

Regards

Uwe


----------



## suntravel

HRC_64 said:


> I think the laser comment was just an aside and nit-picking it doesn't add to the discussion about distal taper.
> 
> Lets go back to diagram of the Blazen:
> 
> The one question I had is "why" do they grind it like that?
> Is it easier to OEM or is there some reason (robustness?)?
> 
> I wonder if the knife would bend/break or something if not
> thicker up front than witha "proper" (proportionate) distal taper?



Yes it is easy to grind, making a distal taper above the edge is some what complicated.

a thinner tip is also more fragile, but with an bit wider bevel to the tip also strudy enough for pro use.

Regards

Uwe


----------



## Eloh

labor of love said:


> He most certainly didn’t say Takamura Blazen in the post I’m responding too. I can’t read his mind.



The thing is it's Completely irrelevant to the point he was trying to make about different kinds of distal tapers since he offered a picture with discrete data points to make his point pretty clear, wich you ignored.

Its all good though. We should all try harder to not misunderstand each other., especially when we have a whole lot of people here who don't have English as their first language.


----------



## labor of love

Eloh said:


> The thing is it's Completely irrelevant to the point he was trying to make about different kinds of distal tapers since he offered a picture with discrete data points to make his point pretty clear, wich you ignored.
> 
> Its all good though. We should all try harder to not misunderstand each other., especially when we have a whole lot of people here who don't have English as their first language.


I also agree, Suntravel should use illustrations and photos in the future as his words fail him.


----------



## Eloh

.. Talking about trolling


----------



## ipq7

labor of love said:


> I also agree, Suntravel should use illustrations and photos in the future as his words fail him.



Or we just switch from English to another language


----------



## labor of love

Eloh said:


> .. Talking about trolling


Are you really arguing that the very words hes using arent pernitent to the point hes making? Thats hilarious. Im ready to drop this whenever youre ready to.


----------



## suntravel

labor of love said:


> I also agree, Suntravel should use illustrations and photos in the future as his words fail him.



made already but maybe just not suffient like direct simple questions 

Regards

Uwe


----------



## labor of love

Sorry Kippington.


----------



## ipq7

Guys, can we pls return to the distal taper rather then blaming and shouting on others? 

I just came across this topic and must admit I like it.


----------



## ian

labor of love said:


> Sorry Kippington.



It's all good. Now people years from now looking for good information about distal tapers will also get an honest picture of our human struggles on KKF. This is an archaeological record.


----------



## labor of love

ian said:


> It's all good. Now people years from now looking for good information about distal tapers will also get an honest picture of our human struggles on KKF. This is an archaeological record.


I eagerly await all the PMs I will receive in 2023.


----------



## Matus

There is no excuse to use a misunderstanding as a reason to attack anyone, nor is it particularly nice to belittle others because of their less-then-perfect language skills. There are plenty non native English speakers around here - should they all be afraid to share their opinion or join discussion because someone might put them down? 

Back on topic. I like distal taper (I mean a gyuto here) where the neck is nice and thick, then it gets progressively thinner to around where the heel is, followed bz a gentle taper over the most of the length of the blade and then gets again more pronounced last few centimetres towards the tip. Roughly speaking. I expect a taper to the grind from the heel towards the tip, but I have not used any gyuto worth picking up that would not have one.


----------



## Kippington

HRC_64 said:


> Lets go back to diagram of the Blazen:
> 
> The one question I had is "why" do they grind it like that?
> Is it easier to OEM or is there some reason (robustness?)?
> 
> I wonder if the knife would bend/break or something if not
> thicker up front than witha "proper" (proportionate) distal taper?


I explained why they grind it like that at the end of my first post.

Don't forget, you are comparing the consistent grind angle of the Blazen to knives that have a changing primary bevel angle. The tip of the Blazen is no thicker than any other part of the knife.
The hypothetical reverse of your question would be, "Why does the bevel angle of the bottom knife deviate so much?"


----------



## HRC_64

Kippington said:


> Don't forget, you are comparing the consistent grind angle of the Blazen to knives that have a changing primary bevel angle. The tip of the Blazen is no thicker than any other part of the knife.



Kip thanks for confirming the Blazen's "consistent grind angle" as per the photo (talking choil-shot type cross sections). 
But the question remains WHY is this an objective of the maker?

EG, one option would be to have more of a convex ("U") shape at the back and "V" shape at the front...
ie, the spine still the same or pretty close since U and V are about the same across the top.

I suppose one explanation is "blazen has a mediocre grind" because of cost savings and a desire to be durable.
Both of those are potentially useful in a Pro Environment since aforability and durability both are relevant.

But it may also be underwhelming from a character or performance perspective.

Variable cross section geometry at first glance require more skill to execute (and be more costly), 
and would lead to a weaker tip, but perhaps may give a more intersting performance for some users?

It also seems, mathematically, variable grind geometry woud also induce distal taper into the knive at lower reference planes than the visible/optical taper. 

This also illustrates a discussion of grinds vs tapers done in isolation is tricky.


----------



## suntravel

Kippington said:


> "Why does the bevel angle of the bottom knife deviate so much?"



Simply because it ist made to have a distal taper above the edge 

Also there is no simple bevel angle, its complete convexed.

Regards

Uwe


----------



## Kippington

suntravel said:


> Simply because it ist made to have a distal taper above the edge


You are going in circles because you're treating the *same thing* as two different entities. You cant use one to explain the other.

_- The grind is that way because it's made to have a distal taper above the edge...
- The distal taper is that way because the grind was made to be thinner at the tip...
- The grind is that way because it's made to have a distal taper above the edge... etc


Kippington said:



Here's the thing, both of the following statements are true and sum up the same property:

*The difference between them is in distal taper below the spine:* The top knife has more internal distal taper
*The difference between them is in the grind:* The top knife has a more acute grind towards the tip
So if both statements represent the same thing, the question is: Which description would you prefer to use?

Click to expand...

_


----------



## Kippington

HRC_64 said:


> But it may also be underwhelming from a character or performance perspective.


Well that's the thing. Why would it be underwhelming?
Lets look at the two knives side by side again. The top one has measurements of 1.40mm and 1.00mm consistently across the knife.
The bottom one has a changing grind. Lets say the same measurements (1.40mm and 1.00mm) occur at a certain spot on the blade, three quarters of the way down to the tip. Would that spot on the bottom knife also be underwhelming?

Ignoring cost and manufacturing, I think there are advantages and disadvantages to the performance to both of them, and I would not say the Blazen has a "mediocre grind" in comparison.


----------



## HRC_64

Kippington said:


> I think there are advantages and disadvantages to the performance to both of them....



What are the advantages/disadvantages 
eg of having a no-taper, no variation grind?

this is I guess the general question posed earlier

if one assumes its not inferior, what are the places
and jobs/tasks where it excels?

There's nothing wrong with predictable, cost effective tool,
of course.


----------



## Kippington

HRC_64 said:


> What are the advantages/disadvantages
> eg of having a no-taper, no variation grind?


I'm not sure, are you including spinal taper to this?
No variation grinds have a more consistent feel and are less likely to wedge during push cuts.

______________________

Alright, time to add to the confusion with one of the bonus parts.
*
Distal Taper and it's effect on an Asymmetrical grind*

As many of us already know, there can be advantages to grinding a knife off-centre.




It's a simple enough concept, but what happens when we add distal taper to the mix?

The following triangles represent the spine of a tapered knife, with the middle line going through them representing the cutting edge.




As we know, the cutting edge has to be straight. That's easy enough to do if it runs down the centre of the knife, (a) being an example of that.
Lets look at an asymmetric grind on the knife (b). To maintain a constant ratio of space on the left and right of the edge, we end up with the edge no longer running at the same angle as before.
To have the cutting edge of a tapered knife to run parallel to the handle, the tip of the knife needs to point slightly left or right (c), depending on which bias the knife was designed for.

This is one of the stranger things I've noticed while making tapered knives.


----------



## HRC_64

Kippington said:


> I'm not sure, are you including spinal taper to this?
> No variation grinds have a more consistent feel and are less likely to wedge during push cuts.



Yes, this was the kind of answer I was thinking about. So tapered is sometimes good to use, but then there has to be times (as you mention) it is not ideal.


----------



## Kippington

HRC_64 said:


> Yes, this was the kind of answer I was thinking about. So tapered is sometimes good to use, but then there has to be times (as you mention) it is not ideal.


Yep. That's not taking spinal taper into consideration either, which adds a new element to the mix (details at the end of the first post).
Also, if Uwe considers the Blazen to be a laser it should already be thin behind the edge at the heel. If we had the edge get even _thinner _towards the tip on a laser, it might easily be considered unnecessarily overkill depending on how it's done and who's using it.




If a knife doesn't get thinner towards the tip, it doesn't mean the tip will be fatter behind the edge than it is at the heel.


----------



## Krassi

Hi!

Oh that Takamura Balzen from Suntravel is actually a to big for my taste but its a good laser!
I have tried it often at our Knife gatherings. "oh Suntravel brought his blazen.. Time to destroy some carrots"


----------



## suntravel

Maybe i dont understand your question right Kippington.

But is notice your explanations are all based on dead flat grinds in the sketches, but with some convex and/or hollow grinding it is easy to get different tapers above the edge without touching the taper of the spine 

Regards

Uwe


----------



## Kippington

Yes Uwe, it is also easy to do this with compound grinds. The theory remains the same.


----------



## Kippington

suntravel said:


> ...with some convex and/or hollow grinding it is easy to get different tapers above the edge without touching the taper of the spine



This would be considered by many to be a flat grind, but it still shows different tapers above the edge without touching the taper of the spine:




I'm not sure what your point is.


----------



## suntravel

The point is that there must not be a big correlation between the taper of the spine and the taper above the edge.

Regards

Uwe


----------



## Kippington

You are correct. The taper behind the edge will be determined by (and is also the same thing as) the grind.
Does anywhere in this thread say otherwise?


----------



## Carl Kotte

Thanks @Kippington for the bonus! Though the extra information brings more complexity to the discussion it is also very interesting and rewarding to read. It is much appreciated Santa Attenborough


----------



## Eloh

Kippington said:


> You are correct. The taper behind the edge will be determined by (and is also the same thing as) the grind.
> Does anywhere in this thread say otherwise?



