# Quick note on thinning for people new to it ( faster )



## branwell (Feb 3, 2021)

I see a fair few questions in various threads about thinning and though I'd add this.

This is for those of you that have a will to thin but haven't done it before and don't have the equipment.

You might be tempted to have a go at it with your 1K or 500 grit stones. My advice: don't. You will end up till the wee hours with bloody fingers and worn out stones.

Here's the reality of thinning. You know how long it takes to re bevel a knife and get it to a nice edge? Now look at your bevel. Few hairs wide right. Now look at the secondary bevel. Orders of magnitude bigger. Not only that, unless your knife is already super thin and doesn't really need thinning, you are going to have to remove a significant amount of material. 

So, your plan is to use the same stones you sharpen on to thin your blade. This is not a good plan. But you are thinking "I don't know if I want to spend the money on good thinning stones. I just want to try it."

Fine. Not claiming this is a perfect plan, but you could do worse.

Get a block of wood 1" sq x 6 to 8 inches long. 
Get some 80 / 120 / 220 / 320 grit closed grit wet and dry sand paper ( Rhynowet etc ). 
Painters tape the blade above where you want to thin ( to help prevent scratches should you get distracted ).
Lay your blade flat length wise on your sink bridge and have at it with for and aft strokes with the stick 90 degrees to the knife. 
Pro tip : Alternate your stroke path a few degrees with each grit to insure you get the previous grits scratch pattern out.

This does several things. 

It allows you to see what you are doing. Big ups for seeing what you are doing. 
It allows you to use two hands to adjust pressure on the stick.
It allows you to use a lot of pressure.
The low grit will get the job done fast. ( Unless your knife is a proverbial machete, this should take 15 to 30 minutes tops, as opposed to literally hours on a 1K stone )

Once you are done with the paper, move to the stones to finish the job.

You might be thinking. But don't the "pros" use stones. Ha. No. Not for grinding. In Japan many use water wheels. In the US, most use water cooled belts and both transition to stones to finish assuming a stone finish is what the knife calls for.

All that said. If you really want to do the heavy lifting on stones, I'll tell you even a 150 grit will take you long enough to binge half a season of Letter Kenny.

I'd suggest something along the lines of 60 / 150 / 220 / 400 / 800 etc.

Good luck. May the Kasumi be with you.


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## JBroida (Feb 3, 2021)

god i hope no one ever tries to thin on a 1k stone... that would suck. You're right that most pros use powered equipment... i use a waterwheel for sure. But when I don't, I'm using a 220 stone for this kind of thing. Its pretty fast all considering.


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## big_adventure (Feb 3, 2021)

JBroida said:


> god i hope no one ever tries to thin on a 1k stone... that would suck. You're right that most pros use powered equipment... i use a waterwheel for sure. But when I don't, I'm using a 220 stone for this kind of thing. Its pretty fast all considering.



Hahahahaha - I did this today.  More than 300 hard strokes on each side to flatten a hollow grind on a pretty new Moritaka Nakiri.


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## rmrf (Feb 3, 2021)

JBroida said:


> god i hope no one ever tries to thin on a 1k stone... that would suck. You're right that most pros use powered equipment... i use a waterwheel for sure. But when I don't, I'm using a 220 stone for this kind of thing. Its pretty fast all considering.



Well this would explain why my last attempt at thinning seemed ineffective...


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## big_adventure (Feb 3, 2021)

rmrf said:


> Well this would explain why my last attempt at thinning seemed ineffective...


Honestly, I wouldn't have realized how ineffective it was without the sharpie. That made it crystal clear.


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## ModRQC (Feb 3, 2021)

Sanding on a blade’s path is slower than using a low grit stone. Been there. Thinning is nowhere near taking more than 30 mins to perhaps 1 hour - that for a western thick blade/hard monosteel that I can promise you going down at it with sandpaper fixed to mellow hard backing will take hours.

