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Help Finding edge Angle of Japanese Knife

Started by Heli_Guy, November 21, 2018, 11:56:59 PM

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SteveHarbour

Heli-Guy.  It looks from the photo that you have an asymmetric knife.  As you may have figured out, these knives are ground for use with one hand and not the other.  As you hold the knife and look down on it, if the bevel is on the right side, it is a right handed knife.  It will push the sliced material to the right. 

As others have mentioned, many of these knives were meant to be sharpened on true, flat water stones.  The angle when using water stones varies but most are 11 to 15 degrees per side.  Shun knives are 16 degrees. 

Recommend that you do yourself a favor and find out how the knife was sharpened.  If it was a very low angle, like 11 degrees, learn how to sharpen with it with water stones. It's fun and you will get a wonderful edge.  Please don't screw up your knife by trying to grind a bevel on it.  I see this all the time.

wootz

#16
A Japanese knife with asymmetric grind sharpened on Tormek by our customer Kent (Sweden) sharper than a razor.
YouTube Video
https://www.youtube.com/watch?v=iQ9OQepVlR0
Looks like the knife has bitten his left index finger  :)

Kent's sharpening routine is Tormek SG wheel or a pair of CBN wheels to #1000 - Tormek SJ wheel (# 4000) - Paper Wheels with fine diamonds - and finishing on Tormek leather wheel with Chromox (using FVB for angle control).

Kent determined edge angle on each blade side with a CATRA laser protractor, and maintained the correct grinding and honing angle for each side on all these wheels using our computer software.

Superb result! - but most importantly is that for him it is a repeatable technology, a routine. Quality Japanese knives Kent sharpens within 30-37 BESS, sharper than the Gillette razor.

Our video about the CATRA laser protractor: https://youtu.be/rv2ulY6Less
.

cbwx34

Quote from: wootz on February 27, 2019, 11:36:22 PM
A Japanese knife with asymmetric grind sharpened on Tormek by our customer Kent (Sweden) sharper than a razor.
YouTube Video
https://www.youtube.com/watch?v=iQ9OQepVlR0
Looks like the knife has bitten his left index finger  :)

Kent's sharpening routine is Tormek SG wheel or a pair of CBN wheels to #1000 - Tormek SJ wheel (# 4000) - Paper Wheels with fine diamonds - and finishing on Tormek leather wheel with Chromox (using FVB for angle control).

Kent determined edge angle on each blade side with a CATRA laser protractor, and maintained the correct grinding and honing angle for each side on all these wheels using our computer software.
...

Actually, more questions than answers...

Is it an "asymmetric grind' knife, or a symmetric knife with an asymmetric edge?  (There's a difference).

Is the asymmetric edge intentional, or as discussed earlier, the result of being hand sharpened? And should this asymmetry be maintained or "corrected"?  Was it a customer request, and/or would the customer know the difference? Etc....

Most of the earlier discussion and info on the web discussed earlier suggests Yaxell knives, like the one in the video are, or at least suggested to be, sharpened at 12° per side... and the hand sharpening might produce the unequal bevels... doesn't necessarily mean it's "correct" and should be followed.
Knife Sharpening Angle Calculator:
Calcapp Calculator-works on any platform. New url!
(or Click HERE to see other calculators available)

wootz

#18
Quote from: cbwx34 on February 28, 2019, 02:44:44 PM
Actually, more questions than answers...

Is it an "asymmetric grind' knife, or a symmetric knife with an asymmetric edge?  (There's a difference).

Is the asymmetric edge intentional, or as discussed earlier, the result of being hand sharpened? And should this asymmetry be maintained or "corrected"?  Was it a customer request, and/or would the customer know the difference? Etc....

Most of the earlier discussion and info on the web discussed earlier suggests Yaxell knives, like the one in the video are, or at least suggested to be, sharpened at 12° per side... and the hand sharpening might produce the unequal bevels... doesn't necessarily mean it's "correct" and should be followed.

If only the Japanese were interested in Westerners' opinions of the Japanese sharpening tradition... they would not appreciate them "correcting" it.
Even though studies have shown that double-bevel edge outperforms single-bevel, we do not double-bevel every single Japanese knife, the same with asymmetric - understand the givens, follow them and put the sharpest edge the steel allows.
http://knifegrinders.com.au/SET/Double-bevel_outperform_Single.pdf

On quite a number of occasions I was asked to restore original edge profile on a Japanese knife botchery-sharpened "European way".
You can keep questioning while we keep sharpening.

cbwx34

Quote from: wootz on March 01, 2019, 10:10:35 AM
If only the Japanese were interested in Westerners' opinions of the Japanese sharpening tradition... they would not appreciate them "correcting" it.
Even though studies have shown that double-bevel edge outperforms single-bevel, we do not double-bevel every single Japanese knife, the same with asymmetric - understand the givens, follow them and put the sharpest edge the steel allows.
http://knifegrinders.com.au/SET/Double-bevel_outperform_Single.pdf

On quite a number of occasions I was asked to restore original edge profile on a Japanese knife botchery-sharpened "European way".
You can keep questioning while we keep sharpening.

Thanks for the compliment.  "Questioning"="learning" (as opposed to, I dunno, repetitive motion?)  ::)

I'm not sure why you introduced a "Double bevel" vs. "Single bevel" study into this... not really the issue here.  (Your study, from what I can tell only looked at single bevel knives, which, while asymmetric, doesn't mean it will apply).  Maybe take another look at the questions?

More and more knives labeled "Japanese" are not ground nor inteneded to be sharpened asymmetric.  Another thought, most that are, are labeled for right or left handed use... another point I don't see on the knife shown in the video, or in their advertising.  It's why I asked, I don't have one to look at.

A lot of knives, both Japanese and Western come with asymmetric edges... doesn't mean they were intended to be that way, nor should they necessarily be maintained or resharpened that way, is what I'm saying/asking here.
Knife Sharpening Angle Calculator:
Calcapp Calculator-works on any platform. New url!
(or Click HERE to see other calculators available)