To be fair I don't think he was saying that anyone said otherwise. He was just pointing something out and was trying to expand the definition of distal taper to what you call the grind wich might be a more helpful quantitative perspective in judging "a grind" imo. 



For clarification it might also be helpful to give a simple definition of what you actual mean by distal taper.
Only the spine? 
The thickest part of the blade? (there are actually kitchen knives with more thickness below the spine)
Or the way suntravel uses it? 


 just trying to be helpful here


----------



## Kippington

Carl Kotte said:


> Thanks @Kippington for the bonus! Though the extra information brings more complexity to the discussion it is also very interesting and rewarding to read. It is much appreciated Santa Attenborough



Hey my pleasure!
Here's another one for you:

*Distal taper and the Hamon
*
As most of us know, a hamon can be created during the quench by cooling shallow-hardening steels quickly in certain areas, while at the same time cooling other areas near the spine slowly so they do not harden.
Depending on how accurate we want the hamon placement, distal taper becomes a surprisingly important factor during the quench because the position of the hamon comes from the accuracy of the cooling.
For example, if we quenched a knife which already had a distal taper, the thinner spine in the area closer to the tip would cool faster than the thicker spine near the heel. This leads to less control during the transformation process and the hamon could come out heading up towards the spine earlier than expected.

These two blades were quenched the same way, but the one on the left side had a distal taper during the quench, the one on the right side did not.





The following two are random examples where, with the above knowledge, you can start to piece together whether it was tapered or not before the hardening:







Just remember that a taper can also be ground/grinded in after the heat-treat. The knife above may still be tapered but there's no way for us to know from this picture.


----------



## Carl Kotte

@Kippington You’re too kind! Hope to be able to return the favor at some point. Until then, here’s a dancing chicken! 
Posts like yours is KKF at its best.


----------



## Kippington

Carl Kotte said:


> @Kippington You’re too kind! Hope to be able to return the favor at some point. Until then, here’s a dancing chicken!
> Posts like yours is KKF at its best.


I'll take it!


----------



## Matus

This is an interesting thread, but a bit ‘lost in definition’


----------



## Carl Kotte

Kippington said:


> I'll take it!


I know it’s not much, but it’s the best I can do!


----------



## Kippington

Eloh said:


> To be fair I don't think he was saying that anyone said otherwise. He was just pointing something out and was trying to expand the definition of distal taper to what you call the grind wich might be a more helpful quantitative perspective in judging "a grind" imo.


That was true the first time. He said this on post #48:

_suntravel - So only looking at the distal taper on the spine tells *not* the complete story_
_Kippington - Yes, Uwe is talking about a valid observation..._
We talk about it over the next two pages. Then on post #121:

_suntravel - The point is that there must *not* be a big correlation between the taper of the spine and the taper above the edge._
_Kippington - You are correct._
This is why I need to ask: If Uwe feels the need to repeat himself again after it was already discussed, is it because he feels something in this thread disagrees with his statement? Is he trying to add something else to the discussion, and if so I don't see an explanation from him, other than _"it is *not* this"_ or _"it is *not* that"_.

Uwe, it would be helpful if you tell us what it _*is.*_ That was why this thread was created.


----------



## ian

Eloh said:


> For clarification it might also be helpful to give a simple definition of what you actual mean by distal taper.
> Only the spine?
> The thickest part of the blade? (there are actually kitchen knives with more thickness below the spine)
> Or the way suntravel uses it?



I always like precise definitions, too. I’ve been interpreting “distal taper’’ to just mean “taper as you go toward the tip”, a meta-definition that is clarified by specifying the distance to the spine/edge at which you measure. In most discussions, it’s fine to understand distal taper as being measured on the spine. If you want to get a second level understanding of the grind, you can differentiate between taper at the spine vs taper at some distance above the edge. In Kip’s excellent original post, he mostly talks about the spine. That’s good imo: it makes the discussion simpler, the spinal taper sometimes does predict taper lower down, and some important advantages of a taper really do have to do with spinal taper (eg having a thick spine near the handle for comfort). In general, though, he has been quite precise in his language here.


----------



## suntravel

Kippington said:


> Uwe, it would be helpful if you tell us what it _*is.*_ That was why this thread was created.



I think i have explained what is possible to get an specific distal taper on the spine and above the edge.

If you want to know how to grind it with a large contact wheel or rotary platen let me know, i will try to explain in my broken english 

Regards

Uwe


----------



## McMan

If dancing threads are today's currency of appreciation, here's another for ya, Kippington... 

I would love to see you and Larrin join forces on a website one day...


----------



## Carl Kotte

McMan said:


> If dancing threads are today's currency of appreciation, here's another for ya, Kippington...
> 
> I would love to see you and Larrin join forces on a website one day...


The dancing chicken is really quite good!


----------



## Nikabrik

I think we should also consider historical customary usage. A review of web posts and publications from 1990-2002 indicates that distal taper referred to the thickness portion of the blade, often in relation to tapering before grinding the bevels. It was also used in regard to double-edged swords. In one example, the author started that the distal taper combined with a constant width bevel resulted in bevel geometry that varied continuously over the length of the blade.

I think a tentative working definition could be "lengthwise taper in the thickest contiguous region." Perhaps it would be useful to define spine as the thickest contiguous longitudinal region, rather than the reverse edge, but I'm unsure of that.

I don't mean to imply that changing geometry below the spine is unimportant or unrelated, but I think that creating a separate term/concept, such as "longitudinal grind progression", would be helpful in allowing the discussion of specific concepts. Again, I'm sure that they are intimately intertwined in the design of a knife, but so are lateral grind, profile, material, heat treatment, and handle geometry - thus I am convinced that their separate and distinct discussion is both useful and necessary.


----------



## ojisan

Kippington said:


> Distal taper and the Hamon



I was believing the major factor of the shape of the hamon was the mud that covers the blade. Even with the mud, still does distal taper affect the shape of the hamon so drastically?


----------



## HRC_64

Nikabrik said:


> I think we should also consider historical customary usage. A review of web posts and publications from 1990-2002 indicates that distal taper referred to the thickness portion of the blade, often in relation to tapering before grinding the bevels.



Its maths fact you cannot depict compound curves "accurately" using single-point perspective.

And that "inaccurate" rednerings are fundamentally flawed 

vis-a-vis a technical discussions relating to "geometry"

This isn't something to "celebrate as tradition"


----------



## ian

I think you’re misinterpreting Nikabrik’s post.



Nikabrik said:


> Perhaps it would be useful to define spine as the thickest contiguous longitudinal region, rather than the reverse edge, but I'm unsure of that.



I seem to remember seeing some pictures of weird knives recently where the spine was thinner than the middle of the knife, but I can’t remember the thread. Not sure those examples are prevalent enough to care about, though.

Really nice post! I do like “distal” better than longitudinal. Personally, I think history is wrong and the two terms should be spinal taper and distal grind progression.

Edit: Or actually longitudinal grind progression would be fine too. Longitudinal = along the length of the knife, while distal = going away from the user. So they both make good sense, and mean the same thing. What doesn’t make sense to me is to use one term to mean `along the spine' and the other for something more general about the grind, since they are essentially synonymous. So, either

“spinal taper, distal grind progression”

or

“spinal taper, longitudinal grind progression”.

Take that, history.

2nd edit: Actually, I think just using distal taper as a meta definition, as in my prev post, respects history well enough and works fine.

Probably it’s time for me to stop obsessing about this and let someone else contribute with a post that actually has content...


----------



## Kippington

ojisan said:


> I was believing the major factor of the shape of the hamon was the mud that covers the blade. Even with the mud, still does distal taper affect the shape of the hamon so drastically?


Absolutely. This topic can get technical real quick as it involves things like thermal conductivity, specific heat capacity and dissipation. Here's the simple version:

Heating up steel takes time and energy. Let's say you have two spheres of steel - a small one and a larger one with double the mass. If you take both spheres at room temperature and place them next to each other in an oven set to 800°C, which one will reach the temperature inside the oven first? Naturally the sphere with less mass will reach 800°C first, because the sphere with more mass requires more time and energy to heat up to the same temperature.

Now we wait until both spheres have equalised to 800°C, remove them from the oven at the same time and submerge them into a bucket of water. As you can imagine, the same theory applies to cooling - the smaller sphere cools faster because it contains less heat energy to dissipate.

As you likely already know, the surface of a sphere will cool faster than the center, due to the water only being able to interact with the outside. Cooling the interior of the sphere (where the water cannot reach) relies on thermal conductivity - or in other words: heat travelling through the steel itself.

*How does this apply to a hamon on a knife?*
The clay along the spine will help shield the hot steel from coming into contact with the quenchant. Much like the middle of a sphere, the steel covered by clay loses a lot of its heat through thermal conductivity, with heat travelling towards the cooler steel that _does _touch the quenchant.
The heel of a tapered blade has a thicker cross-section than the tip. This increased mass at the heel holds more heat, which in turn takes a longer amount of time to cool compared to how quickly a thinner cross section at the tip cools. Meanwhile in the thinner areas, heat under the protective blanket of the clay might get pulled out via thermal conductivity fast enough for the steel to harden - even though it's covered by the clay. An alloy's ability to do this is known as the "hardenability" of the steel.





Let's say you're shooting for a hamon in the shape of *(a)* and you apply clay to a tapered blade as such. Then you heat it up and quench it so that the thickness of the heel cools at the perfect speed. Being tapered, the tip cools faster than the heel causing *(b)* to happen, with the heel ending up where you were aiming for but with the tip short of what you wanted _(see pictures a few posts up)_.
So instead you change it up and tailor the quench so that steel closer to the tip cools down at the exact speed you want. Now on a tapered blade you get *(c)*, where the tip turns out perfect but the heel retains its heat during the quench and cools down slower than before (_(b)_), sending the hamon at the heel down towards the edge.
It's a back and forth battle, that's for sure.




I should add, this is what I've noticed during my own quenches. Hey, maybe the knife above was supposed to come out of the quench exactly like this, who knows. Though I'd still put money on it having been tapered before the quench.
_________________________


suntravel said:


> _• ...So only looking at the distal taper on the spine tells not the complete story
> • ...there must not be a big correlation between the taper of the spine and the taper above the edge
> • ...is possible to get an specific distal taper on the spine and above the edge_


Outstanding work Uwe! *Well done!* 
I had almost forgotten about this today. I look forward to hearing about it again tomorrow!


