# Thickness behind the edge



## krx927

What do you say about the thickness behind the edge of my 210mm Akifusa gyuto? 

Until now I was sharpening it on EdgePro and I have noticed quite some shoulder developing. As I recently switched to free hand I said I will try to thin it a bit. After that I was checking the thickness behind the edge and to me it still looks a bit thick. At least the majority of shoulder is gone now.

What do you say experts?


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## Pensacola Tiger

How does it cut? That's the true measure of your thinning efforts.


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## JBroida

for me, i would thin quite a bit more


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## panda

call jenny craig


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## chinacats

needs some thinning still...not the best pic, but this is a 240 Gesshin Kagero. I've thinned it a little bit, but it was much thinner than yours out of the box.


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## Chuckles

I have a couple of knives that are are almost that thick that I like quite a bit. If you are happy with how it cuts for now take some time using it so you get to know the changes you are making to it. It can certainly get much thinner if you want to put in the time.


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## labor of love

Sometimes long thinning sessions can be a PITA. If I were you I would just thin 20 minutes or so every time you sharpen. If you pay close attention, you'll be able to feel and see the differences in your cuts gradually overtime. Either way, if your thinning technique is decent enough keep putting in the work, the blade could cut better for sure.


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## Kippington

The stage at which you want to stop thinning is up to you as the owner/user to answer, but that's hard to know if you've never done it before.

A great idea for your first thinning attempt is to get a cheap knife made from an easily grindable soft steel with a similar blade geometry to your Akifusa and try thinning that out first. Every so often during the process you can take a break and use the knife for food prep, feeling out how the behavior of the knife changes over time. Sure, it won't be exactly the same as when you start your proper attempt on your Akifusa, but you'll learn a hell of a lot in a much shorter time frame.

Also on a cheap knife it is safe to get really carried away and go overboard too. I did just this to see how a knife will handle past its 'optimal' thinness and into the realm of the anorexic laser. :biggrin:


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## krx927

Thanks for the answers. I had a feeling it is not yet thin enough.

Like you are mentioning it is pretty hard to judge if you have never done it before 

On the other hand, yesterday when I sharpened it, for the first time I was able to get a knife to hair whittling sharpness. I was really happy seeing that hair being cut in two 

Can I ask you one other question about thinning: when I was checking Jon's thinning video he was doing it on a knife with pronounced secondary bevel, saying that thinning should be done only on this bevel. With a knife like this it is pretty easy to define the thinning area and hold correct angle. Unfortunately majority of my knives (Akifusa included) do not have a clear secondary bevel. In my thinning attempts I was holding such angle that I remove material approx. 1cm from edge:






Should I also remove material higher up the blade using more flat angle when I grind?

In any case I will now use it a bit to see how it performs and will attempt thinning at some other time.


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## Mangelwurzel

Kippington said:


> The stage at which you want to stop thinning is up to you as the owner/user to answer, but that's hard to know if you've never done it before.
> 
> A great idea for your first thinning attempt is to get a cheap knife made from an easily grindable soft steel with a similar blade geometry to your Akifusa and try thinning that out first. Every so often during the process you can take a break and use the knife for food prep, feeling out how the behavior of the knife changes over time. Sure, it won't be exactly the same as when you start your proper attempt on your Akifusa, but you'll learn a hell of a lot in a much shorter time frame.
> 
> Also on a cheap knife it is safe to get really carried away and go overboard too. I did just this to see how a knife will handle past its 'optimal' thinness and into the realm of the anorexic laser. :biggrin:



Kippington - that's a sweet looking grind. What's the knife?


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## 420layersofdank

Kippington said:


> The stage at which you want to stop thinning is up to you as the owner/user to answer, but that's hard to know if you've never done it before.
> 
> A great idea for your first thinning attempt is to get a cheap knife made from an easily grindable soft steel with a similar blade geometry to your Akifusa and try thinning that out first. Every so often during the process you can take a break and use the knife for food prep, feeling out how the behavior of the knife changes over time. Sure, it won't be exactly the same as when you start your proper attempt on your Akifusa, but you'll learn a hell of a lot in a much shorter time frame.
> 
> Also on a cheap knife it is safe to get really carried away and go overboard too. I did just this to see how a knife will handle past its 'optimal' thinness and into the realm of the anorexic laser. :biggrin:



WHOA!!! HOW DOES SHE CUT?


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## rick alen

Your Akifusa is a bone-splitter at the moment. A $20 pair of verniers will tell you just how thick you are. .015"/.38mm is still thick enough for a work horse, I prefer >.010" for 99% of what I do.

Speaking of thinning cheap knives, I thinned some very soft stainless to about .008" and the other day I was cutting around some ribs with it, I didn't think I made much contact with bone but there appeared 2 sizeable dimples bent into the edge.


Rick


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## chinacats

krx927 said:


> Thanks for the answers. I had a feeling it is not yet thin enough.
> 
> Like you are mentioning it is pretty hard to judge if you have never done it before
> 
> On the other hand, yesterday when I sharpened it, for the first time I was able to get a knife to hair whittling usharpness. I was really happy seeing that hair being cut in two
> 
> Can I ask you one other question about thinning: when I was checking Jon's thinning video he was doing it on a knife with pronounced secondary bevel, saying that thinning should be done only on this bevel. With a knife like this it is pretty easy to define the thinning area and hold correct angle. Unfortunately majority of my knives (Akifusa included) do not have a clear secondary bevel. In my thinning attempts I was holding such angle that I remove material approx. 1cm from edge:
> 
> 
> 
> 
> 
> 
> Should I also remove material higher up the blade using more flat angle when I grind?
> 
> In any case I will now use it a bit to see how it performs and will attempt thinning at some other time.



I'm guessing that the original bevels (thinning bevels) were lost by using the EP? My Kagero had very easy to feel thinning bevels--just put the knife down and it told you where to thin. I believe you're on the right track and once you establish bevels this make it much easier to continue.


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## Pensacola Tiger

krx927 said:


> ...one other question about thinning: when I was checking Jon's thinning video he was doing it on a knife with pronounced secondary bevel, saying that thinning should be done only on this bevel. With a knife like this it is pretty easy to define the thinning area and hold correct angle. Unfortunately majority of my knives (Akifusa included) do not have a clear secondary bevel. In my thinning attempts I was holding such angle that I remove material approx. 1cm from edge:
> 
> 
> 
> 
> 
> 
> Should I also remove material higher up the blade using more flat angle when I grind?
> 
> In any case I will now use it a bit to see how it performs and will attempt thinning at some other time.



Yes, try a shallower angle and thin at least the lower third of the blade.


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## Framingchisel

I use a micrometer set to 25 thousands as a starting point and adjust from there. This video says most of what you need to know.
[video=youtube;WrCo4Vg2iiI]https://www.youtube.com/watch?v=WrCo4Vg2iiI[/video]


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## Benuser

After some EP use blades become thicker behind the edge. Great edges, poor cutters. Not easy to correct at once. That's how I understand Rick's suggestion to thin up to a third of the blade's width. When properly sharpening from the beginning on, you should be all right when you start behind the bevel. I would suggest the lowest angle you can perform for the relief bevel.


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## Benuser

Please be aware that after heavy thinning the edge may require a slight correction. With less steel behind the edge a higher sharpening angle may be necessary for edge stability.


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## rick alen

Benuser said:


> Please be aware that after heavy thinning the edge may require a slight correction. With less steel behind the edge a higher sharpening angle may be necessary for edge stability.



I wouldn't think you'd need to use a higher angle. The stability of the edge itself, what's in front of where the primary bevel begins that is, is really not affected by what's behind it. If you took the thinning down to .001", it would be that .001" thickness causing the instability, not the primary bevel.