Some use sandpaper like a stone and I can agree with that. Fact is coarse stones/sandpaper work faster with more pressure, and you can never level off as much pressure using a sanding device down on a narrow path of blade trying to give a consistent scratch pattern than pushing the blade down on the coarse medium. Also knife will likely wobble when closing to the tip or generally move if you start using force on it as it lays flat. Handle will get in the wat for the knife to lay flat. Pros may have a bench with nails to fix the blade onto so it won’t move, and do that without handles on.

Trick above will work well for giving some migaki polish as to erase the scratches from the coarse stone. Then again, faster to transition to coarse-med and meds to lighten up the scratches, making final sandpaper run easier and shorter. And when you’re there, you may want to start practice towards fine stone kasumi.

My take... to each his own.


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## spaceconvoy (Feb 3, 2021)

ModRQC said:


> Sanding on a blade’s path is slower than using a low grit stone. Been there. Thinning is nowhere near taking more than 30 mins to perhaps 1 hour - that for a western thick blade/hard monosteel that I can promise you going down at it with sandpaper fixed to mellow hard backing will take hours.


That is the opposite of my experience. I wonder what brand you're using, and if you're working the same worn piece of sandpaper for hours.

I agree with you that a coarse stone will take the better part of an hour, but for me that's much too slow. With good quality sandpaper (Rhynowet or 3M Pro) it should be more like 10-15 min.

Also wondering if you're trying to use it wet. Just because it's "wet or dry" doesn't mean it should be used like a water stone. In my experience the fastest way to remove metal without power tools is high quality sandpaper worked dry (wear a dust mask)


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## Bodine (Feb 3, 2021)

I'm sorry but 80 grit on a knife, I can not do that, I'll take the extra time.
But I do not thin often.


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## spaceconvoy (Feb 3, 2021)

Bodine said:


> I'm sorry but 80 grit on a knife, I can not do that, I'll take the extra time.
> But I do not thin often.


Yeah that's only for reprofiling and drastic thinning on project knives, not for good knives. Fwiw, removing 80 grit sandpaper scratches is much easier than scratches from the SP120


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## TB_London (Feb 3, 2021)

Thinning on stones is a good way to learn angle control and get a feel for the stone. Someone new to freehand sharpening will probably benefit from the experience. After that, coarse stone or sandpaper. 60 grit works fast but introduces deep scratches. I go 60, 120, 240 and then 400 or to a stone.


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## ModRQC (Feb 3, 2021)

spaceconvoy said:


> That is the opposite of my experience. I wonder what brand you're using, and if you're working the same worn piece of sandpaper for hours.
> 
> I agree with you that a coarse stone will take the better part of an hour, but for me that's much too slow. With good quality sandpaper (Rhynowet or 3M Pro) it should be more like 10-15 min.
> 
> ...


 
I think you are one to use it as you’d do a stone? Read my whole post vs the OP intro, would you?


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## ModRQC (Feb 3, 2021)

Also comparing 80 grits sandpaper to my coarsest stone Sigma 240... also dust management. Also no mud helping/polishing effects. But still I agree: it should be goddamn fast using 80 grits dry sandpaper fixed to hard backing in a stone format. My answer was concerning the OP. In the end of the day I will always choose a stone for total control. I don’t have to switch grits or change a worn out sheet: stone rehabs itself as you go when used correctly. If I want faster I can buy lower grit stones still. Me doing all of my work in my kitchen also prevents using sandpaper aggressively - it can’t be managed well enough.


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## ian (Feb 3, 2021)

I think this thread is a little limited in its definition of thinning. There is absolutely thinning that you can do on a 500 grit stone. I would not do substantial thinning or grind alterations on a stone of that grit, but my (second hand) Dalman came a bit thick behind the edge and I got it to where I want it with 15 min total on Chosera 400/800. I feel like most people talking about thinning here are talking about usual maintenance thinning, not the kind of thinning you’d send your knife to @JBroida for. So, in general I agree coarser is better, and for heavy work I’m all about the sandpaper, but let’s just acknowledge that a lot of the thinning people do around here won’t benefit from starting at 60 grit.


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## Twotimehojo (Feb 3, 2021)

@jon. So in your video on thinning what grit stone were you using? I do not think that was mentioned. 