----------



## HRC_64

ian said:


> Really nice post! I do like “distal” better than longitudinal. Personally, I think history is wrong and the two terms should be spinal taper and distal grind progression.



I actually mis-spoke earlier and confused dorsal with distal. The technical definition of distal is from near to far, and refers to the handle to tip not the spine itself. The taper of the spine itself would be 'dorsal' (like the 'dorsal fin' of a shark). 

The key part is if you say a flat-plane (in reference initially to the cutting surfact) is defined as an XY rectangle (width x length) you still need a Z- axis analysis of the tapers as they progress. 

Not sitting in a single plane is important for a couple of reasons, but mostly because product stays still while being cut so the knife moves thru the product in its Z-axis progression (ie along the choil...which is why we place so much emphasis on the 'grind' tapers/cross sectional view).


----------



## HRC_64

The more interesting point from here, however, is "what is the performance of the knife with the Z-axis tilted to be tangential with the edge-profile"

For example, lets use a simplified knife witha flat handle angle (perfectly parallell to the cutting surface) and a perfect "dead flat" back 1/3rd of the blade.

At some stage this knife is going to have the forward 1/3rd cutting edge raise to meet the tip, and there is often a "forward sweet spot" where the knife can be used at this transition area. In order to make clean cuts on teh forward sweet spot, the tip is pointed down and the handle is raised such that now the food is being cut approximately (note:approximately) tangential to the curve of the profile in the forward upsweep.

This angle of attack of the blade means that the correct Z-axis progession involves not the spien directly over the froward sweet spot, but rather back (proximal) closer to the hand. So the proximal to distal profession of the spine (ie "distal taper") comes into play here in how the knive performs...because the grind will be more or less "wedgy" (think food release) depending on the taper progession and this "angle of attack" vis a vis the product.

Also push/pull implicates differnt interaction with the spine (uppermost Z-axis) tapers.

This kind of how the grind on masamoto KS works, IMHO. Ther can be a noticeble difference moving along the edge as it upsweeps, and a noticible/constrasting reversal when swiching push/pull motions that is sometime quite dramatic.


----------



## M1k3

McMan said:


> I would love to see you and Larrin join forces on a website one day...


----------



## ojisan

Kippington said:


> Absolutely. This topic can get technical real quick as it involves things like thermal conductivity, specific heat capacity and dissipation. Here's the simple version:
> 
> Heating up steel takes time and energy. Let's say you have two spheres of steel - a smaller one and a larger one with double the mass. If you take both spheres at room temperature and place them next to each other in an oven set to 800°C, which one will reach the temperature inside the oven first? Naturally the sphere with less mass will reach 800°C first, because the sphere with more mass requires more time and energy to heat up to the same temperature.
> 
> Now we wait until both spheres have equalised to 800°C, we remove them at the same time and submerge them into a bucket of water. As you can imagine, the same theory applies to cooling - the smaller sphere cools faster because it contains less heat energy to dissipate.
> 
> As you likely already know, the surface of a sphere will cool faster than the middle, due to the water only being able to interact with the outside. Cooling the interior of the sphere (where the water cannot reach) relies on thermal conductivity - or in other words: heat travelling through the steel itself.
> 
> *How does this apply to a hamon on a knife?*
> The clay along the spine will help shield the hot steel from coming into contact with the quenchant. Much like the middle of a sphere, the steel covered by clay loses a lot of its heat through thermal conductivity, with heat travelling towards the cooler steel that _does _touch the quenchant.
> The heel of a tapered blade has a thicker cross-section than the tip. This increased mass at the heel holds more heat, which in turn takes a longer amount of time to cool compared to how quickly a thinner cross section at the tip cools. Meanwhile in the thinner areas, heat under the protective blanket of the clay might get pulled out via thermal conductivity fast enough for the steel to harden - even though it's covered by the clay. An alloy's ability to do this is known as the "hardenability" of the steel.
> 
> 
> 
> 
> 
> Let's say you're shooting for a hamon in the shape of *(a)* and you apply clay to a tapered blade as such. Then you heat it up and quench it so that the thickness of the heel cools at the perfect speed. Being tapered, the tip cools faster than the heel causing *(b)* to happen, with the heel ending up where you were aiming for but with the tip short of what you wanted _(see pictures a few posts up)_.
> So instead you change it up and tailor the quench so that steel closer to the tip cools down at the exact speed you want. Now on a tapered blade you get *(c)*, where the tip turns out perfect but the heel retains its heat during the quench and cools down slower than before (_(b)_), sending the hamon at the heel down towards the edge.
> It's a back and forth battle, that's for sure.
> 
> 
> 
> 
> I should add, this is what I've noticed during my own quenches. Hey, maybe the knife above was supposed to come out of the quench exactly like this, who knows. Though I'd still put money on it having been tapered before the quench.
> _________________________
> 
> Outstanding work Uwe! *Well done!*
> I had almost forgotten about this today. I look forward to hearing about it again tomorrow!




Thanks!
I was sure that distal taper definitely affects to some extent but I was wondering how much was that as I didn't hear distal taper affects honyaki hamon before.

I now assume this is probably single beveled knives are tend to be thicker and their distal taper is not so steep, or even no taper at quenting as @Kippington suggested, meaning less affected by the taper. 

Another possibility is that they change the position and/or thickness of cray to cancel the affect by the taper.

I'm attaching how Ikeda Tatsuo-san put cray on his yanagiba to show what we are talking about. This is from a TV show by TV Asahi in 2013, which was very interesting.


----------



## Kippington

Matus said:


> This is an interesting thread, but a bit ‘lost in definition’


That's because the words leave little in the way of deviation. Much like talking about the_ 'circumference'_ of a circle, the idea of this thread was to understand how it ties into the things connected to it, not to explain what it is.

*distal*
_ - situated away from the centre of the body or from the point of attachment_
*taper*
_ - diminish or reduce in thickness towards one end_​
Lets check out a picture of a knife profile.



Clearly the blade has an attachment to the handle. The blade also has a tip, which is the most distal extent of the blade from the point of attachment. It would be incorrect to say that the blade *profile *is distally tapered - The choil increases in thickness from point of attachment (at the handle) till it reaches the heel, and only then does it taper towards the tip.
So we can say: To have true distal taper, an object needs to diminish in thickness the whole distance - from the point of attachment all the way to the tip. The profile of this knife doesn't have it, but the thickness of the spine might, and that is generally what we're talking about.



Looking down on the spine from above (or looking up at the edge from below), we can see the thickest cross section of steel at any height down the distal length of the blade. This is important because in the world of blades, the spine doesn't necessarily run along the top length of the steel, meaning it can't always be described as a 'dorsal' taper.




_________________

Lets do what Uwe did and measure the thickness of the knife at a certain height above the edge, as shown by this red line.



As mentioned earlier, I prefer to think of the red line as a measurement of the grind, rather than distal taper. There are three reasons for this:

The red line never intersects with the neck area, where the blade attaches to the handle. It also cannot ever intersect with the tip of the knife: the most distant point from the handle (unless the height measured above the edge is zero). With both ends of the red line in question, I would argue that this measurement cannot truly be described as 'distal', and might be better described as 'adjacent to the edge'.

The red line is limited to only showing taper within the confines of the grind. At best this could be called a taper of the grind towards the tip, and not a distal taper in reference to the entire blade. Viewing from the spine gives a more accurate idea of the overall thickness down the entire distal length of the blade.

If we were to make an accurate description of the grind, it would require utilising the cutting edge as a point of reference. The same is true for the red line - It doubles up on the same information as the grind, while at the same time not actually representing a true 'distal' measurement.
I believe that in the blade-world lexicon, 'distal taper' refers specifically to the spine. I should've added this to the original post to help clarify things, but it might've been confusing and it's too late to edit the post now anyway.
I was also careful in my wording to allow for other interpretations as well. All of what I've said works for distal taper outside of the spine too... just not along the knife profile, as I explained at the start of this post.


----------



## suntravel

In the german forums, we call it distal taper of the spine and distal taper above the egde 

Regards

Uwe


----------



## RDalman

Guys, it's not about the distal taper, it's about the girth really.


----------



## Carl Kotte

suntravel said:


> In the german forums, we call it distal taper of the spine and distal taper above the egde
> 
> Regards
> 
> Uwe



Yes, and now we all know that we don’t need to do so on this forum unless we want to stir up unnecessary confusion and make it appear as if there’s genuine disagreement where there is only verbal disagreement. [emoji1303] That’s great!


----------



## Luftmensch

This is a strangely passionate thread!



ian said:


> I appreciate references to geometry, being a mathematician whose research area is geometric topology.... It was interesting to note that people in the nautical world also care about distal taper, but maybe let’s leave the conversation at that...



A mathematician on the forum. That is pretty cool! Nice!

Credit to @HRC_64: generating a transition between profiles in CAD is referred to as lofting - named after the drafting technique used in the design of ships and aircraft. Beyond that... references to non-portable nautical terminology doesnt add to the conversation.



Kippington said:


> You're saying the Blazen's spine gets thinner towards the tip, yet the grind remains completely unaffected by this? This makes no sense to me.
> If the spine gets thinner down it's length. the primary bevel will have to get smaller too - either by height or by angle. By my reckoning, this would be called a tapered grind.



@Kippington: after consideration, do you still stand by this? Perhaps you mean specifically for the Blazen rather than the general case?

In the general case I dont see why the spine _*cant*_ get thinner towards the tip while keeping a constant grind? Imagine a triangle for a primary bevel grind (point down). It is 10mm tall and 1mm wide at the top. Sweep this along the profile of the cutting edge. This ensures the primary bevel is the same height and angle across the length of the knife. At this stage the 'knife' is only the primary bevel and it is 1mm at its thickest. Why not fill in the rest of the volume how you please? For example; such that the thickness of the spine at the heel is thicker than 1mm? The surface will curve in multiple dimensions, it might not be easy/practical to manufacture , but it is not an impossible construct.



Kippington said:


> As mentioned earlier, I prefer to think of the red line as a measurement of the grind, rather than distal taper.



Hehe... I guess it depends on what 'grind' means. I just think of the red (shinogi) line as where the blade road (primary bevel) ends and the 'flat' or face begins. It is neither grind nor distal taper. It is simply a nexus between two geometries - as such it is affected by altering the primary bevel or face. I suppose... to that end... the red line is a measurement of _both_ grind and blade face. 