It should be understood that if your edge was 10deg inclusive there would be no need to thin behind that edge at all, unless you're going through a large gourd, which is unlikely what you'd use that edge for. I believe that is [true] single-bevel knife territory like usuba's. But at 20deg inclusive+ where we typically sharpen that is where I feel the thinning becomes noticeable.


Rick


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## Kippington

rick alen said:


> I wouldn't think you'd need to use a higher angle. The stability of the edge itself, what's in front of where the primary bevel begins that is, is really not affected by what's behind it. If you took the thinning down to .001", it would be that .001" thickness causing the instability, not the primary bevel.
> 
> It should be understood that if your edge was 10deg inclusive there would be no need to thin behind that edge at all, unless you're going through a large gourd, which is unlikely what you'd use that edge for. I believe that is [true] single-bevel knife territory like usuba's. But at 20deg inclusive+ where we typically sharpen that is where I feel the thinning becomes noticeable.



I completely agree with this comment.



Mangelwurzel said:


> Kippington - that's a sweet looking grind. What's the knife?





420layersofdank said:


> WHOA!!! HOW DOES SHE CUT?



It's a re-profiled Richmond GT Artifex 210mm Wa-Gyuto, which I wouldn't suggest anyone buy unless they wanted something to experiment on.
Although, in her current state she cuts very nicely indeed! :biggrin:










Sorry for slight thread derail.


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## Salty dog

I often wonder why people feel compelled to "thin the edge"? I often wonder if people know what they are doing?


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## XooMG

Salty dog said:


> I often wonder why people feel compelled to "thin the edge"? I often wonder if people know what they are doing?


Some do.


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## JBroida

XooMG said:


> Some do.



many dont


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## XooMG

JBroida said:


> many dont


C'mon Jon...you've read my messages. Let me be optimistic for once.


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## JBroida

you should see the number of knives that come to me after supposed thinning that look like battle axes


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## Devon_Steven

Salty dog said:


> I often wonder why people feel compelled to "thin the edge"? I often wonder if people know what they are doing?



That's a new expression to me! My first impression is that thinning the edge = sharpening.

So, what are people trying to (misguidedly) achieve when they attempt to ' thin the edge'?


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## Mrmnms

It's not so much what they're trying to do, which carefully removing metal behind the edge to improve cutting performance. I've seen some knives that were pretty trashed from over aggressive or uneven attempts to do this without much regard to the original profile or actual goal in mind.


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## Devon_Steven

Thanks, I get it now


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## Kippington

To salty and JBroida, I think I may have been totally misunderstood, and by the two people I look up to the most on this forum as well.

What I've tried to say in my previous posts is that the knife I've pictured has been an experiment; a cheap knife I didn't like that I sacrificed for a gain in skill and understanding. Much like how a bladesmith might test different heat treats on the same steel till destruction, I wanted to test how a blade would behave past it's 'ideal' thickness, and how that would translate into the kitchen.
It's been a great learning tool for me, hopefully bringing me one step closer to the level of your collective knowledge (this I don't actually know), and I was only suggesting to the OP to consider doing the same.

Or maybe I'm misunderstanding the situation myself - the last few posts have been very vague, and I've also had a pretty rough day at work (four steaks sent back tonight, all apparently undercooked).


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## wphill

Caution by Jon and Xoomg has gotten my attention. Originally, I thought..how can I thin a knife when I hardly feel or see the bevel. Then, I gave myself the opportunity
to practice on a Henckel...which wowed me. I still don't know if I was lucky or instinctively had a feel. Probably, something along the lines that one can't mess up an overly
thick behind the edge knife. Next, I thinned a nakiri that had a wonky grind. Again, when the knife is one down to begin with, I guess it's less likely that I can mess up.

In my head, I have had the assumption that the following precautions keep me in bounds: take pictures, study them, do a little ans re-examine...along the way use a sharpie and use a caliper.

As I upgrade my knives, time to not let some positive experiences go to my head. Then again, these are knives that I hope I only thin within the narrow definition of sharpening.
And, if I want to get aggressive time to revisit Jon's videos.


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## JBroida

Kippington said:


> To salty and JBroida, I think I may have been totally misunderstood, and by the two people I look up to the most on this forum as well.
> 
> What I've tried to say in my previous posts is that the knife I've pictured has been an experiment; a cheap knife I didn't like that I sacrificed for a gain in skill and understanding. Much like how a bladesmith might test different heat treats on the same steel till destruction, I wanted to test how a blade would behave past it's 'ideal' thickness, and how that would translate into the kitchen.
> It's been a great learning tool for me, hopefully bringing me one step closer to the level of your collective knowledge (this I don't actually know), and I was only suggesting to the OP to consider doing the same.
> 
> Or maybe I'm misunderstanding the situation myself - the last few posts have been very vague, and I've also had a pretty rough day at work (four steaks sent back tonight, all apparently undercooked).



my response was more to salty... i have a lot of people who send in knives for sharpening and they will say something like, "i've thinned this knife really well, so it just needs an edge put on it." Then, i look at the knife, and its thicker behind the edge than the first picture in this thread. Some people misunderstand thinning as simply knocking off the shoulders of a bevel. Or others than only thin about 1-2 mm above the edge, which has almost no impact on the thickness in the middle of the blade.

Anyways, my comment was not in response to anything you said, so no misunderstanding there.


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## chinacats

I found a few pics of the thinning session on my Kagero--hopefully will be helpful to op as to whereabouts to thin on the Akifusa. Again this is my Gesshin Kagero (believed to be Akifusa but with Jon's added specs). I should note that this knife was thinned prior to any sharpening sessions so not so much the same situation as the op. I planned on having this knife re-handled so figured I would do it prior to any potential scratching, etc when removing the old handle. Another reason was that I had a chance to try out a couple of Jon's coarse stones on this knife so on the face side is Gesshin 400 and on the other side is Gesshin 220. Pics aren't the best but you can likely tell the difference in the scratch pattern. The 220 was definitely faster but man that 400 sure did a nice job--fast and not too much cleanup left as opposed to the 220.

I never was too good at coloring in between the lines...












current finish (800 grit wet/dry)






and finally, the new shoes:


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## wphill

I watched the video on using a micrometer. While I like the concept I would prefer one to demonstrate it as they are using
it while thinning a j.knife. Myself, I own a caliper and like to use mm as the metric. To take a step further, a demonstration on
knives with significantly different grinds would be quite educational.


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## schanop

LOL, Jim.

I tought for a bit that you intentionally put a serrated edge on the knife.



chinacats said:


> current finish (800 grit wet/dry)
> 
> 
> 
> 
> 
> 
> and finally, the new shoes:


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## panda

China at, why are you using stainless?? &#55357;&#56835;


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## chinacats

schanop said:


> LOL, Jim.
> 
> I tought for a bit that you intentionally put a serrated edge on the knife.



Chanop, best damn bread knife ever. Didn't realize what you were talking about until I looked at the pic--made me question it myself.:lol2:



panda said:


> China at, why are you using stainless?? &#65533;&#65533;



Have to own at least one stainless gyuto and this is the one I currently picked...I like it so far. The only other stainless clad knife I've owned was a semi-stainless Heiji and I actually prefer this cladding to that though I'm not sure I can say why. I did prefer the Heiji overall, but the core steel on this Kagero is ridiculous.


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## panda

cool, did chris do the handle for you?


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## chinacats

panda said:


> cool, did chris do the handle for you?



Tilman!


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## panda

you sent it all the way over to germany??


