Difficulty sharpening a petty!

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dafox

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Aargh!
This is the most frustrated I've been sharpening a knife.
It's a Fujiwara Kanefusa FKM 120mm petty, aus8.
I started sharpening it at an angle about like I usually do with my other knives but I wasnt able to raise a burr, used a Shapton pro 1K. Then i switched to a Sp320 and increased the angle, did raise a burr that way. I sharpened it about 70/30. Then I used the same angles and ratio using a Sp1k, got it pretty sharp but it snagged and tore the paper pretty badly during a cutting test. I went back and started with the 320 again and followed it with the 1k again and got it better. Did it a 3rd time with both stones and was even more diligent with controlled deburing strokes on both stones. Passes the paper cutting test better but it still snags and tears if you dont cut just right. I get my other knives screaming sharp with the same techniques. I've always had difficulty sharpening petties. What's up?
 

kayman67

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Try stropping between stones (not on fine leather) and try a mixed technique with edge leading on one side and edge trailing on the other (always finish with first), keeping in mind what side you are most comfortable with for edge leading.

How old is this knife? Maybe the edge got damaged and you will need to remove some more material.
 

vicv

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Yes it sounds like a deburring issue you have to keep at it. Also I wouldn't recommend raising a spine when you're having an issue raising a burr. I know it can be frustrating but you have to keep at it at the low angle otherwise you're going to get a very thick knife. I don't imagine it's a bad heat treat I trust stainless knife heat treat by Japanese makers a lot more than I do a carbon knife. I would try three or four Edge leading passes with the spine twice as high off the stone as you sharpen. With not even the weight of the knife on. That should grind the Burr off without thickening the edge
 

dafox

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Try stropping between stones (not on fine leather) and try a mixed technique with edge leading on one side and edge trailing on the other (always finish with first), keeping in mind what side you are most comfortable with for edge leading.

How old is this knife? Maybe the edge got damaged and you will need to remove some more material.
Its new.
I dont have any problem with the other knives that I have in this model, I also sharpened a 180 the same day, no problem.
 

dafox

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Yes it sounds like a deburring issue you have to keep at it. Also I wouldn't recommend raising a spine when you're having an issue raising a burr. I know it can be frustrating but you have to keep at it at the low angle otherwise you're going to get a very thick knife. I don't imagine it's a bad heat treat I trust stainless knife heat treat by Japanese makers a lot more than I do a carbon knife. I would try three or four Edge leading passes with the spine twice as high off the stone as you sharpen. With not even the weight of the knife on. That should grind the Burr off without thickening the edge
Thanks, I think you're right, its a deburring issue. I did end up sharpening it at my usual angle, just kept at it and focused on deburring better. It's still not as good as my other knives in this model, my 180 gyuto is easy to sharpen, I like the Shapton pro 1k edge on it, I use it for chicken butchery. I've never tried edge leading strokes, maybe it time...
 

vicv

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Thanks, I think you're right, its a deburring issue. I did end up sharpening it at my usual angle, just kept at it and focused on deburring better. It's still not as good as my other knives in this model, my 180 gyuto is easy to sharpen, I like the Shapton pro 1k edge on it, I use it for chicken butchery. I've never tried edge leading strokes, maybe it time...
Just a couple extremely light passes at the end. I will very often follow that with a couple of edge trailing strokes at my sharpening angle
 

dafox

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Just a couple extremely light passes at the end. I will very often follow that with a couple of edge trailing strokes at my sharpening angle
Thanks, my usual sharpening regimen includes ending on very light stropping strokes.
 

Benuser

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Stay as long as needed with the coarsest stone. Deburr by edge leading with the lightest touch. Only go to the next stone when you can't reduce the burr any further and it only flips. Rough split leather may help to clean up one side after which you deburr the other one, and vice versa.
 

MowgFace

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I have the most trouble with my shorter knives. They tend to have a more continuous curve so it’s constantly shifting angles of contact. I have to go super slow.
 

Benuser

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I have the most trouble with my shorter knives. They tend to have a more continuous curve so it’s constantly shifting angles of contact. I have to go super slow.
You will love this one.
Robert Herder's Yatagan. The only way I've found is in keeping the scratch pattern rigorously oblique to the edge.
 

andrewlefilms

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I agree with deburring between stones. I also prefer cheap stainless petties for cutting lemons and the sort and I find that along with light stropping on a course stone, it also helps to pull the knife through a soft wood to deburr, and then stropping again before moving on to another stone
 

kayman67

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Usually, I refresh mine with in hand sharpening. But I'm well aware this is not for everyone and since you guys mostly sharpen kitchen knives, somewhere that's not in the field on the go, I image this skill saw little to no development. This gives a much better feel and allows for changes that easily follow the bevel and the geometry.
 

bahamaroot

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You should be able to cut paper cleanly off the 320. If you don't have a sharp edge off that stone don't go to you're 1k. I think you're just not getting all the burr but otherwise doing fine. It's the steel not you.
 
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