Not that this helps the discussion


----------



## ian

Luftmensch said:


> I just think of the red (shinogi) line as where the blade road (primary bevel) ends and the 'flat' or face begins. It is neither grind nor distal taper. It is simply a nexus between two geometries - as such it is affected by altering the primary bevel or face. I suppose... to that end... the red line is a measurement of _both_ grind and blade face.



FWIW, I think the red line in the picture is just supposed to be where Uwe is taking his measurements, i.e. a distance of 1cm or something above the edge. It's not a shinogi line or anything, it's just indicating the curve along which one is assessing the grind.


----------



## Kippington

ian said:


> FWIW, I think the red line in the picture is just supposed to be where Uwe is taking his measurements, i.e. a distance of 1cm or something above the edge. It's not a shinogi line or anything, it's just indicating the curve along which one is assessing the grind.


Yep, this is correct.


Luftmensch said:


> @Kippington
> In the general case I dont see why the spine _*cant*_ get thinner towards the tip while keeping a constant grind? Imagine a triangle for a primary bevel grind (point down). It is 10mm tall and 1mm wide at the top. Sweep this along the profile of the cutting edge. This ensures the primary bevel is the same height and angle across the length of the knife. At this stage the 'knife' is only the primary bevel and it is 1mm at its thickest. Why not fill in the rest of the volume how you please? For example; such that the thickness of the spine at the heel is thicker than 1mm? The surface will curve in multiple dimensions, it might not be easy/practical to manufacture , but it is not an impossible construct.


The problem with this is that you're defining the grind as something that ends at a certain height above the edge.


suntravel said:


> The grind is where a blade is grindend


Even though 10mm close to the edge is very important, other stuff _still _needs to happen above this height on both faces, closer to the spine. On most knives this would still be classified as the grind. I guess calling it the 'face' would be more accurate in cases where some of the sides are forge-finished, but on specific examples like the Blazen, the 'grind' goes all the way up to the spine from the edge.

Let me put it another way. Lets say you had a completely flat-ground knife with a triangle cross-section - all three sides with straight edges - and it just so happens that the triangle you quoted above (10 x 1mm) fits exactly into the bottom of this cross-section. Does this mean that the grind ends at the 10mm tall mark, even though the sides are flat all the way up to the spine?



It doesn't make any sense to me.


----------



## suntravel

Distal is a wording from the anatomy, that means away from the center.

If you define the point where the blade goes in to the handle is the center, every definded line on the blade thats have a taper to the tip has a distal taper.

Could be the spine or any distance above the egde, or the thickest part of te blade, thats not allways the spine, depends on the grind.

I think taking the measurements on the same distance (s) above the edge give some clue how the blade cuts.

But no problem then distal taper is here only used for the spine as a simple definition 

Regards

Uwe


----------



## HRC_64

Agree. The red line is a line that goes from handle to tip travels from "proximal" to "distal" and therefore the taper that occurs along its length....is indeed a "distal taper."


----------



## Carl Kotte

HRC_64 said:


> Agree. The red line is a line that goes from handle to tip travels from "proximal" to "distal" and therefore the taper that occurs along its length....is indeed a "distal taper."



Please just look up the meaning of ’explicative’ and ’stipulative’ definitions and let this be!


----------



## Kippington

Even a red line that starts at the heel instead of the proximal connection? One that, by definition, has to curve away from the tip?
That's cool by me. I'll still call it "adjacent to the edge".


----------



## HRC_64

A curve ("along the profile") from heel to tip is a distal taper...whether or not it curves, etc...because its a line and lines can curve.

The issue with curved lines being used when talking about taper is different in relation to the spine vs the edge...

The spine taper isn't neither in the same plane nor equidistant from the edge, so its an aribatrary sort of thing...other than it contains information as the maximal value of grind width (typically although not always, etc).

So now we have 3 different ideas of "THE" distal taper:

1) in reference to the maximal value (eg, the spine)
2) in reference to a plane (and set of planes) in 3D space
3) in reference to the minimal value (eg, above the edge)

This trace of the edge is actaully a cumulation of points orthogonal to the tangent of the profile...ie, the idea discussed earlier as being relevant to the discussion of tapers...since the profile typically makes contact with the cutting surface at a tangent to the profile...the profile thickness above the edge on a line tangent to the profile is of particular functional interest in describing knife performance.

Which brings us back to the interaction of the profile and the angle of attack of the grind. And the trace of how the grind tapers from choil to tip...ie the set of distal tapers

This is why reference about "the grind" and "distal taper" as completley different ideas is a fundamental mis-inderstanding. Perhaps this is a problems that stems from using a single concept "THE" grind and "THE" taper...

IMHO...but I prefer tapers in reference to planes, because knowing its an (arbitrary) reference plane reminds us that there is a SET of planes and the COMPLETE SET of the tapers is actually the more accurate geometrical description of a 3D object.

This is probably because I learned 3D drawing from engineering perspective. 

For a knife maker they don't need to undestand the design, other than they need to understand how it "feels" in use and make sure it works correctly. In other fields like aeronautics and natical, etc...the arhitencts and designers are different people than the builders...so the ideas need to be documented and communcated more preciseley.


----------



## Kippington

HRC_64 said:


> This is why reference about "the grind" and "distal taper" as completley different ideas is a fundamental mis-inderstanding.


I believe there was only one person that said that. It's been mentioned numerous times that they overlap in definition.

You keep saying "to the tip", do you mean "towards the tip"? The red line does one, not the other.
It sounds like a complete set of tapers would describe essentially the whole knife. I'll leave that thread for someone else to write.


----------



## HRC_64

Kippington said:


> It sounds like a complete set of tapers would describe essentially the whole knife.



This thread was originally labeled as "understanding distal taper"... not "incomplete understanding of distal taper"...so the whole set is relevant.


----------



## HRC_64

Kippington said:


> You keep saying "to the tip", do you mean "towards the tip"? The red line does one, not the other.



I'm not sure this matters in any way, 'to' and 'toward' are interchangible in this context.


> adverb. toward a point, person, place, or thing, implied or understood. toward a contact point or closed position



'...toward a contact point or closed position'


----------



## ModRQC

I surely won't argue "scientifically" against anyone here (  ), or regarding anything about knives... but the battle that rages is on terminology, not on concepts and their understanding, as have already been pointed out on a couple of occasions.

I do think that because the terminology isn't set in stone, it is interesting that all contributors here at one point or another have "defied" or "stratified" the way Kippington uses it, because it truly may help to shed some light - certainly not on what you people say and understand in the same way to some extent, but on how to say it. 

I guess that forming a consensus on terminology would take a great deal of time and arguing, but in the meanwhile it's kind of sad because a lot of precious information is being lost in transition for less knowledgeable readers. I was able to reckon when an argument was more about terminology but at times I felt like a good point was also lost in useless debating.

What I could suggest - take it as you may - is that when, on a thread meant to be a guide or some other form of informational hand down, an terminology/pov argument gets in the way, it could simply be transposed into a new thread, and until settled, the original thread remain unaffected. If ever the OFC is proved wrong, then its his responsibility to modify his post; and whenever a debate occurs, the OFC could also point out towards it for interested readers.

If the argument however is conceptual, it should remain within the original thread.

Or something... just ignore me if I sound stupid.


----------



## Eloh

You're overthinking this, it's no about defining what the grind is. In judging a knife these "red lines" (call them what you want) let's say one right above the edge, one at 10mm, one at 20mm help tremendously in judging what a knifes performance will be like, hence a lot of people use them (outside of this forum). Of course they dont tell you everything either but they are helpful


----------



## Carl Kotte

Ok, so it seems that yet another interesting thread with great content has been hijacked.
Here is a thought (in fact a condensed version of something in the spirit, I take it, of what @ModRQC said above): it is very likely that 'distal taper' has a technical (yet perhaps vague and in some respects unclear) meaning in the discussion of kitchen knives. Now OP clearly states in what sense 'distal taper' is going to be used in the posts. Some think that this sense does not correspond to how the term is actually used, and not everyone agrees that the term should be used that way; but so what? I'm not sure who is right (and I'm not sure there is one settled ordinary sense here), but even if there is one, clearly, it most be allowed to use a term to describe one specific phenomenon pertaining to some properties of the knife. We got a great post treating a particular aspect of blade geometry. If someone thinks that one cannot state anything interesting about a particular aspect of blade geometry without accounting for all facts relevant for a good geometry (what about stickage, what about thinness behind the age, what about heft, what the hell - why not include discussion of the steel, the handle, the person holding the knife as well, etc etc), I personally disagree. Focus on particular aspects are interesting: and they do in no way contradict the importance of other aspects. 
At any rate, it would be sad if some of the great content of this thread were lost because a dogmatic fight over labelling.


----------



## ian

Carl Kotte said:


> Ok, so it seems that yet another interesting thread with great content has been hijacked.
> Here is a thought (in fact a condensed version of something in the spirit, I take it, of what @ModRQC said above): it is very likely that 'distal taper' has a technical (yet perhaps vague and in some respects unclear) meaning in the discussion of kitchen knives. Now OP clearly states in what sense 'distal taper' is going to be used in the posts. Some think that this sense does not correspond to how the term is actually used, and not everyone agrees that the term should be used that way; but so what? I'm not sure who is right (and I'm not sure there is one settled ordinary sense here), but even if there is one, clearly, it most be allowed to use a term to describe one specific phenomenon pertaining to some properties of the knife. We got a great post treating a particular aspect of blade geometry. If someone thinks that one cannot state anything interesting about a particular aspect of blade geometry without accounting for all facts relevant for a good geometry (what about stickage, what about thinness behind the age, what about heft, what the hell - why not include discussion of the steel, the handle, the person holding the knife as well, etc etc), I personally disagree. Focus on particular aspects are interesting: and they do in no way contradict the importance of other aspects.
> At any rate, it would be sad if some of the great content of this thread were lost because a dogmatic fight over labelling.



+1

In general, though, I don’t mind discussions about definitions. It’s interesting to me to talk about how best to balance the history, accuracy and utility of a term, and an accurate definition of a concept often improves one’s understanding of it.

What’s problematic here is that there have been like 50 posts about it, with about 2 paragraphs total of new content.

Edit: and now here I am contributing further to the problem. *sigh*


----------



## Carl Kotte

ian said:


> +1
> 
> 
> Edit: and now here I am contributing further to the problem. *sigh*



You can always delete everything except the +1!