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## chinacats

panda said:


> you sent it all the way over to germany??



I had a package going that way anyway so the only extra shipping was the return journey. Tilman's work is top notch and now my knife is just a bit more worldly


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## wphill

Handsome knife! I'd like to hear more about the core of your Kagero.

Also, curious to hear more numbers about thickness behind the edge
and how far above you are taking that measurement. MM's preferred.

I hope Jon will weigh in and share more about the common mistakes that he sees
from rookies like me. I'm hooked on thinning my knives to make both make them better
and to do as part of sharpening. But, I dread making something worse out of plain
stupidity.


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## rico

Nice photos . . . Jenny Craig eat your heart out !!


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## krx927

Thanks for all advises posted. I still have a long way to go to really learn all the aspects of maintaining the knifes, but slowly I am getting there  
But I would really like to thank all the experienced members on this forum for all the inputs and attitude toward us newbies. Every time a question is asked it is promptly answered and nobody is putting the attitude like on other (non knife releted) forums. Not even once I saw anybody answer: use search or this was debated already many times and similar...
Thumbs up gents!

I think I will leave my Akifusa for the moment and not continue thinning as I put really nice finish with 1200 wet/dry paper. BTW this part was so much easier than thinning. I will continue thinning when it will need sharpening...
Now I need to tackle my Miyabi, it's even thicker than Akifusa


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## chiffonodd

chinacats said:


> needs some thinning still...not the best pic, but this is a 240 Gesshin Kagero. I've thinned it a little bit, but it was much thinner than yours out of the box.



This is timely - I was just about to ask, what happens with the soft cladding and core steel when you thin a knife like this? Do you end up exposing a significant amount of core steel? If so is that a problem?


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## JBroida

more core steel can be exposed, but its not a problem.

Here's an example from my instagram account of what thinned knives should look like behind the edge... in my opinion at least. Here are 3 i just finished... the first one was just rounding and polishing the spine and choil, but the later two were thinned and refinished.

https://instagram.com/p/0BKubGKpNp/?modal=true


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## Pensacola Tiger

chiffonodd said:


> This is timely - I was just about to ask, what happens with the soft cladding and core steel when you thin a knife like this? Do you end up exposing a significant amount of core steel? If so is that a problem?



Done correctly, a bit more of the core is exposed, but this is not a problem. To illustrate, here is a photo from Dave Martell's subforum showing a Hiromoto before and after thinning (and etching):


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## chiffonodd

JBroida said:


> more core steel can be exposed, but its not a problem.
> 
> Here's an example from my instagram account of what thinned knives should look like behind the edge... in my opinion at least. Here are 3 i just finished... the first one was just rounding and polishing the spine and choil, but the later two were thinned and refinished.
> 
> https://instagram.com/p/0BKubGKpNp/?modal=true



Awesome stuff - thinning a gesshin ginga jeez it must freakin split atoms now.


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## chiffonodd

Pensacola Tiger said:


> Done correctly, a bit more of the core is exposed, but this is not a problem. To illustrate, here is a photo from Dave Martell's subforum showing a Hiromoto before and after thinning (and etching):
> 
> View attachment 26711



"Done correctly" being the key  so how high up the blade would you go? I've got murray carter's DVDs on sharpening but the thinning technique covered there has you lay the blade flat on the stone. that would reach as high up as possible. Would you raise the spine so that you're only thinning a certain distance up the blade height?


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## Pensacola Tiger

chiffonodd said:


> "Done correctly" being the key  so how high up the blade would you go? I've got murray carter's DVDs on sharpening but the thinning technique covered there has you lay the blade flat on the stone. that would reach as high up as possible. Would you raise the spine so that you're only thinning a certain distance up the blade height?



I can't speak for Murray or anyone else, but I thin no more than the lower third of the blade in most cases. Yes, to do it that way, you raise the spine. One exception I can think of offhand was an Artifex that went over halfway.


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## chinacats

JBroida said:


> Here's an example from my instagram account of what thinned knives should look like behind the edge... in my opinion at least. Here are 3 i just finished... the first one was just rounding and polishing the spine and choil, but the later two were thinned and refinished.



Jon, what are those knives and what did they look like before thinning. They both look almost anorexic Do you thin your own knives that much?


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## wphill

Jon...I agree with chinacats..."anorexic"...far thinner than what I expected. Were you trying to follow the wishes of a customer vs
what you would have done yourself? For higher end knives...for me that's anything over 150.00:biggrin:... I would worry about messing
with the vision of the knife maker's grind. Beautiful work. Thanks for sharing your pictures. I think that well love pictures.


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## JBroida

Both of the thinned knives were for a customer that likes thin knives, and the steel/ht on both that i worked on were capable of holding these kinds of edges. I like mine this way too, but clearly its not for everyone. However, it is closer to what thinning should look like than what i often see referred to as "thinned".


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## panda

looks like customer just wants razor blade and not kitchen knives.


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## JBroida

honestly, i dont have a problem with how thin they are... the knives can easily handle it, and i have many knives in my personal collection that are as thin. Some people like thin, and others dont. The reason i posted is because i feel people have a misconception of what thin is, and what thinning actually means. Its not just knocking off shoulders and smoothing things out. Its an entire regrind of the blade, making significant changes to cross sectional geometry.


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## panda

i agree with that, but most people aren't going to understand what 'cross sectional geometry' is, and many that think they do actually dont. i'm not sure photos are going to help alleviate the confusion either unless you blow it up like 5x magnification and break down what is going on in detail but in laymans terms...


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## Timthebeaver

wphill said:


> I would worry about messing with the vision of the knife maker's grind.



I do wonder how many garage tinkerers with a knowledge base comprised mainly of reading and looking at stuff on the internet can actually improve the geometry created by an craftsman who spends his life grinding blades. Which got me thinking why there are fewer passarounds these days, and the number of passround knives where the geometry was damaged/ruined by "experienced" sharpeners and their work. However, I guess if you own the knife and you want to change the geometry that's your prerogative.

I remember (going way back when) there was a craze for thinning Takedas down to nothing (when they were very thin to start with) with no respect to the subtleties of the original grind. I guess for some, the ability to "fall though food" will trump everything else, even if it makes the knife a less effective tool.

Jon, as others have mentioned, that is some fine work.


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## chiffonodd

JBroida said:


> honestly, i dont have a problem with how thin they are... the knives can easily handle it, and i have many knives in my personal collection that are as thin. Some people like thin, and others dont. The reason i posted is because i feel people have a misconception of what thin is, and what thinning actually means. Its not just knocking off shoulders and smoothing things out. Its an entire regrind of the blade, making significant changes to cross sectional geometry.



An understanding that I'm sure takes many years of dedication to truly develop. I can only speak for myself, but as an overworked desk jockey who's come to love learning about cooking and knives as an awesome hobby and break from the drudgery of it all, I'll continue to have fun knocking off shoulders and smoothing things out  and then I'll send it off to the pros like you to fix my amateur mistakes. until I get it all figured out of course . . . so . . . maybe in a decade or two. that's all it should take, right?


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## chiffonodd

Timthebeaver said:


> I do wonder how many garage tinkerers with a knowledge base comprised mainly of reading and looking at stuff on the internet can actually improve the geometry created by an craftsman who spends his life grinding blades.



I would hope that amateurs (myself very much included) would know where to draw the line. I can look stuff up online, watch videos, and tinker around with my MAC but I would never mess with a shigefusa or gesshin kagekiyo, or other craftsman knife. . . Not for a very long time.

But you gotta learn on something, right??