JBroida said:


> god i hope no one ever tries to thin on a 1k stone... that would suck. You're right that most pros use powered equipment... i use a waterwheel for sure. But when I don't, I'm using a 220 stone for this kind of thing. Its pretty fast all considering.


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## ian (Feb 3, 2021)

Also, fwiw I personally would find it harder to be accurate in where I was taking off metal using the sandpaper wrapped around a piece of wood method above. Maybe I just haven’t practiced at that. It’s kinda nice being able to place your finger pressure exactly where you want the metal to come off, though. And for extreme metal removal, I’ll just use a belt. Nice to hear about your method. Sounds like it works well.


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## Luftmensch (Feb 4, 2021)

ian said:


> I think this thread is a little limited in its definition of thinning. There is absolutely thinning that you can do on a 500 grit stone. I would not do substantial thinning or grind alterations on a stone of that grit, but my Dalman came a bit thick behind the edge and I got it to where I want it with 15 min total on Chosera 400/800. I feel like most people talking about thinning here are talking about usual maintenance thinning, not the kind of thinning you’d send your knife to @JBroida for.



Agreed! Definitions are important.

Thinning can be an integral process of sharpening and even done at 1K. Just to be clear on terminology (primary/secondary bevel), I will use the definitions in this diagram (ignore the fact that it is for single bevels):





[wish I could credit the image, it is awesome... but I don't know the original source]


To *me*, working on the primary bevel is _thinning_. It does not form the apex of the cutting edge - that is the job of the secondary bevel. The more material you remove from the primary bevel, the less steel you have behind the secondary secondary bevel. If you remove enough, you will achieve a zero-edge and raise a burr (no secondary bevel).

For simplicity, lets call working on the secondary bevel _sharpening_. If you only ever work at the secondary bevel angle, the amount of steel behind the apex will get wider and wider. You can choose to 'thin' that material by working on the primary bevel every time you sharpen... every other time you sharpen... or once every three years. The longer you wait, the more material you will need to remove to reduce the amount of material behind the edge and the size of the secondary bevel - the bigger a job it becomes, perhaps belt sander or water wheel territory.

I drafted this diagram to show the cross-sectional geometry:






Ideally you want to keep the angle behind the edge, and the width behind the edge, the smallest they can be before edge damage becomes a problem. Routine thinning helps maintain a smaller width behind the edge. If you keep a small secondary bevel, I will contend you can indeed thin at 1K grit.

I think a reason people might not thin their knives is that for many knives it will cause unavoidable aesthetic damage. This is particularly true for knives that have no clear delineation between the primary bevel and the blade flat. So either you choose to only work on the secondary bevel, accept worse aesthetics or go through the bother required to restore the finish of the knife.

Sending a knife off to a specialist with a belt sander or water wheel might indicate a lack of long term maintenance or a desire to _regrind_ the knife. You might want to regrind the knife if you think the primary bevel is too obtuse and you want lower it so the knife is not as much of a wedge. But I am not so sure changing the grind profile should be considered 'thinning'...


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## JaVa (Feb 4, 2021)

I'm wondering what is everyone doing with their knives that there's so much need for thinning?

Don't get me wrong it's VERY important, but not before it's relevant. If a sharp knife doesn't cut well, then thinning is required. We might be giving the appearance to guys new to KKF that all knives should be thinned all the time.

Sure some knives need help when new and some grinds need to be maintained regularly to keep them at peak performance. BUT...

Most of my knives are so thin behind the edge that you couldn't thin them if you wanted to. My Wakui hairline, Tanaka ginsan and migaki, Shiro Kamo migaki, Takamura migaki R2 etc. There is just no metal behind the edge to thin and that thinness goes so high up the grind that I will have years before they need to be addressed.

I'm a chef and work in a pro kitchen. With my rotation my knives get sharpened every two to four weeks and after several years, none of them are even close to need to be thinned.

Our go to knife at home is Tanaka VG10 dammy 190. It's thin right behind the edge, but the convex grind gets thicker early, after 3 years of everyday home use is far from needing a thinning.