----------



## Luftmensch

ian said:


> FWIW, I think the red line in the picture is just supposed to be where Uwe is taking his measurements, i.e. a distance of 1cm or something above the edge. It's not a shinogi line or anything, it's just indicating the curve along which one is assessing the grind.



Doh! I 100% agree


----------



## HRC_64

ModRQC said:


> If the argument however is conceptual, it should remain within the original thread.



The core argument is about geometry, which is fundamentally conceptual.

1) You either describe a shape "accurately" (which means completely) or you caveat your description as being "incomplete".
2) If you are using an "incomplete" description of geometry, and someone points out the "incomplete" description, don't argue about it.
3) Engage in a legitamate discussion about the pro and con's of different approaches to the problem (eg completeness).

Completeness is important for obvious reasons, but it also has some limitations which should be respected.

In a theoretical discussion ("Understanding X") its imporant to talk about completeness, so that if its deemed better to truncate the discussion (eg, for clarity, easy of use, etc) you properly understand what you are leaving out.


----------



## ian

Pro-tip: calling something X makes it theoretical. The _most_ theoretical material, to mathematicians at least, is usually denoted with 3 adjacent X’s.


----------



## Krassi

Hi well grinding is no a theoretical but a very practical thing that cant be allways described with norms.
I have tried so many knifes of suntravel and i would call him one of the best grinders with a feeling for is that you just do and it works.
The best cutting knifes i had are from him and he is a darth vader in pimping crap geometries of the best knifes around.
Really i had a lot of knifes in the hand since i also make the biggest private kitchen knive gathering in germany.. so 

When it works its not stupid and like with many shokunins and craftsman you do it .
Sorry for my monolog but you cantd grind a knife with theory only 

best regards Daniel


----------



## HRC_64

ian said:


> Pro-tip: calling something X ...



Is also a literary device ...


----------



## ian

Krassi said:


> Hi well grinding is no a theoretical but a very practical thing that cant be allways described with norms.
> I have tried so many knifes of suntravel and i would call him one of the best grinders with a feeling for is that you just do and it works.
> The best cutting knifes i had are from him and he is a darth vader in pimping crap geometries of the best knifes around.
> Really i had a lot of knifes in the hand since i also make the biggest private kitchen knive gathering in germany.. so
> 
> When it works its not stupid and like with many shokunins and craftsman you do it .
> Sorry for my monolog but you cantd grind a knife with theory only
> 
> best regards Daniel



One expects, though, that all craftsman (Uwe included, from his posts above) have some idea of what they want to accomplish with a grind. That’s theory, no? And theory is why we read these threads... it wouldn’t be as effective if Kippington had started the thread with “now, you sort of grind more towards the tip of the knife till it feels right, then you try to cut something, and it’s awesome, because you’re me!”


----------



## The Edge

This thread has turned into a spanish soap opera. Kip could have probably named the thread better with, "Distal Taper of the Spine," since that's what this was about, and not a complete description of geometry. Ego's should get checked at the door, and instead of arguing about semantics, we should just get on with our lives. 

I love how two people, who have jumped all over him, have since made mistakes with words, and try to argue that it doesn't matter when they make the mistake. And, neither have ponied up to write about the subject themselves. Start a new thread, or spare us the drama. 

I appreciate the time and effort you've taken to try and impart some of your knowledge Kippington. Haters gonna hate, keep being you, and don't let them steal your swagger.


----------



## Kippington

HRC_64 said:


> In a theoretical discussion ("Understanding X") its imporant to talk about completeness, so that if its deemed better to truncate the discussion (eg, for clarity, easy of use, etc) you properly understand what you are leaving out.


Well in that case, no explanation of anything has ever been (or ever will be) complete. That doesn't make me feel so bad.


----------



## Marek07

Kippington said:


>


One of my very favourite quotes!


----------



## Luftmensch

Kippington said:


> The problem with this is that you're defining the grind as something that ends at a certain height above the edge.





Kippington said:


> Even though 10mm close to the edge is very important, other stuff _still _needs to happen above this height on both faces, closer to the spine. On most knives this would still be classified as the grind.



In my mind, it has made more sense to define the 'grind' as the cross-sectional profile of the primary bevel ending at the Shinogi line. On convex grinds this 'line' is where the primary bevel reaches the blade faces at a tangent (ie invisibly).

It has not been my instinct to include the blade faces as part of the 'grind' but I have no objection doing so!


----------



## ian

HRC_64 said:


> its imporant to talk about completeness



Also, you missed a 't'. 


Edit: sorry, I need to get a life... I think the basic point here, though, @HRC_64, is that noone disagrees with you that it’s good to look at the whole picture and indicate what your simplifications are. Rather, it’s just that we’ve already talked about this like 10 times.


----------



## labor of love

“Why yes, I’d like 2 tickets to pedantic town please.”

“Here you go sir, enjoy your trip.”


----------



## Kippington

HRC_64 said:


> 'to' and 'toward' are interchangible in this context.


This doesn't sound right to me. It's like saying:
_"Walk *to* the sun" instead of "Walk *toward *the sun"._
Are you saying these mean the same thing? Sounds like an important distinction to me.

I know I'm adding to the silliness of this thread... but hey, it's mine


----------



## Luftmensch

Kippington said:


> Does this mean that the grind ends at the 10mm tall mark, even though the sides are flat all the way up to the spine?



Of course not... Not for that choice of geometry. But that wasn't what I described.

I'm happy to include up to the spine in a definition of 'grind'. It just changes the way I think of 'grind' and means that distal taper is a function of grind

... I'm just thinking out loud!


----------



## Kippington

I was just answering your post where I think you misunderstood what the line represented.


----------



## Luftmensch

labor of love said:


> “Why yes, I’d like 2 tickets to pedantic town please.”



Just to be clear... Two full fares


----------



## Kippington

labor of love said:


> “Why yes, I’d like 2 tickets to pedantic town please.”
> 
> “Here you go sir, enjoy your trip.”


It's a good time to mention, this is why I don't think I'll ever start a similar thread on grinds - the topic is more detailed and opinionated than the others I've done (asymmetry, taper and profiles), which all but guarantees this kind of off-topic pedantic derailment happening again. It isn't worth taking the time to write.

Sorry @M1k3!


----------



## ian

Do it and lock the thread? I’ll start the Kickstarter.


----------



## dafox

Kippington said:


> It's a good time to mention, this is why I don't think I'll ever start a similar thread on grinds - the topic is more detailed and opinionated than the others I've done (asymmetry, taper and profiles), which all but guarantees this kind of off-topic pedantic derailment happening again. It isn't worth taking the time to write.
> 
> Sorry @M1k3!


That's too bad, thank you for what you did share. I would like to learn more.


----------



## Nikabrik

I, too, have learned a lot from reading your posts @Kippington. I appreciate your generosity in sharing that you have. I think your work speaks for itself in your grasp of knife performance. 
Grinds are an area I'd love to learn more about, and I especially admire your work in that area. I'd absolutely read that thread, but I know you've gotta do what's right for you.


----------



## M1k3

Kippington said:


> It's a good time to mention, this is why I don't think I'll ever start a similar thread on grinds - the topic is more detailed and opinionated than the others I've done (asymmetry, taper and profiles), which all but guarantees this kind of off-topic pedantic derailment happening again. It isn't worth taking the time to write.
> 
> Sorry @M1k3!



PM it to me. I'll buy four full price tickets to pedantic town.


----------



## ian

Going the wrong direction, unfortunately... although as long as you’re only going _toward _pedantic town, as opposed to all the way there, you’ll be fine.


----------



## McMan

dafox said:


> That's too bad, thank you for what you did share. I would like to learn more.





Nikabrik said:


> I, too, have learned a lot from reading your posts @Kippington. I appreciate your generosity in sharing that you have. I think your work speaks for itself in your grasp of knife performance.
> Grinds are an area I'd love to learn more about, and I especially admire your work in that area. I'd absolutely read that thread, but I know you've gotta do what's right for you.


Me too. For sure.
Kick your feet up and have a beer. It was a thoughtful post. Not your fault that the record started skipping. Please don’t let that dissuade you from putting together more posts about grind.
You're generous with your knowledge and your work shows how systematically you've thought about process and production. Keep on keepin on!



ian said:


> Do it and lock the thread? I’ll start the Kickstarter.


Seriously. Throw an asterisk on it—"debates about ontology and the philosophy of language are outside the scope of this post."


----------



## labor of love

M1k3 said:


> PM it to me. I'll buy four full price tickets to pedantic PARADISE.


----------



## Carl Kotte

@ian You seem like a very sensible person with quirky interests: if you want to define some terms sometimes shoot me a pm. I also appreciate conceptual analysis. This might not be the best place for that kind of discussion though.


----------



## Kippington

ian said:


> Going the wrong direction, unfortunately... although as long as you’re only going _toward _pedantic town, as opposed to all the way there, you’ll be fine.


Haha YES!!!


----------



## ian

So, here's an actual question.

What are the benefits of linear/convex/concave tapers? I'm guessing that if you want a consistent feel throughout most of the grind, you may want something `concave', where you narrow down pretty fast from the thick spine at the handle, and then stay at the same thickness(ish). On the other hand, a linear taper would also be `consistent' in a sense throughout the entire blade. A convex example would be a knife with not much taper in most of the blade, but a thin tip, perhaps with a blending of the two `taper bevels'. Are there examples where it's advantageous to have a more gradual convex to the taper? Do you think I'll ever feel an advantage in food release or stiction from the curvature of the distal taper? It can certainly increase the (2-d) curvature of the blade face, thus making it harder for food to stick, but it seems like it would have to be so gradual that it wouldn't matter. Also, maybe it's just too hard to grind a distal taper with this level of control. Curious to know what others think, or if I'm just obsessing over something trivial that hardly makes a significant difference in performance. I've never ever been known to do that, AFAIK, but....


----------



## Luftmensch

Kippington said:


> I was just answering your post where I think you misunderstood what the line represented.



100% agree with you. I took it to be a shinogi line. It is just some arbitrary distance from the blade edge... But lets not take that any further.

I am genuinely trying to understand this though:



Kippington said:


> If the spine gets thinner down it's length. the primary bevel will have to get smaller too - either by height or by angle. By my reckoning, this would be called a tapered grind.