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## Keith Sinclair

Timthebeaver said:


> I do wonder how many garage tinkerers with a knowledge base comprised mainly of reading and looking at stuff on the internet can actually improve the geometry created by an craftsman who spends his life grinding blades. Which got me thinking why there are fewer passarounds these days, and the number of passround knives where the geometry was damaged/ruined by "experienced" sharpeners and their work. However, I guess if you own the knife and you want to change the geometry that's your prerogative.
> 
> I remember (going way back when) there was a craze for thinning Takedas down to nothing (when they were very thin to start with) with no respect to the subtleties of the original grind. I guess for some, the ability to "fall though food" will trump everything else, even if it makes the knife a less effective tool.
> 
> Jon, as others have mentioned, that is some fine work.



I like thin knives for many jobs. Agree with you Tim there is a tradeoff less steel wears down faster & you have to be careful of what kinds of foods you cut. But it is worth it with precise cutting jobs that demand a thin sharp blade like Panko & breaded items. The list goes on. You don't have to baby them as long as you take care of the edge.

If you want a thin blade they are available some Carters are very thin. The Sakai special thin another . I thought only the Japanese have the B#@ to grind blades that thin. So if you want a thin blade just buy one instead of grinding down blade faces esp. for garage tinkerers. I think better to leave major thinning to the pro's. Also many knives that are not the laser type can be good cutters. Just because you read on forums about thinning doesn't mean you have to do it to make a knife cut better than stock. 

A thinning bevel close to the stone sets up the final bevel. Works for thick & thin blades. Ultra thin blades demand exceptional knife care. Look at the beating Shuns take just because they are so available.


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## Benuser

Before performing heavy thinning, correct steering as in post nr 109, and verify again from time to time. That said, steering will normally decrease with a thinner blade, but you have less material left for compensating.

http://www.kitchenknifeforums.com/showthread.php/5656-Asymmetry--The-REAL-DEAL/page11


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## wphill

I'm still scratching my head...'cross sectional geometry'? Kind of like a cross section between sculpturing and physics?
I just had an all carbon white no.2 Yusuke come from Japan. Not the special, but Jon could make it one. Kind of funny
if it was to backtrack a few thousand miles. This thread is a reminder that a picture sparks volumes.


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## Ruso

Many knives do not come new as thin as Jon's pictures. Does it mean that many many makers do not know what they are doing or just slacking off? 

Also, do you thin the whole blade at some point to maintain relative thickness across the plain?


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## XooMG

Nice work Jon. I don't see any problem with them.

Perhaps with my background I take it for granted, but I feel like we should be encouraging the so-called "garage tinkerers" rather than trying to shame them and claim they are unworthy to question the "masters" who make their knives.


Ruso said:


> Many knives do not come new as thin as Jon's pictures. Does it mean that many many makers do not know what they are doing or just slacking off?


Unless a maker knows what you want, they will make what works for their overall customer base with the fewest complaints, or to their own preferences. In either case it is not necessarily wrong to desire something a bit thinner and a little more delicate than the maker's stock product.


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## wphill

OKay...I'm going to let the shock settle...as in "I could never do what Jon has accomplished..it's like major surgery" to "well maybe, as I get to know a particular knife and can
envision how it can be better" I just might work on the Ysuke. It's all carbon, no SS to grind through. (I'm taking a cue from XooMG)

Curious...what kind of numbers are associated with the thinness of Jon's knives? Can I entice anyone to play along?
I'm going to guess...number in mm and in progression from edge to a little higher than the first third of the blade:
.05--.15---.10---.35----.55
This is for the first of two knives thinned (Geshin?)This first one seems to be very slightly concave. The second knife(Kramer?) displayed strikes me as having more a flat grind...gradually increasing in thickness with neither being concave or convex. I won't even try to guess as to symmetry or asymmetry of the primary bevel, nor presence of micro-bevel..which I think could be a given from added strength.


----------



## JBroida

Ruso said:


> Many knives do not come new as thin as Jon's pictures. Does it mean that many many makers do not know what they are doing or just slacking off?
> 
> Also, do you thin the whole blade at some point to maintain relative thickness across the plain?



as XooMG mentioned, most makers are shooting for a happy medium. I've watched the same craftsmen thin blades like i do (in fact, they are some of the guys i train under for sharpening)... Of course, it all depends on the end user and what he/she wants and is capable of handling.

When thinning, you will eventually have to thin the entire blade (and this happens during my refinishing). This is especially true for knives that are already on the thicker side at the spine.

In addition, i dont think people necessarily need to shy away from things like this... in fact, i feel like i encourage the opposite most of the time. I try to put as much info out there as i can. I just hope that people can be a bit more critical about their own abilities and where they stand before taking on a project like this. The fact is, there are very few things people can do to truly mess up their knife permanently, and most of the non-permanent things can be fixed by a professional if push comes to shove, so there's no reason for people to stop trying. I just got tired of hearing from people about their thin knives and how they thinned the crap out of their knife, but then, when i see it, it looks like a battleaxe.

Also, cross sectional geometry refers to how a knife tapers from edge to spine. Here's what i'm talking about:






In terms of specific measurements, i did not measure, but i would be happy to do so in the future. Both thinned blades feature a convex grind, though the lower section is a bit flatter. They also both feature primary bevels that will support that kind of geometry. Sorry the video wasnt better quality, but next time, i'll try to take nicer pictures so you can more clearly see whats going on.


----------



## Dardeau

My advice is to buy a ku Itinomonn as a practice thinning knife, rather than the Yusuke. Thinning monosteel lasery knives is much less intuitive to me, clad knives where you have a bit of guidance and wiggle room are easier.


----------



## wphill

Dardeaux,
Trust me, I'm half-chicken to being with . I can hold off on the Yusuke. I did take on two nakiri's and one santuko, but as Jon points out I didn't
go as far up the blade as he did. I am guessing that I went fairly thin but only up 5mm from the edge...whereas Jon went ...2 to 3 x that distance. I'm only
pointing the area that I wanted under .50mm thick. As for the rest of the blade actually hitting the stone, one third up and that's it. I didn't scratch
the whole blade. That sounds more daunting than thinning above the edge, as it will then ...I presume, require polishing out scratches and undoing the rough
original finish (scale). When it comes to performance, I don't yet have a knife that when I lay down half of an onion my initial horizontal strokes are not gliding through
from one side to the other. Being just a home cook, this could be technique. Good thread. Jon is very generous in sharing his time.


----------



## JBroida

yeah... cleaning up the scratches on the sides is actually by far the most time consuming part


----------



## Benuser

For carbon lovers not. Have an equally rough finish with coarse Scotchbrite and put a patina on it. But I'm aware that's playing in a rougher league.


----------



## JBroida

clearly you've never had the pleasure of thinning and refinishing honyaki knives


----------



## Benuser

Certainly not! I fully admit it's a gross procedure, and far from adequate with finer knives. But will work for average Western kitchen work.


----------



## XooMG

JBroida said:


> In terms of specific measurements, i did not measure, but i would be happy to do so in the future. Both thinned blades feature a convex grind, though the lower section is a bit flatter. They also both feature primary bevels that will support that kind of geometry. Sorry the video wasnt better quality, but next time, i'll try to take nicer pictures so you can more clearly see whats going on.


Don't fret about the video; the quality was good. Even in good photos, there's generally an illusion that gives the impression of concavity when the convex is subtle enough. It can be overcome easily enough by mobile users who can tilt their phones and sight down the lines, but on a standard screen it's harder. I recently had the same issue crop up in another thread.


----------



## wphill

Scocthbrite? You lost me. Is this an easy fix to the scratch issue though not a pristine one? That's ok with me. Feel free to elaborate.