My Mac Pro 240 gyuto had to be thinned, but that's after about 10 years of use. My Mac petty too. My Kohetsu Hap40 needed thinning right out the box because of the horrendous grind and edge profile. Out of my 30 or so knives those are the only ones that I've needed to thin.

If you use only one or two knives daily and sharpen them several times a week. I can understand the need to thin them regularly, but most of us use several knives. So why all these knives need all this thinning?

Asking for a friend!


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## big_adventure (Feb 4, 2021)

JaVa said:


> I'm wondering what is everyone doing with their knives that there's so much need for thinnig?
> 
> Don't get me wrong it's VERY important, but not before it's relevant. If a sharp knife doesn't cut well, then thinning is required. We might be giving the appearance to guys new to KKF that all knives should be thinned all the time.
> 
> ...



I like to say to people that nobody is "right" in this kind of discussion. The corollary is that the only person "right" in your kitchen is you. 

Some knives "need" (read: would be optimized, for a certain user) thinning out of the box. Some don't. Some, hell, COULDN'T. I've got a Kurosaki bunka that would be "impossible" to thin: you can almost see through the blade as it is.

I think the thinning idea comes from the idea that, if you want to maintain a consistent geometry over the life of the blade, you should probably thin it some small amount every time you sharpen, more or less. This makes sense: the blade isn't two parallel sides, it's a complex v-ish shape from the spine to the cutting edge. If you remove steel on the cutting edge, you will increase the angle of that "V" over time, which might (or will) change the cutting performance of the knife. Do you NEED to thin? C'mon, man! Of course you don't. It's your knife, you paid for it, you can use it exactly how you want to! If it's fine without thinning, don't thin! If you choose not to thin little by little, well, you'll eventually probably have to thin it a lot at once to restore pristine performance. Thinning can be a pain, depending on your gear, so it might be easier to thin it bit by bit over the life of the blade than all at once.

To clarify, I'm no expert, and I'm not patronizing you at all: I assume you know most or all of what I wrote above. I just like to explain, it helps me, and if someone else gets something out of it, well, all the better.


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## JaVa (Feb 4, 2021)

big_adventure said:


> I like to say to people that nobody is "right" in this kind of discussion. The corollary is that the only person "right" in your kitchen is you.
> 
> Some knives "need" (read: would be optimized, for a certain user) thinning out of the box. Some don't. Some, hell, COULDN'T. I've got a Kurosaki bunka that would be "impossible" to thin: you can almost see through the blade as it is.
> 
> ...


I agree 100%.


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## Luftmensch (Feb 4, 2021)

It is so nice when the internet is civilised


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## big_adventure (Feb 4, 2021)

Luftmensch said:


> It is so nice when the internet is civilised



Isn't it, though? A little weird however. Shocking. Disturbing. If I had been possessed or kidnapped by aliens and replaced by someone else, would I know? Would anyone?


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## stringer (Feb 4, 2021)

I generally thin a knife once when I first buy it. I like to get the knife thin enough behind the edge that I see damage from regular use. Then I make the edge slightly thicker. After that I maintain the geometry with a tiny bit of thinning every time I sharpen. The only knife I have ever bought that I didn't think needed thinning out of the box was my Watanabe 270.

As a pro chef my knives (especially my beaters) were sharpened often. I expected them to do anything from chiffonadeing basil and brunoiseing mirepoix to splitting chickens and lobsters and chopping bamboo skewers down to size. I generally lose about a mm/year in edge height. But maintenance thinning can still be done with a few strokes on a 2k stone unless there's big chips.

Since the pandemic started I have been doing other stuff. My home knives won't really every need to be thinned or really even sharpened. They just see 1% of the abuse. I can maintain them indefinitely with a ceramic hone after my initial post purchase thinning.


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## Twotimehojo (Feb 4, 2021)

So for someone new to wide bevel sharpening, I have a few follow up questions for the crowd:

1. In general, when doing maintenance thinning, what grit stone do you start out?

2. In general, when doing maintenance thinning, do you go to forming a burr (essentially a zero grind)

3. In general, when doing maintenance thinning, do you also move to higher grit stone too?

4. In general, when doing maintenance thinning, how do you fix up the aes·thet·ics? 

5. ...is there ever a concern in removing the stainless cladding? 