In the general case, the height and angle of the primary angle can be held constant for a tapering spine. Sure, the grind changes across the length of the blade but in the previous thought experiment I raised (distinctly different from a flat-ground knife), the spine is free to get thinner down it's length and the primary bevel remains constant.


----------



## Kippington

Kippington said:


> If the spine gets thinner down it's length. the primary bevel will have to get smaller too - either by height or by angle. By my reckoning, this would be called a tapered grind.


This is what I mean:



The two heel cross sections are the same. If you shrink the spine in width, some aspect of the grind will have to shrink as well. It can either change in height or change in angle, that or a combination of the two.

A real-world example of this is the Kato WH Gyuto. Here's a small snippet from the terrific review in *this thread*:

_"The knife is quite thick. At the heel it is 5 mm wide at the spine and halfway the blade it is still 2.8 mm wide. This tapers down to 1 mm at 1 cm from the tip. At 250 grams it is the heaviest knife in my collection."_



_"...In the picture below the red line indicates where approximately the main convexity curve is. The blade does not have a shinogi line, but if it were to have one, this would about be where it is."_​





Luftmensch said:


> In the general case, the height and angle of the primary angle can be held constant for a tapering spine. ...the spine is free to get thinner down it's length and the primary bevel remains constant.


I'm not sure how you're saying the bevel can remain constant. I'd love to know what you mean.

_Note: I am only posting diagrams of flat grinds for the sake of simplicity. I feel this general principle applies to other grinds as well._


----------



## ojisan

Kippington said:


> This is what I mean:
> 
> 
> 
> The two heel cross sections are the same. If you shrink the spine width, some aspect of the grind will have to shrink as well. It will either change in height or change in angle. With other grinds it can be a combination of the two.
> 
> I'm not sure how you're saying the bevel can remain constant. I'd love to know what you mean.
> 
> _Note: I am only posting pictures of flat grinds for the sake of simplicity. I feel this applies to other grinds as well._



This picture is really helpful when I explain the fact that you cannot sharpen an usuba all along with a single angle (and the tip of a deba is fragile than it appears if the bevel width is same at the tip and heel). Thanks!


----------



## Kozuka

To be fair and ask an important question form a customer point of view, how do I explain to a maker what I mean if I tell him I want a distal taper for my custom knife? Honestly if I tell it to a maker and we both agree on a strong distal taper I take it for granded we are talking about the whole knife and not only the spine. So yes the "close to bevel" part also should have a strong distal taper if I order a knife this way. Maybe I'm wrong in assuming this by default. Please enlighten me.


----------



## Kippington

Kozuka said:


> Honestly if I tell it to a maker and we both agree on a strong distal taper I take it for granded we are talking about the whole knife and not only the spine. So yes the "close to bevel" part also should have a strong distal taper if I order a knife this way. Maybe I'm wrong in assuming this by default. Please enlighten me.


Good question. I would definitely not assume it one way or the other. Any good knife maker should be able to do both, but unless you already know what they prefer to do, it's not easy to tell which one you're going to get.
It's best to specify these details early on. Something like "I'd like a grind that gets more acute towards the tip, as well as spinal distal taper" makes sense to me.


----------



## Luftmensch

Kippington said:


> The two heel cross sections are the same. If you shrink the spine width, some aspect of the grind will have to shrink as well. It will either change in height or change in angle. With other grinds it can be a combination of the two.



True... but dont constrain yourself to orthogonal planes. I agree with you 100%. Something about the grind has to change!



Luftmensch said:


> Sure, the grind changes across the length of the blade



What if we introduce a twist to the face of the blade? This is where lofting (and loosely boat building ) comes in. We can sweep from one profile to another along a curve - we can choose to keep the primary bevel constant. I suppose this is why I was quick to conceptually separate the primary bevel from the face of the blade. The face of the blade will have a complex geometry with curvature in multiple dimensions whereas the primary bevel will be relatively simple. Again:



Luftmensch said:


> The surface will curve in multiple dimensions, it might not be easy/practical to manufacture , but it is not an impossible construct.



Perhaps only a CNC machine could achieve this grind? I am not saying anything other than it is a possible/valid volume. It may cut terribly! It may be expensive as hell... It may offer zero benefits! 



Kippington said:


> I'm not sure how you're saying the bevel can remain constant. I'd love to know what you mean.



We can keep a constant primary bevel (cutting angle and height) by sweeping that profile down the length of the cutting edge. 

You are being patient and generous with me. Thank you! To reciprocate in some small way, I'll fire up the CAD etc and try to render a clean example - but there is one catch. You have to allow me some time? Maybe at least until the weekend. Maybe sooner. Im not sure when I'll be able to squeeze it in?

How does that sound?



(Oh... and I think I am sweeping one thing under the rug. I can only think about how to draft this so the primary bevel is a constant in the plane at a tangent normal to the edge. _Not_ an orthogonal XYZ plane)


----------



## Kippington

Awesome! If you can spare the time I'd love to see what you come up with.
I have no doubt in my mind that it would be possible with some crazy impractical curves and twists above the shinogi.

There are definitely some things to consider: If the knife ever gets thinner at the spine than the thickness of the sweeping 'triangle grind' you mentioned, it would create a cross-section near the tip in which the thickest part is at the shinogi. In turn, this would make the shinogi the new 'real-spine'.
And if you decide against allowing this to happen, the thinnest part of the spine (before reaching the grind) would have to be the same thickness as your triangle, ruling out the possibility of a taper that looks like this:




You also run the risk of the cross-section at the heel looking like a flat-top mushroom with a sharpened stem!


----------



## Dhoff

My brain imploded reading this thread.
Thank you for an interesting read, especailly the last couple of posts are extremely relevant to me knowing how to specify distal taper to a maker!
Thanks Kip.

EDIT:
Next thing is understanding how different grinds and tapers affect the knifes performance...


----------



## HRC_64

Kippington said:


> This doesn't sound right to me. ...



You've already been presented with the dictionary...I suggest you actually read it. 




ian said:


> Edit: sorry, I need to get a life...



I'm impressed that the first mark you missed you went back to look for another try...


----------



## ian

Luftmensch said:


> True... but dont constrain yourself to orthogonal planes. I agree with you 100%. Something about the grind has to change!
> 
> 
> 
> What if we introduce a twist to the face of the blade? This is where lofting (and loosely boat building ) comes in. We can sweep from one profile to another along a curve - we can choose to keep the primary bevel constant. I suppose this is why I was quick to conceptually separate the primary bevel from the face of the blade. The face of the blade will have a complex geometry with curvature in multiple dimensions whereas the primary bevel will be relatively simple. Again:
> 
> 
> 
> Perhaps only a CNC machine could achieve this grind? I am not saying anything other than it is a possible/valid volume. It may cut terribly! It may be expensive as hell... It may offer zero benefits!
> 
> 
> 
> We can keep a constant primary bevel (cutting angle and height) by sweeping that profile down the length of the cutting edge.
> 
> You are being patient and generous with me. Thank you! To reciprocate in some small way, I'll fire up the CAD etc and try to render a clean example - but there is one catch. You have to allow me some time? Maybe at least until the weekend. Maybe sooner. Im not sure when I'll be able to squeeze it in?
> 
> How does that sound?
> 
> 
> 
> (Oh... and I think I am sweeping one thing under the rug. I can only think about how to draft this so the primary bevel is a constant in the plane at a tangent normal to the edge. _Not_ an orthogonal XYZ plane)





Kippington said:


> Awesome! If you can spare the time I'd love to see what you come up with.
> I have no doubt in my mind that it would be possible with some crazy impractical curves and twists above the shinogi.
> 
> There are definitely some things to consider: If the knife ever gets thinner at the spine than the thickness of the sweeping 'triangle grind' you mentioned, it would create a cross-section near the tip in which the thickest part is at the shinogi. In turn, this would make the shinogi the new 'real-spine'.
> And if you decide against allowing this to happen, the thinnest part of the spine (before reaching the grind) would have to be the same thickness as your triangle, ruling out the possibility of a taper that looks like this:
> 
> 
> 
> 
> You also run the risk of the cross-section at the heel looking like a flat-top mushroom with a sharpened stem!



Is this a theory vs practice discussion? In theory, of course I can do what @Luftmensch says, as long as the tapering spine is always thicker than the top of the primary bevel (or even if not, actually), and as long as I don’t care what happens at the tip where the top of the primary bevel becomes the spine. But maybe @Kippington is saying that it’s just hard to grind like that if you’ve already tapered the blade (or hard to grind such a taper while preserving an existing primary bevel) and there’s also no point in doing so? Or maybe I’m misinterpreting.


----------



## Luftmensch

Kippington said:


> There are definitely some things to consider: If the knife ever gets thinner at the spine than the thickness of the sweeping 'triangle grind' you mentioned, it would create a cross-section near the tip in which the thickest part is at the shinogi. In turn, this would make the shinogi the new 'real-spine'.
> And if you decide against allowing this to happen, the thinnest part of the spine (before reaching the grind) would have to be the same thickness as your triangle, ruling out the possibility of a taper that looks like this



Bingo! We're on the same page. Exactly... the way I imagine it, requires the thinnest part of the spine to be same thickness as the base of the triangle. I dont believe it could have a vanishingly acute tip.


----------



## Luftmensch

ian said:


> Is this a theory vs practice discussion? In theory, of course I can do what @Luftmensch says, as long as the tapering spine is always thicker than the top of the primary bevel (or even if not, actually), and as long as I don’t care what happens at the tip where the top of the primary bevel becomes the spine. But maybe @Kippington is saying that it’s just hard to grind like that if you’ve already tapered the blade (or hard to grind such a taper while preserving an existing primary bevel) and there’s also no point in doing so? Or maybe I’m misinterpreting.



Hehe... I am not sure what this is 

I think this would be relegated to the domain of theory. Such a volume exists but I don't think it would be an efficient usage of a blacksmiths efforts... Nor would it likely provide any material benefits. I guess it just demonstrates in _theory_ a blade could be tapered in multiple planes but achieve a consistent bevel?


----------



## Kippington

HRC_64 said:


> I'm not sure this matters in any way, 'to' and 'toward' are interchangible in this context.





HRC_64 said:


> You've already been presented with the dictionary...I suggest you actually read it.


Amazing!
Now you're committed to arguing that a line from *a* to *b* isn't required to touch *b*.
I love it!
Even if you're correct about the lexical semantics, your reasoning and arguments to back it up are hilarious!