----------



## Benuser

The idea is getting a relatively coarse, even surface that allows fast patina building. In the picture a soft stainless clad blade treated with Scotchbrite to give an idea of the grit. Must be about JIS400.
The left blade is a carbon after thinning, treated with Scotchbrite. Patina except for the edge area where the Scotchbrite hasn't been -- it would have destroyed the edge in one single stroke.


----------



## chinacats

Green Scotchbrite is as close as I could get to the original Shig finish...


----------



## Zwiefel

chinacats said:


> Green Scotchbrite is as close as I could get to the original Shig finish...



I've heard green scotchbrite discussed many times on the forum, but since i didn't have any polishing projects to do, I haven't really chased it down.....until now. Is this what you are talking about?:

http://www.amazon.com/dp/B00978XCOW/?tag=skimlinks_replacement-20


----------



## wphill

Benuser...nice picture!! Interesting. So...even though it's "stainless"..soft enough that the scotchbrite exposes the carbon core for the patina to build?

For me, I'm trying to plan ahead. Does this sound right?....
Thin a carbon core knife, give a sigh of relief that it looks right, 
then deal with the scratches...scothbrite lower grit like 400 equivalent,
then sharpen the edge,
then let the patina build. 

You've mentioned soft stainless steel clad, what about a mono steel white no.2?
Same thing but higher grit...800?

And, on the to-do list is to thin this one:
Shibata Kotetsu Bunka 175mm. Made by Takayuki Shibata with R2 steel.
It has soft stainless (R2?) cladding... scratches very easily. Looks pristine
as new but merely stropping, washing, an drying left some scratches....I think
the stropping picked up some grit..errr. My only R2 steel...all the others are
white carbon..so this is new to me. Well, it's all new to me. I do like this
particular knife and would like it to look less "stainless" whereby its' finish
does not allow shallow scratches to stand out as an eye sore. My thought
is to give it a matte finish by polishing it with w/d sandpaper progressing
600 t0 1200? Or, use some saved medium stone grit from flattening as a
first application.

Thinning means dealing with the entire blade. Thinking out loud in hope of pointers
from the more experienced.


----------



## chiffonodd

wphill said:


> And, on the to-do list is to thin this one:
> Shibata Kotetsu Bunka 175mm. Made by Takayuki Shibata with R2 steel.
> It has soft stainless (R2?) cladding...



So R2 would actually be the core steel - one of the PM steels, like SRS15. Just FYI!


----------



## Benuser

No, a misunderstanding. The stainless clad was only to show the grit of the Scotchbrite finish.
The Scotchbrite I used is the brown/mauve one.


----------



## Benuser

By the way, I wouldn't sharpen before having forced the patina. Hot vinegar and other acidic stuff will dull an edge.


----------



## chinacats

Zwiefel said:


> I've heard green scotchbrite discussed many times on the forum, but since i didn't have any polishing projects to do, I haven't really chased it down.....until now. Is this what you are talking about?:
> 
> http://www.amazon.com/dp/B00978XCOW/?tag=skimlinks_replacement-20



Z, I use the green scrubbies with yellow sponge attached but guessing the green part may be the same shown, just not sure. I grab them at the grocery or Home Depot.

The brown ones Benuser used are more coarse while the blue are much softer...which one to use would depend on how hard/soft the cladding is.


----------



## Zwiefel

chinacats said:


> Z, I use the green scrubbies with yellow sponge attached but guessing the green part may be the same shown, just not sure. I grab them at the grocery or Home Depot.



OK, that's what I thought...just removing all doubt


----------



## Geo87

Sorry coming into this rather late. 
"garage tinkerer" and pro cook here. 
There are A lot of comments in this thread that would lead people to believe thinning is something complicated that should be left to people who know what they are doing. 
That's just going to put people off from learning! 

I learnt the most about geometry, thinning and asymmetry from just having a go without worrying about screwing up. If you "screw up" get some sandpaper  or learn from the mistake you made and correct it. 

Yes I know what cross sectional geometry is, yes I can thin from the spine down if it needs it and yes your damn right I can make most knives cut better than how they come OOTB . Yes they were made by someone that knows more than me but as stated a lot of knives come with very conservative geometry and need some work to Get them cutting good. A lot of knives come with steering and wedging issues and cut like pigs. But what would I know, leave it to the pros right? 
Things get overcomplicated too often.

I just tried a gyuto from Mert that cuts just as well if not better than any high end knife I have tried. He would have been considered a "garage tinkerer" not so long ago I'm glad he wasn't put off by stuff like this


----------



## panda

yes, don't nerd the issue and just try it for yourselves, with grind altering you really can only learn by trial and error. with enough experience (and patience as it will take many sessions) you can even turn a cheap dexter into a formidable cutter.


----------



## chiffonodd

I'm sympathetic to the pros who have to field tons of questions and correct misinformation for a bunch of "garage tinkerers" with time on their hands and access to google - kinda like doctors dealing with patients who think they've already self-diagnosed everything on WebMD. But I also hope that it enriches everyone's experience to have enthusiastic participants in this field, and hey it has to be good for business 

Bottom line, this stuff is fun and I'm sure everyone has great respect for the knowledge and skill of the people that have made it their life's work.

Now off to tinker . . .


----------



## Mucho Bocho

Geo87 said:


> Sorry coming into this rather late.
> "garage tinkerer" and pro cook here.
> There are A lot of comments in this thread that would lead people to believe thinning is something complicated that should be left to people who know what they are doing.
> That's just going to put people off from learning!
> 
> I learnt the most about geometry, thinning and asymmetry from just having a go without worrying about screwing up. If you "screw up" get some sandpaper  or learn from the mistake you made and correct it.
> 
> Yes I know what cross sectional geometry is, yes I can thin from the spine down if it needs it and yes your damn right I can make most knives cut better than how they come OOTB .
> 
> Things get overcomplicated too often.



Well said Geo. this has been my experience too. Just ask my Tadafusa Nashiji petty.


----------



## Benuser

It isn't all that complicated. First get the notion that sharpening is not about putting an edge on the end of piece of steel. That's for EdgePRO victims. Sharpening is about moving a previous configuration towards the spine. The entire configuration. Now, as nobody will start every sharpening session at 1/2" behind the edge, so some periodic heavy maintenance -- thinning -- becomes necessary. Don't wait too long, and have the original configuration in mind.


----------



## Keith Sinclair

Guess I came across one sided. It is because I see so much knife abuse mostly from general public, but also from cooks in the field. I used ultra thin blades at work, bevels close to the stone. Never let the edges touch hard objects.

It is common sense that you don't split chickens down the spine, half lobsters, I would even draw the line at Kabocha Pumpkin with a laser. Also when you are taking a lot of steel off an expensive gyuto you cannot put it back & they will wear down faster because less steel on the blade.

I like the geometry of the Ginga SS Gyuto. Respect the assem. grind, thin a little behind the edge 3-5%, put on a micro bevel. One of the better stainless knives I have used cuts quite well. Jon's thinning job looks great sure it falls through food. Would not advise ginga owners to take a already good blade put it on a belt, diamond plate, coarse stone to remove more metal. JMHO

I have mileage on my Spa Hiromoto both with use & as a pass around knife at school. The thinning job Dave did is excellent it does cut better than stock. I give strict instructions, no hard objects, just fruits, vegetables. Meat with out bone. It gives them a chance to learn knife care & cut with a fine blade.

So thin all you like, I am considering thinning my SRS-15 blade. Just saying you can buy already thin knives. Certainly this group has many capable of thinning down their blades.


----------



## wphill

:viking::running::spin chair::beatinghead::hula::relax:eace:


----------



## krx927

Good to see that I sparked nice discussion about the topic!