I bet I am not the only one who is interested in these answers! Thanks!!!


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## stringer (Feb 4, 2021)

1. In general, when doing maintenance thinning, what grit stone do you start out?

Shapton Pro 1k

The second half of this video is a typical maintenance sharpening for me.



2. In general, when doing maintenance thinning, do you go to forming a burr (essentially a zero grind)


Depends on the knife. For a sujihiki or nakiri yes. For a gyuto it depends on how it's performing and how long I've been honing on a ceramic rod and how much damage there is to the micro bevel. 






sharpening with continuously changing bevel


I made a video of my sharpening routine. This is a demonstration of starting with the tip at a zero bevel and ending with the heel third at about 22 degrees per side. This creates a continuously variable "wide bevel". I start off with the tip flat on the stone. This helps me to keep thinning the...




www.kitchenknifeforums.com





3. In general, when doing maintenance thinning, do you also move to higher grit stone too?


Yes. I go from my 1k stone to my 2k super stone generally.

I very rarely sharpen kitchen knives beyond 2k



4. In general, when doing maintenance thinning, how do you fix up the aes·thet·ics? 

I sand the face of the knife after my initial thinning. Then I refinish it every couple of years.






Old Beater Meet New Beater


You know that feeling when you start getting bruises and cuts on your knuckles because you're favorite beater has been sharpened too many times? What can it mean? Only one thing. New knife day. Kanehide TK 240 3 years old vs new.




www.kitchenknifeforums.com





5. ...is there ever a concern in removing the stainless cladding? 

No.






Advice sought on rehabbing damascus


This is my wife's 180 mm Gyuto. She bought it on a whim from Japanese Knife Company about 7 or 8 years ago. It's Damascus stainless clad vg10. It gets used every day for home cooking. It has been sharpened regularly and thinned a little every sharpening session. The Damascus pattern is faded and...




www.kitchenknifeforums.com


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## Twotimehojo (Feb 4, 2021)

Thanks! Will check out all the links! Much appreciated.


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## Benuser (Feb 4, 2021)

stringer said:


> I can maintain them indefinitely with a ceramic hone after my initial post purchase thinning.


Is it the microbevel only you maintain? Just curious, as the ceramic rods I know hardly go beyond 2k. I guess, the microbevel gets widened quite fast under such a regime.


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## branwell (Feb 4, 2021)

JaVa said:


> So why all these knives need all this thinning?



I love the feel of the blade on the stones. I love all the combinations and all the different edges that can be produced. I love thinking I have found the perfect grouping only to discover with different steel, my new favorite shone is now my least favorite. Infinite entertainment.


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## stringer (Feb 4, 2021)

Benuser said:


> Is it the microbevel only you maintain? Just curious, as the ceramic rods I know hardly go beyond 2k. I guess, the microbevel gets widened quite fast under such a regime.



Yes I just hit the micro bevel. My ceramic rods are around 2000 grit probably initially but they are heavily burnished from constant use which makes them feel finer.

I didn't realize how coarse they make ceramic rods until I was at a friend's house about a month ago and she pulled one out of a drawer that was probably 120 grit. I don't know what maker but it said LC (maybe Lamson Cutlery?) on it.

That's when I realized there was as much variation in ceramic hones as anything else in this game. Below is a video showing how I use one of my hones. Just a sightly higher angle than where I finish normal sharpening. I resharpen usually not because the bevel had gotten wider so much as micro chipped and rippled. I don't know if I can catch it in camera, but an edge that has been honed a lot on ceramic will get this wavy look on the micro bevel.

I think the ceramic hone is fixing the micro chip damage a little, but more rounding out the burrs and high points. And also doing some damage itself. Eventually the damage accumulates enough where the knife starts catching and tearing instead of cutting no matter how much you hone it. And the ripples start to get annoying too. Then I go back to the stone. This still isn't anywhere close to what most people consider "dull" either.


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## Benuser (Feb 4, 2021)

Thanks, @stringer !