----------



## HRC_64

Kippington said:


> If the knife ever gets thinner at the spine than the thickness of the sweeping 'triangle grind' you mentioned, it would create a cross-section near the tip in which the thickest part is at the shinogi. In turn, this would make the shinogi the new 'real-spine'.



Back to constructive comments...

Have many makers played around with maximal width cross sections with below the spine? IIRC this was not uncommon with weapons (pic below). It seems like there are mentions here and there, but was never sure if these were fully intentional or just proudction variations associated with a particular design intent.


----------



## HRC_64

Kippington said:


> Amazing!



Nah, its just pathetic at this stage you can't let go.

But keep going for it


----------



## Kippington

HRC_64 said:


> But keep going for it


Nah I'm good, it has already made my day!


----------



## Kippington

HRC_64 said:


> Have many makers played around with maximal width cross sections with below the spine? IIRC this was not uncommon with weapons (pic below). It seems like there are mentions here and there, but was never sure if these were fully intentional or just proudction variations associated with a particular design intent.


It's basically a comfort thing. We want the maximum available width at the point of contact with the user. If sword user needs to hold the base of a blade for whatever reason, a ricasso has the same effect.



They might even flair it out with a similar thing to the Wustof full-bolster, further increasing contact area with the user.



_________________________

In the case of kitchen knives, we tend to want the thickest part of the blade at the furthest point of contact from the food, doing so increases food separation. To have the thickest part of the cross-section closer to the food than necessary might be considered silly, but food release grinds might do this to take advantage of the increased food release properties. In fact the hook grind does it, but this only occurs towards the tip of the blade.



_________________________

I imagine that the reduced dorsal cross-sections you see (in the katana picture you posted above) are there for weight reduction. Efficiency of separation isn't as much of a priority when it comes to weapons.
Another way to reduce weight is to add a fuller, and you'll notice that the swords with fullers tend to have less reduction in dorsal thickness.

Also, sword users appreciate the sound and feel of the blade rushing through the air at high speed. These rear tapers help to modulate the air flowing past the blade in the same way a rear diffuser helps to control the *wake* of a car.


----------



## Nikabrik

@Luftmensch it seems like what you're suggesting is simply to introduce a compound grind wherein the two hira are not necessarily parallel, and their inclusive angle varies from heel to tip?


----------



## suntravel

HRC_64 said:


> Have many makers played around with maximal width cross sections with below the spine?



For kitchenknifes this is the old german "Walkschliff" found in some knifes from Herder today:

https://www.windmuehlenmesser.de/warenkunde/das-messerhandwerk/

Regards

Uwe


----------



## HRC_64

Aha...Like this.


----------



## suntravel

Yes, but my grinds are not the same like Herder, trying to minimize contact area of the food with more convex / concave grinds to the edge, to make sturdy blades combined with ease of cutting.

The only full flat part of the grind should be the edge its self under 0,1mm in height 

Regards

Uwe


----------



## Kippington

From what I can see through a Google translate, they don't appear to give any information on it other than 'it takes skill to make'.
I wonder if it's their version of a rounded choil?


----------



## ian

Yea, I was about to write that all they say in translation is:

"This shape gives high stability, but at the same time allows a very thin and finely ground edge."

which didn't make much sense to me. That is, rounding the spine doesn't make that any more true than it already was.


----------



## suntravel

Kippington said:


> I wonder if it's their version of a rounded choil?



nope, it is way below a rounded spine, this is made to minimize friction while cutting food 

Less contact area, less sticking or adhesion....

Regards

Uwe


----------



## Kippington

On something the size of a steak knife? That seems strange to me.


----------



## Nikabrik

ian said:


> Yea, I was about to write that all they say in translation is:
> 
> "This shape gives high stability, but at the same time allows a very thin and finely ground edge."
> 
> which didn't make much sense to me. That is, rounding the spine doesn't make that any more true than it already was.



@suntravel does "stabilität" mean "stiffness" in this context?


----------



## suntravel

Nikabrik said:


> @suntravel does "stabilität" mean "stiffness" in this context?



not realy, it means to have a easy cutting blade with some reseveve for abuse....



Kippington said:


> On something the size of a steak knife? That seems strange to me.



They are also making larger blades 

Ever used an Herder 1922, K-Chef, or K5 ? Could be a fine expirence if you get a good one, not all from Herder have the old soul since there master grinder passed away....

Regards

Uwe


----------



## HRC_64

I have actually ground a knife like this at the tip, Kono Ginsan MM w/ a robust spine and a very thin TBE edge grind...so in order to "thin" the knife, removing the "path of most resistance" leads to shaving the corner off the spine like that diagram. 

Experimentally, it worked, and was a lot less work (removed alot less metal) than if you "thinned" the knife flat on the bevel. Since the grind on that knife was so thin TBE already, flat-bevel thinning wasn't ideal. Its not clear if this is just a "life-hack" shortcut apllicable to tip area mods or if it makes sense elsewhere...My Q was an honest attempt to get more feedback.

So appreciate the contributions.


----------



## Luftmensch

Nikabrik said:


> @Luftmensch it seems like what you're suggesting is simply to introduce a compound grind wherein the two hira are not necessarily parallel, and their inclusive angle varies from heel to tip?



That is correct!

Again; I am not suggesting there is any benefit from the design! Only that it _is possible_ to have a distal taper with a constant primary bevel...


----------



## Luftmensch

Presenting the 'constant primary bevel, distal tapered' grind...

I will walk through it as seen by CAD. Note that this is completely at odds with how this blade geometry might actually be manufactured. Lets create the knife based on a chef knife/gyuto profile. The spline below represents the cutting edge:











Chose a primary bevel profile you would like to sweep across the cutting edge. In the previous example it was a simple triangle. The following image shows the primary bevel profile in green and the cutting edge profile in red (before we sweep the volume):







After sweeping the primary bevel profile down the cutting edge we end up with the following volume:






We can fill in the rest of the body as we see fit. This decision can include distal taper considerations. At the maximum height of the blade we draw what we want this silhouette to look like (shown in red):






Back to boat building... ... to render a volume from the distal taper profile (red, above) to the rectangular but curved primary bevel surface, we _loft_ from one to the other creating:






... at this point it is a weird 'blank' with a constant swept bevel and a nice distal taper. After profiling the spine:






Which isn't too bad looking! The following schematic is what the blade looks like from the right side (top left), the bottom (bottom left) and the front (top right):










To get a better sense of what is going on I have coloured the spine green, the primary bevel red and the face/hira blue. From the front:








and from the bottom:








Finally, just for fun, with tang:


----------



## HRC_64

Bravo


----------



## HRC_64

More...


----------



## Kippington

Very cool stuff! Thanks for taking the time to do this.
The bevel is quite low, is it possible to raise the shinogi and apply the same concept?
Also there is something showing up that I mentioned earlier to you specifically. If I understand it correctly, the heel of your knife has the following cross-section and so there would be no shinogi there.






Kippington said:


> Does this mean that the grind ends at the 10mm tall mark, even though the sides are flat all the way up to the spine?


----------



## ian

Kippington said:


> If I understand it correctly, the heel of your knife has the following cross-section, and so there would be no shinogi there.



Presumably that’s an accident of the particular choices made in the construction. It just so happens that the way the width of the spine was chosen, and the way the primary bevel was drawn, the grind looks like it might be flat near the heel. (However, the color picture isn’t a cross section near the heel, it’s a view of the knife looking at it from in front of the tip, so I find it a bit hard to tell.)

If the spine is chosen to be sufficiently thin near the heel, though, you’ll get a defined shinogi below it. That is, you need to choose the width of the spine at the heel to be less than what you’d get from a flat grind with the chosen primary bevel. Since you can specify the spinal width and the geometry of the primary bevel completely independently, and the rest of the grind just interpolates between these, you can do this.

@Luftmensch, how about a passaround of a 3d printed version?  I’m curious to test how it feels on the stones.

It’d be interesting to me to understand how you’d grind something like this. For instance, is there some particular way to do the interpolation between spine and bevel (what @Luftmensch is calling the lofting) that would lend itself to a straightforward grinding approach? Obviously, I have no idea what I’m talking about when it comes to grinding, though. Much respect to those of you that do.


----------



## Kippington

Oh so the cross-section at the heel looks something like this? (ignoring the colours and internal lines)




Oh man, that would be really uncomfortable.


----------



## Nikabrik

Kippington said:


> Oh so the cross-section at the heel looks something like this? (ignoring the colours and internal lines)
> 
> 
> 
> 
> Oh man, that would be really uncomfortable.


 No, the heel cross section is the blue area above. Green is the spine - it just looks funny from this perspective due to foreshortening and the spine's curve.


----------



## ian

No, that’s something else. Take your knife, paint the spine green, paint the knife red below the shinogi, and paint it blue above the shinogi. Then hold it in front of your face like you’re going to stab yourself. That’s the color picture.

Edit: +1 to Nikabrik


----------



## Kippington

Oh got it! Thanks.


----------



## Kippington

ian said:


> Presumably that’s an accident of the particular choices made in the construction. It just so happens that the way the width of the spine was chosen, and the way the primary bevel was drawn, the grind looks like it might be flat near the heel. (However, the color picture isn’t a cross section near the heel, it’s a view of the knife looking at it from in front of the tip, so I find it a bit hard to tell.)
> 
> If the spine is chosen to be sufficiently thin near the heel, though, you’ll get a defined shinogi below it. That is, you need to choose the width of the spine at the heel to be less than what you’d get from a flat grind with the chosen primary bevel. Since you can specify the spinal width and the geometry of the primary bevel completely independently, and the rest of the grind just interpolates between these, you can do this.


I agree, it works in theory and in practice, depending on all the widths and angles. The as you can imagine, the shinogi can easily get washed out if you're after both a thick spine and a thin grind at the heel.



ian said:


> It’d be interesting to me to understand how you’d grind something like this. For instance, is there some particular way to do the interpolation between spine and bevel (what @Luftmensch is calling the lofting) that would lend itself to a straightforward grinding approach? Obviously, I have no idea what I’m talking about when it comes to grinding, though. Much respect to those of you that do.


Yeah it can be a struggle sometimes, trying to balance everything we've mentioned so far. Having a defined line along a shallow angle where two faces meet is easier on paper than at the grinder.
Take a look at one I made *here* that shows a bit of taper on the 5th picture. It was a real pain in the ass to make that shinogi look good. I'm definitely lowering my shinogi/increasing my bevel angle next time.