I must say that I completely agree with all the comments saying that us garage tinkerers should just go ahead and try things out. This is my attitude and this is what I am doing. The results might not be perfect the first time (just like my first picture of the thread where I obviously still have quite some more thinning to do) but eventually we will get the knowledge and experience... 

I just have one more question for Jon: 2 times in this thread you were referring to knives thinned by amateurs as axes. Are you referring to the fact that they are still thick like axes or that they completely destroyed convex grind and made it completely flat?


----------



## XooMG

krx927 said:


> Good to see that I sparked nice discussion about the topic!
> 
> I must say that I completely agree with all the comments saying that us garage tinkerers should just go ahead and try things out. This is my attitude and this is what I am doing. The results might not be perfect the first time (just like my first picture of the thread where I obviously still have quite some more thinning to do) but eventually we will get the knowledge and experience...
> 
> I just have one more question for Jon: 2 times in this thread you were referring to knives thinned by amateurs as axes. Are you referring to the fact that they are still thick like axes or that they completely destroyed convex grind and made it completely flat?


Not Jon but what I think he meant was that the thinning of a Piggyfusa or a Chunkabocho (not sorry) only gets addressed within a few millimeters of the edge, leaving a thick blade with a small radius convexing near the edge. For ultrathins, something like this might not be a totally inappropriate treatment (could improve entry separation), but for a fat edge, it won't be adequate.


----------



## rico

I'm sure this has been asked and answered before, but I need to know (asap) what is a good stone grit for thinning behind the edge? I've got a 400 grit stone, but I'm wondering if I should go to a 220 or 180 grit ???

Thanks in advance !!


----------



## rico

Nevermind . . . found the answer. Ordered a ******** Bamboo 180 Grit


----------



## JBroida

krx927 said:


> Good to see that I sparked nice discussion about the topic!
> 
> I must say that I completely agree with all the comments saying that us garage tinkerers should just go ahead and try things out. This is my attitude and this is what I am doing. The results might not be perfect the first time (just like my first picture of the thread where I obviously still have quite some more thinning to do) but eventually we will get the knowledge and experience...
> 
> I just have one more question for Jon: 2 times in this thread you were referring to knives thinned by amateurs as axes. Are you referring to the fact that they are still thick like axes or that they completely destroyed convex grind and made it completely flat?



thick like axes


----------



## rico

rico said:


> Nevermind . . . found the answer. Ordered a ******** Bamboo 180 Grit



OMG, 180 grit took forever to thin!! . . . 60 grit on order


----------



## chinacats

rico said:


> OMG, 180 grit took forever to thin!! . . . 60 grit on order



Stop! No reason to use a 60 grit on a knife, perhaps you should look at an Atoma plate?


----------



## Benuser

I use P120 automotive sandpaper with linen backing. JIS60 sounds horrible to me. Why so fast and so dirty?


----------



## XooMG

If you need to do that much work, a fixed stone might not be the right tool for the job in the first place.


----------



## panda

60 grit would come in handy opening up house knives.


----------



## Benuser

Rico, for what kind of steel would you need a JIS60 stone, where a 180 does fail??


----------



## Geo87

60 grit???? Sounds like you need a belt sander not a stone


----------



## rico

XooMG said:


> If you need to do that much work, a fixed stone might not be the right tool for the job in the first place.



Well, probably you're right about that. I was slaving away all weekend with the 180 grit stone thinning a 240mm gyuto all the way down a burr on the opposite edge. Needless to say, the knife is now very thin behind the edge and it has a nice, "infinity", tapered feel to it. I'll put a 15* angle on the edge. I was thinking a 60 grit stone would do the job a lot quicker. Not as fast as a belt sander of course, but I'm not going to be thinning enough knives to warrant having a belt sander. Any suggestions would be welcome !


----------



## Benuser

Still wondering what kind of steel?


----------



## chinacats

Pics?


----------



## rico

Benuser said:


> Still wondering what kind of steel?



AEB-L Swedish Damascas HRC 59-60


----------



## chinacats

Perhaps your stone was loaded...did it feel slick when you were using it?


----------



## rico

Here are some pics. Still have to polish and sharpen.

photos didn't post, maybe later . . .


----------



## rico

chinacats said:


> Perhaps your stone was loaded...did it feel slick when you were using it?



Ha! It did feel slick at times and seemed to bite at other times. Required a lot of water and flattening the stone. With a fresh slurry it seemed to cut faster . . . 

I guess it was a crazy project. I wouldn't want to go through that again ! But the taper feels so sweet !


----------



## rico

I found myself in a 3 hour prep battle late yesterday and that ultra thin blade ^ came through like a champ. I hadn't even got around to putting a final edge on it !!!


----------



## rico

Geo87 said:


> 60 grit???? Sounds like you need a belt sander not a stone



Ummm . . . upon further analysis I think you're right. Any recommendations for a belt sander?


----------



## ThEoRy

harbour freight 1x30 for $30


----------



## Mrmnms

ThEoRy said:


> harbour freight 1x30 for $30



+1


----------



## rico

OK OK . . . I'll check it out. thanks,

I'll hold off on the JET 2x48 for $300 . . . lol . . .


----------



## rick alen

"harbour freight 1x30 for $30 "

And if it throws one of its crap bearings on you ebay should have them cheap enough, not sure but I think you can get at them. For the hobbyist often times HF power stuff will run long enough to get your money's worth. Don't buy their power washer though.


Rick


----------



## nepastovus

interesting thread. nice to see some pictures of what people are using and they prefer. more please!

This is thinned down knife by Takeda






and this is my daily preference in pro kitche


----------



## wphill

The bottom picture...same as the above takeda? FWIw...the "behind the edge " looks less promising from the second one. 
Personally, just when I think that I have a killer edge, I pick up one OTB and...shezzz...it's better than the one I so
diligently worked on. In this case...ysuke sakai 240 gyuto mono white steel is the one OTB. SS clad is starting to look like trouble to me.
Hard to rely on such a generalization...just say'n. No matter, nice to have pictures.


----------



## Benuser

Not willing to speak for nepastovus, it's a another knife, with another geometry, more suited to daily pro life, where the first one would hardly survive. By the way, be aware that a lot of blades are thicker at the heel, and in the second picture the apparent thickness is enhanced by the rounding of the heel. With that geometry and clad pattern, is it a Hiromoto?


----------



## Livlif

Benuser said:


> Not willing to speak for nepastovus, it's a another knife, with another geometry, more suited to daily pro life, where the first one would hardly survive. By the way, be aware that a lot of blades are thicker at the heel, and in the second picture the apparent thickness is enhanced by the rounding of the heel. With that geometry and clad pattern, is it a Hiromoto?



Why wouldn't the Takeda survive pro use?


----------



## panda

It would chip, and retention would suffer.


----------



## Livlif

panda said:


> It would chip, and retention would suffer.





Because it's too thin? I thought I'd wads high Rockwell hardness in AS. Shouldn't that give the best edge retention possible?


----------



## XooMG

Livlif said:


> Because it's too thin? I thought I'd wads high Rockwell hardness in AS. Shouldn't that give the best edge retention possible?


High hardness with good edge stability will prevent the edge from rolling and deforming much in a plastic manner, but it will not prevent fractures that lead to chips.


----------



## XooMG

For knives with very very thin blades, I prefer a tiny bit of meat immediately behind the edge:





(knife is Carter Muteki, thinned)

For thicker knives, I like having a pretty thin edge, as it is still pretty stable:




(knife is a Sakai Takayuki Shoshin Sakura, out of the box)

In both cases, I'm just a home user and don't beat up my edges at all.