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## Brian Weekley (Feb 4, 2021)

Wow ... great responses.

Generally, I thin as I go. Provided I’m satisfied with the way the blade handles when I first get it my objective in thinning is to maintain the original blade geometry. During each sharpening session I’ll evaluate the secondary bevel and touch it up or not as I see it .... generally using a coarser stone than I sharpen with. On average I do this maybe every 4th sharpening session. Some knives seem to never require thinning. If I move to a coarser stone I’ll go through a full progression to maintain the edge and finish I desire. I don’t thin friends or customer’s knives. Too much work for very little return. Of all the knives that I’ve purchased through BST only one came desperately in need of thinning. It was used extensively in a commercial kitchen. I think I’ll try my Tormek T8 water stone @220 grit and see how it goes. I’m guessing 2-4 hours start to finish.


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## kevin (Feb 4, 2021)

Thick boy to thin boy


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## Brian Weekley (Feb 4, 2021)

Ouch!


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## tostadas (Feb 4, 2021)

big_adventure said:


> I like to say to people that nobody is "right" in this kind of discussion. The corollary is that the only person "right" in your kitchen is you.
> 
> Some knives "need" (read: would be optimized, for a certain user) thinning out of the box. Some don't. Some, hell, COULDN'T. I've got a Kurosaki bunka that would be "impossible" to thin: you can almost see through the blade as it is.
> 
> ...



You make excellent points. For the knives I really like enough to keep, I may thin it (once) to get it to the exact performance I want. And even then, it's minor. It would include flattening the bevel up to around 10 or 15mm from the edge, until it feels right. However, I dont think my normal home use will warrant any maintenance thinning for a LONG time, if ever.

Some of the knives I sharpen for family have been through lots of abuse, including pull thru electric sharpeners. I sometimes have to thin those for them so that they're back to at least a usable condition. I personally start with a 200grit stone if doing it by hand. If the knife is super bad, I'll pull out the belt sander with 80 grit belt, or 40 if the profile is trash.


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## tostadas (Feb 4, 2021)

kevin said:


> View attachment 112766
> View attachment 112767
> 
> Thick boy to thin boy


That's a significant amount of thinning! Looks great, what knife is that?


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## kevin (Feb 4, 2021)

tostadas said:


> That's a significant amount of thinning! Looks great, what knife is that?



Just a Kanefusa Fujiwara beater gyuto


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## tostadas (Feb 4, 2021)

kevin said:


> Just a Kanefusa Fujiwara beater gyuto


Did it come that fat stock, or had it been used extensively to get to that point?


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## kevin (Feb 4, 2021)

tostadas said:


> Did it come that fat stock, or had it been used extensively to get to that point?


Came pretty fat and became fatter after use


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## jwthaparc (Feb 6, 2021)

stringer said:


> 1. In general, when doing maintenance thinning, what grit stone do you start out?
> 
> Shapton Pro 1k
> 
> ...



Wow that angle looks like you've ground it to zero. I dont think I can see a secondary bevel. Maybe it's just because I'm watching on my phone.


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## captaincaed (Feb 6, 2021)

Bodine said:


> I'm sorry but 80 grit on a knife, I can not do that, I'll take the extra time.
> But I do not thin often.


I think a lot of rough shaping happens at 36 grit. There are always speed vs refinishing trade offs.


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## kevin (Feb 6, 2021)

Last thinning on a knife for awhile.


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## captaincaed (Feb 6, 2021)

kevin said:


> View attachment 113140
> 
> Last thinning on a knife for awhile.


You may be the new choil shot champ.


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## tostadas (Feb 8, 2021)

kevin said:


> View attachment 113140
> 
> Last thinning on a knife for awhile.


Is that done with a grinder?


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## tostadas (Feb 20, 2021)

I tried sandpaper on a flat atoma yesterday for thinning. It works really well, and saves quite a bit of time because I don't need to worry about stone dishing. 80grit 3m sandpaper cut pretty fast and didn't leave terrible scratches. Followed it up with 120 and 220. It feels ready to use at this point, but I'll probably go also 400,800 before taking it to naturals for polish.


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