----------



## ian

I believe it. Those pics are killer. I love the simpler aesthetics of some of the ones you’ve been putting up for sale here recently, eg the two stainless ones. I like how they look more than the honyakis, even, although maybe this is just indicating my preference in handles.


----------



## Kippington

Cheers! Those two have a different grind, the type where the shinogi drops towards the tip. I'll always prefer the performance of this over a wide bevel (more taper and less stickage) but I can't keep the shinogi defined with the knife looking like that, it just looks stupid! I had a _really _difficult time trying to convince people in an old thread that it's only an illusion - the angle of this bevel doesn't get thicker towards the tip. The angle could actually be getting thinner and it would _still _look like this, should the spine taper off into nothing. There's no way to tell from a picture alone.
Rather than repeating everything in this thread, it's easier just to hide everything by smoothing over the shinogi with a curve (which can further increase performance) and the knife ends up looking like the two you mentioned above.




_"...In the picture below the red line indicates where approximately the main convexity curve is. The blade does not have a shinogi line, but if it were to have one, this would about be where it is."_​


----------



## Nikabrik

Here's another way to view @Luftmensch's idea, with a higher shinogi:


----------



## Luftmensch

HRC_64 said:


> Bravo





Kippington said:


> Very cool stuff! Thanks for taking the time to do this.



Thank you kindly! Happy to participate in an exchange of ideas!



Kippington said:


> The bevel is quite low, is it possible to raise the shinogi and apply the same concept?



Absolutely... so long as the geometry is valid, CAD software will render it! 



Kippington said:


> Also there is something showing up that I mentioned earlier to you specifically. If I understand it correctly, the heel of your knife has the following cross-section and so there would be no shinogi there.



No. @ian and @Nikabrik beat me to it... I think they helped you visualise it?



ian said:


> Presumably that’s an accident of the particular choices made in the construction. It just so happens that the way the width of the spine was chosen, and the way the primary bevel was drawn, the grind looks like it might be flat near the heel. (However, the color picture isn’t a cross section near the heel, it’s a view of the knife looking at it from in front of the tip, so I find it a bit hard to tell.)



Exactly... I wanted the knife to look plausible.

I chose some arbitrary numbers to render the knife (for what it is worth it is a 240mm length ). By chance... or more likely because the dimensions I chose had nice numbers, yes, the heel is practically a wedge. To be precise (or at least to 32bits!) there is an angle change of 0.07 degrees. Lets just say this can be swept up as rounding error: I chose numbers that made the bevel profile and heel profile similar triangles inadvertently. But this is not a requirement - just a coincidence.



ian said:


> Since you can specify the spinal width and the geometry of the primary bevel completely independently, and the rest of the grind just interpolates between these, you can do this.



Thats right! If you conceptually separate the primary bevel from the 'body', you can make independent design decisions... _in theory_. To be fair... also in practice. However, the cost of doing it 'in practice' would be high. It would either violate large scale economics (e.g. punching out mono-steel blanks and grinding them) or be too complex to pull off (well) for craftsmen.



ian said:


> @Luftmensch, how about a passaround of a 3d printed version?  I’m curious to test how it feels on the stones.



Dont be giving me dangerous ideas 



ian said:


> It’d be interesting to me to understand how you’d grind something like this. For instance, is there some particular way to do the interpolation between spine and bevel (what @Luftmensch is calling the lofting) that would lend itself to a straightforward grinding approach? Obviously, I have no idea what I’m talking about when it comes to grinding, though. Much respect to those of you that do.



Now you have me wondering if additive manufacturing/laser sintering (see also) can produce hard enough metal structures for knifes! 

CNC milling could certainly cut a complex shape from stock material... Maybe you could do it on an unhardened billet and then get some talented folk like @Kippington to heat treat it?




ian said:


> Then hold it in front of your face like you’re going to stab yourself. That’s the color picture.



The tip straight into the eyeball!


----------



## Dhoff

Or consider casting it? Using something like C95500 nickel aluminium bronze, which is according to an article I read able to approach steel in qualities and can be heat-treated! Not able to verify myself since I have a lack of knowledge of metallugy


----------



## Nikabrik

I would think that if you freehand ground it, you would approach it one of two ways:

1) grind in a full length upper bevel that matches the heel, with no taper. Then set you taper right at the spine, before blending down.

2) do distal taper first, then grind down to a varying temporary edge thickness that gives you the right geometry (thicker at the tip).

In theory, it's essentially the same as a full flat grind from a tapered spine. In practice, I'm sure it would be a pain.


----------



## Luftmensch

My previous example was a bit subtle. Lets go 'caricature mode' so the geometry is easier to see. Lets say the spine is very much thicker than the bevel, then we have:








As a schematic; view from the back (top left), the right side (top centre), the front (top right) and the bottom (bottom centre):









And colour. Again the spine is green, the primary bevel is red and the body/face/hira is blue. View from the back:






View from the front:






and bottom:







** Caveat for the super eagle eyed: I forgot to match one dimension on the tip so there is a very _slight_ change in bevel thickness near the end. I only noticed once I started colouring the images... and eh... laziness...


----------



## Luftmensch

Dhoff said:


> Or consider casting it?



Possibly? Getting high qualities dies would be required to do thin sections. The very, very edge might be tricky!





Nikabrik said:


> I would think that if you freehand ground it, you would approach it one of two ways:
> 
> 1) grind in a full length upper bevel that matches the heel, with no taper. Then set you taper right at the spine, before blending down.
> 
> 2) do distal taper first, then grind down to a varying temporary edge thickness that gives you the right geometry (thicker at the tip).
> 
> In theory, it's essentially the same as a full flat grind from a tapered spine.



Could do? I guess it depends what access to tools a blacksmith would have. You could do it in a machine shop with mills etc...



Nikabrik said:


> In practice, I'm sure it would be a pain.



Ha! Amen! There would have to be a compelling reason to bother!


----------



## Jville

labor of love said:


> Oh it’s okay. Should’ve tried the standard instead of workhorse back in the day.



I've only used one of each, but in my experience, the workhorse definitely had more taper. It was quite beautiful. The standard was much closer to takayuki ginsan.


----------



## Luftmensch

One more in 'plain silly mode'. Lets say the primary bevel is relatively fat and the distal taper is reversed (thin at the handle, thick at the tip):








As a schematic; view from the back (top left), the right side (top centre), the front (top right) and the bottom (bottom centre):








And colour. Again the spine is green, the primary bevel is red and the body/face/hira is blue. View from the back:






View from the front:






and bottom:


----------



## labor of love

Jville said:


> I've only used one of each, but in my experience, the workhorse definitely had more taper. It was quite beautiful. The standard was much closer to takayuki ginsan.


I solved the problem by commissioning a custom maker to copy Kato standard profile but with added height and length, and distal taper.


----------



## ian

Pretty sure he’s talking about Kippington. 

But whatever, @Sharpchef, you’re being kind of troll-y here. If you actually read the thread, you’ll see that

1) Uwe made a very valid point about the progression of the grind being important independent of the distal taper along the spine,

2) after a little bit of confusion due to a conflict of terminology in the way Uwe was expressing his point, Kippington agreed that certainly that was the case, and said he’d focused on distal taper along the spine for simplicity of exposition. 

Then there was a lot of bringing up that same point over and over again, even though it had already been resolved, and a lot of associated nonsense posts, interspersed with a couple more good comments by Kip and others on how distal taper affects other things in the knife making process, etc... 

Please don’t contribute inflammatory remarks that don’t reflect the actual content of the thread.


----------



## labor of love

I think if the thread was titled “understanding spinal distal taper” that would’ve cut out about 90% of the poppycock.


----------



## ModRQC

Wow... I never thought my post would even be noticed...

Well then...

@HRC_64 contrarily to what you think, I initially took your post about boats as a conceptual argument, and I really liked it. In fact, from the beginning I was wondering why the discussion was only about the taper at the spine, and that surely the whole of the knife was also concerned. And your post brought answers to that wondering, and Kippington admitted that he should have explained more clearly that it was a mean of simplification. And it all made sense to me. Then, it seems that all you wanted was to bash on him and anyone else defending the validity of his post... which most of them did still taking in your point, but understanding too that Kippington was simplifying for the sake of a discussion... "_understanding_ distal taper" might very well be done, indeed, by focusing first and foremost on the spine. No one said that your own post was wrong or unrelated; they just still thought his thread was valid too! No one bashed at you at that point; the worst that was said was to let go of the boat argument a bit... That's when most of the points you made were not conceptual anymore, but arguing terminology and trying to prove the whole idea wrong because Kippington didn't use "spinal" in his thread title. And you were right, in the absolute, he should have, and your whole point was valid, and was thoroughly discussed I think when others contributed "models" of blade where the spinal taper wouldn't come close to tell the whole story or even be representative of the blade. But man... chill out. What has he done to you?

I'm glad to see though that since then the discussion got quite interesting again, and focused too. It's a great thread to read, and it's gotten so far that I'll have to start from the beginning, tuning out the "distractions" and absorbing the data. And I really think all of you made at least one point to help me understand many many things, and that's why a forum can bring so much more insight to a concept than any professional review, guide and whatnot can manage.

Which brings me to what I really wanted to say the first time around: thanks to Kippington, and thanks to all contributors, to the time invested in really precise cuts of the subject... bad pun shamelessly intended.


----------



## ma_sha1

Old thread, but extremely relevant still. I just learned an important lesson on distal taper first hand.

I’ve been aware for a while that Choil shot is very misleading, but I’ve always trusted spine shot. I was not aware that distal taper, commonly represented by spine shot, can be equally misleading until I cut open a Nakiri.

The spine view showed a beautiful killer distal taper from heel to tip, but the taper is not there once I cut open the front spine, in fact, the front of the knife had “reverse distal taper” below the spine, I.e., the knife below spine is actually thicker towards the front.

The spine distal taper from the top down view was nothing but an optical illusion, achieved by increased rounding of the spine towards the front. Theres’s zero function as it did not get carried down into the grind. 

I think the extra weight out front might make Nakiri chops better than a Gyuto, but that’s beyond the point.

I never thought that “beauty is only skin deep” applies so well to kitchen knives. The sad thing is, we’ll continue to rely on choil shots & “distal taper” spine shots for remote purchases decisions. Unless someone has a better idea?


----------