----------



## Kippington

Haha there's so much going on in that last picture (grind angles/grits/layers) its like a picture of the Burj Khalifa!






But in all seriousness.. those are some very nice looking grinds you have there!


----------



## rico

+ 1


----------



## nepastovus

the first picture is Takeda classic gyutoh which had bad OOT bevels, no root veg could have been cut without tearing. the second picture is Fujiwara Teruyasu Nashiji, which looks way too thick but actually cuts way better than it looks. 
and yes, Takeda that thin chips very easily and doesn't get used near as much as another


----------



## labor of love

nepastovus said:


> the first picture is Takeda classic gyutoh which had bad OOT bevels, no root veg could have been cut without tearing. the second picture is Fujiwara Teruyasu Nashiji, which looks way too thick but actually cuts way better than it looks.
> and yes, Takeda that thin chips very easily and doesn't get used near as much as another



Nice job on that Takeda.


----------



## mhpr262

Would anybody be willing to show how thinning is done properly on European/German knives that don't have a convex bladeface? I usually thin mine by putting the whole bladeface on the flat, supported part of my belt sander, but press down only on the part closest behind the edge. The part of the bladeface closest to the edge barely rests on the belt. So far the results (on three $10 stainless knives) have been quite good. grinding only on the flat supported part tends to leave a slightly uneven finish though, so I usually finish on the "slack" unsupported part (that is still under pretty high tension though) which leaves a very slightly convex bladeface.

would that be considerered proper technique by the pros out there?


----------



## mhpr262

> The part of the bladeface closest to the edge barely rests on the belt



Sorry, of course I meant


> The part of the bladeface closest to the *SPINE* barely rests on the belt


----------



## rick alen

You can take the thinning right to the spine and beyond, especially at the tip where a distill taper of 3"+ to a <.02" tip is highly desirable (except maybe in a rough pro kitchen where closer to .04" at the tip would be safer).

Taking a knife like the Vic rosewood, with completely flat sides and an already decently thin edge (.015"/.38mm), just .003 of convexing/per side [to bring the edge to .009"] makes a noticeable difference in food release. Not dramatic mind you, just noticeable. So in the case of flat sided knives, especially if you are going to be cutting potatoes, certainly take advantage of some or all of the convexing you can, on both sides.


Rick


----------



## mhpr262

So convex is actually helpful? That's good to know. I keep being surprised how much the knives are improved, and how mostly decent they look after having done the work, despite my being mediocre at best with my hands. Next in line are three F. Dick ProDynamic industrial kitchen workhorse knives that have a genuine "battle axe" geometry. I swear the bevel is 2mm wide .... in some places ...

I use a cheap a$$ $90 fixed speed stationary belt sander and a felt buffing wheel and it does have its limitations, but good belt sanders are $$$$$$ ....


----------



## Ruso

Little thinning on Hiromoto AS, before and after


----------



## Benuser

That's for sure no little thinning. Good work. I prefer proceeding by little steps and verify for steering and food release.


----------



## rick alen

Benuser said:


> That's for sure no little thinning. Good work. I prefer proceeding by little steps and verify for steering and food release.



Here I think it would be a good idea to use a jig to set in the bevel leading to the edge. A while ago I did some solid modeling of cross-section edge profiles and it seemed to me as I recall that 2deg/side was about right for a middle of the road gyuto, a laser would be 1.5deg or maybe less, and a wide-bevel gyuto as much as 3deg, probably not more. Looking at the Geshin Heiji, that got mention in the recent wide-bevel gyuto thread as an extreme example, it does appear to have about a 3deg lead in from the photo on the JKI site.


Rick


----------



## Prize78

How much does thinning affect the 'finish' of the edge? As surely, you have to 'scratch' the metal in order to remove some? I'm not confident in doing mine incase I scratch it up and it looks terrible?!


----------



## XooMG

Prize78 said:


> How much does thinning affect the 'finish' of the edge? As surely, you have to 'scratch' the metal in order to remove some? I'm not confident in doing mine incase I scratch it up and it looks terrible?!


I'd bet that aside from major thinning work that requires massive amount of material removal, the biggest issue holding folks back from thinning their knives is messing up the finish. For less extreme thinning jobs, people will generally tell you most of the work is in refinishing.


----------



## malexthekid

XooMG said:


> I'd bet that aside from major thinning work that requires massive amount of material removal, the biggest issue holding folks back from thinning their knives is messing up the finish. For less extreme thinning jobs, people will generally tell you most of the work is in refinishing.



I think you hit the nail on the head. It is the reason I have not done any progressive thinning on my knives.


----------



## rick alen

C'mon, really? Seriously???? Are we talking about Safe Queens here or real working knives?


Rick


----------



## Timthebeaver

Agree, why anyone would ruin the geometry and compromise the performance of their knives for the sake of some scratches is beyond me - they are tools.


----------



## Geo87

Sandpaper... Problem solved.
Unless you have a clad knife and care About the contrast. Then you need stones that will bring out that contrast. There's really enough information on these forums for anyone to have a crack at thinning and get pretty good results


----------



## Chuckles

Not all thinning jobs need to be extreme. If you keep consistent angles there is no reason that you would need anything but stones to restore your finish. Here you see the hazy King 800 finish is where the 'major' part of the thinning occurred. The mirrorish finish toward the edge is still mostly above the cutting edge. Just that much above the edge would still be thinning and could help a knife quite a bit by 'knocking off the shoulders'. Setting up a convex knife like this with a faux shinogi and then a smaller thinning angle helps you know where the maitenance thinning should take place and where the big work is when the time comes. I don't think thinning has to be a scary major project everytime but it does need to be done on the small scale periodically to keep the knife performing.


----------



## rico

XooMG said:


> I'd bet that aside from major thinning work that requires massive amount of material removal, the biggest issue holding folks back from thinning their knives is messing up the finish. For less extreme thinning jobs, people will generally tell you most of the work is in refinishing.



I just thinned a Damascus AEB-L and I need to go back and polish to bring out the Damascus finish. The improved performance is well worth a few weeks of dull finish. What should give people pause is doing a crummy job of thinning of a good grind on an expensive knife !!! imho . . :O


----------



## malexthekid

This is sort of what has my hesitant to thin my knives.

The ones that I think I would do (or at least have some work to do to them that would then require thinning) are damascus. And I am hesitant to then having to re-etch them aftewards.

Maybe I should just bite the bullet and do it.


----------



## gregg

rick alen said:


> Your Akifusa is a bone-splitter at the moment. A $20 pair of verniers will tell you just how thick you are. .015"/.38mm is still thick enough for a work horse, I prefer >.010" for 99% of what I do.
> 
> Speaking of thinning cheap knives, I thinned some very soft stainless to about .008" and the other day I was cutting around some ribs with it, I didn't think I made much contact with bone but there appeared 2 sizeable dimples bent into the edge.
> 
> 
> Rick


Just a quick question; where exactly on the edge are you getting the .38mm, (or .25mm) thickness from? eg., just behind the primary bevel, or higher up?


----------



## bkdc

Do the experts have any advice on doing some major thinning on a san-mai knife where the outer cladding is a VERY soft stainless steel? It is sooooo labor intensive as the metal does not want to abrade off no matter what stone or diamond plate I use.


----------



## JBroida

what knife?


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## bkdc

It's a Teruyasu Fujiwara Nashijii. I took it as my project knife and completely reground it on nothing but whetstones all the way up to the spine. It cuts well now, but wow.. I don't know how much total time was put into it. The cladding was soooo slow to work off even on the lowest grit stones or atoma plates. It was just so soft!


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## JBroida

bkdc said:


> It's a Teruyasu Fujiwara Nashijii. I took it as my project knife and completely reground it on nothing but whetstones all the way up to the spine. It cuts well now, but wow.. I don't know how much total time was put into it. The cladding was soooo slow to work off even on the lowest grit stones or atoma plates. It was just so soft!



yeah.. they are time consuming. I use my big wheel to thin, then refinish on the belt grinder and buffer. By hand, they take forever. Better than the diamond, the 220 grit stones work wonders on these kinds of steel.


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## rick alen

gregg said:


> Just a quick question; where exactly on the edge are you getting the .38mm, (or .25mm) thickness from? eg., just behind the primary bevel, or higher up?



Just behind the primary. And the other point should have indicated <(less than) 0.010".


Rick


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## CaremeFraiche

Regarding Japanese knives, does anyone thin their knives in Japan?


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## chinacats

CaremeFraiche said:


> Regarding Japanese knives, does anyone thin their knives in Japan?



Only the people that like for the knife to cut well...


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## Lizzardborn

CaremeFraiche said:


> Regarding Japanese knives, does anyone thin their knives in Japan?



If you look at Jon's videos the thinning is built in into single bevel knives sharpening. You move the shinogi line up a bit, then sharpen the secondary bevel to the edge, then blend together the two. 

So you are just removing the fatigued steel and moving the whole configuration up.


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## mark76

JBroida said:


> yeah.. they are time consuming. I use my big wheel to thin, then refinish on the belt grinder and buffer. By hand, they take forever. Better than the diamond, the 220 grit stones work wonders on these kinds of steel.



Jon, if you ever want to do a video again... I'm considering to get a (cheap) wheel which I'll primarily use for thinning. But I have no idea to properly use a wheel for regrinding...


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## CaremeFraiche

I can't help but think that reading through these posts that almost all knives need some kind of thinning and that Japanese knives in general are inadequate unless they have been ordered to the specifications of a particular vendor. There has to be some level of objectivity in these discussions. There a lot of opinions and commentary that seem to be self serving.


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## rick alen

CaremeFraiche said:


> I can't help but think that reading through these posts that almost all knives need some kind of thinning and that Japanese knives in general are inadequate unless they have been ordered to the specifications of a particular vendor. There has to be some level of objectivity in these discussions. There a lot of opinions and commentary that seem to be self serving.



Not necessarily so about the suppliers and vendors, but yes, all knives need thinning, eventually. Self serving/lack of objectivity????

You have everything from lasers to work horses. Often people thin a knife because they decide they want something more like a laser. But any knife that gets sharpened is eventually going to need thinning, regardless. Its a simple fact of geometry. As you sharpen the primary bevel moves up and given that the secondary bevel is some kind of angle this means the thickness behind the primary bevel I going to get thicker.


Rick


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## AllanP

rick alen said:


> Not necessarily so about the suppliers and vendors, but yes, all knives need thinning, eventually. Self serving/lack of objectivity????
> 
> You have everything from lasers to work horses. Often people thin a knife because they decide they want something more like a laser. But any knife that gets sharpened is eventually going to need thinning, regardless. Its a simple fact of geometry. As you sharpen the primary bevel moves up and given that the secondary bevel is some kind of angle this means the thickness behind the primary bevel I going to get thicker.
> 
> 
> Rick



the idea of thinning scares the hell out of me. I want to strop as much as possible to not wear away as much steel in each session

it seems like even with the right equipment it's very labour intensive and I still probably would mess up somehow and send it someone to fix it


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## mhpr262

AllanP said:


> the idea of thinning scares the hell out of me. I want to strop as much as possible to not wear away as much steel in each session



Just practice with some cheap, industrial stainless knives beforehand. I have by now thinned a few of those on my belt sander and the results were quite impressive. It makes a huge difference in how the blade glides through the food. I now have a few 10-15 dollar knives that cut like knives ten times their price.

It helped with my nervousness about thinning, too. I'm not quite ready to take on thinning some $500 knife yet, though, but I keep practicing ... :biggrin:


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## Benuser

AllanP said:


> the idea of thinning scares the hell out of me. I want to strop as much as possible to not wear away as much steel in each session
> 
> it seems like even with the right equipment it's very labour intensive and I still probably would mess up somehow and send it someone to fix it



You will end with a lot of fatigued steel that won't hold any edge.


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## mhpr262

Lizzardborn said:


> If you look at Jon's videos the thinning is built in into single bevel knives sharpening. You move the shinogi line up a bit, then sharpen the secondary bevel to the edge, then blend together the two.
> 
> So you are just removing the fatigued steel and moving the whole configuration up.



Thinning a Euro style knife with completely flat bladefaces and an (ideally) very small cutting bevel is a very different sort of undertaking though. I wish Jon would make a video on that ...


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## Benuser

Lizzardborn said:


> So you are just removing the fatigued steel and moving the whole configuration up.


Very well put indeed.


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## _PixelNinja

AllanP said:


> the idea of thinning scares the hell out of me. I want to strop as much as possible to not wear away as much steel in each session
> 
> it seems like even with the right equipment it's very labour intensive and I still probably would mess up somehow and send it someone to fix it


It scared me too at first (I am OCD about messing things up) but I took a deep breath and just went for it since it is a necessary part of knife maintenance. As long as you are observant and understand what is going on, it should not be that difficult to get good results. I find the hard and most time consuming part to be refinishing the blade rather than the actual thinning. 

In regards to stropping, I agree withBenuser  you don't want to over do that.


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## rico

I measured the angle of the bevel on some of my knives. It ranges from 1.7 - 1.8 degrees to 3.8 - 4.0 degrees. The higher angle knives are kind of expensive and known to be quit thin behind the edge and they do cut like a dream. My conclusion is to find a way to thin at about a 3.8 degree angle. I'm thinking of a belt / disc sander combo that could be used to grind a jig with the disc at the correct angel and then use the jig to hold the knife at the proper angel against the belt. Another advantage of this method would be to retain more of the original surface finish, such as damascus or pear skin for example. Any thoughts?


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## turbochef422

At first thinning was a scary thought with a lot of trial and error all I can say is don't over think it. I wouldn't worry about exact angles going by feel is the way to go. Now I thin somewhat every time I sharpen. I start just above where the bevel starts and work my way down to the edge. Going alittle higher each time I sharpen.


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## Keith Sinclair

turbochef422 said:


> At first thinning was a scary thought with a lot of trial and error all I can say is don't over think it. I wouldn't worry about exact angles going by feel is the way to go. Now I thin somewhat every time I sharpen. I start just above where the bevel starts and work my way down to the edge. Going alittle higher each time I sharpen.



Exactly:thumbsup: Thinning a little behind the edge keeps a knife cutting well. The thinning sets you up for your final bevel.


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## Benuser

Have your stone flat, and keep the relief bevel as low as you can.


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## Keith Sinclair

Akifusa SRS-15 took a fair amount of steel off lower blade face. Enough for me anyway
Sanded to 320 kind of satin finish needs some more work. Dropped the heel on handle like JMO think it improves the lines always liked Randy Hass handles.


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## spoiledbroth

Nice work!! Love what you did with the butt of the handle. :thumbsup:


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## krx927

keithsaltydog said:


> Akifusa SRS-15 took a fair amount of steel off lower blade face. Enough for me anyway
> Sanded to 320 kind of satin finish needs some more work. Dropped the heel on handle like JMO think it improves the lines always liked Randy Hass handles.




Can you make another pics of the coil with the ruler like in my first post to be able to compare it directly?
Thanks!


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