How do I touch up a Sashimi Hocho?

I did sharpen my Yanagiba, I sharpen it without any secondary evel. After 6000 waterstone I proceed with Green Rouge. It make me able to split hair, but I can not whittle it - I tried hard, make steel into mirror, but it just did not work. May be it has something to do with Shirogami properties, may be exteremely small angle is responsible for this, may be I need to use glass or 15000 waterstone - I do not know.

Anyway it is very sharp and probably sharper then it was when I just bought it. At least it works exceptional on kitchen with shin-skin tomatoes.

No problem on the edge detecter so far even it is very thin - no cheaps, no bends.

I get 8000 Norton waterstone to finish up, but I have impression that it is more coarse then 4000 King waterston. Am I wrong?

Thanks, Vassili.
 
I have two Japanese single bevel kitchen knives with a hollow face, one with a 30 deg bevel the other with a 22.5deg bevel. I don't know if this is standard practice, or how much it applies to the knives in this thread but for what it's worth :) I think of sharpening them like a chisel, making sure that the hollow side is sharpened completely sharp up and down the edge on a flat surface or stone before sharpening the bevel. Then I sharpen the bevel. Next I return to the hollow side to shear any burr. I do this in the basic grit/flattening routine already described.

Note: once I have established that the hollow side is sharpened to the edge on a flat stone I don't do much work on this side in subsequent sharpenings.

Vasssili,
I bought these knives to do a whittling-type, scraping motion to remove cane on an oboe reed, a soft material about .1mm in thickness in key areas so they have to 'catch' shavings .01mm thick or less with control. Even when the knives are very sharp and polished I don't think that they scrape as well as a double-hollow or flat grind. I have tried finishing with Chromium Oxide on leather, fine grits.

Another thing --I find with these knives is that I have to use a different rake angle than with other edge geometries. Could be that you need to hold the knife at a very different angle to get it to pass some of your tests.
 
Annr:
30 Degrees on a single bevel Japanese kitchen? I thought they were always like 10 or less. Is this angle for some special use. Heavy duty etc?
 
LJK,
Good question. Both knives were gifts. In the case of the 30deg beveled knife I was told that it is a Japanese cooking knife that had been co-opted for making reeds because of the superior properties of its layered steel. I and another BF member searched the web looking for a comp. and the closest thing I/we could find was an eel knife (I think). It looks to me as though the knife has been shortened to a 3" blade.

The toughest thing I use it for is to shave layers of cane (grass), w/ an outer layer of bark. The blade's edge makes contact with metal in the process , so I guess it gets a fair beating. It looses the keen edge fairly quickly. I could post a photo if you wish to see. It's really a wisp of a thing.

I didn't mention that since the bevel is so tiny sometimes I use "side sharpening" when I get tired of holding the blade.
 
Annr: Yes, if its not to much trouble please post some pic's. Thanks. So these knives did not work out as well as you had hoped? Maybe reprofiling to a lower angle would improve performance. But than again I really don't know what I'm talking about since I'm the one who started this asking for help. :confused:
 
There is many types of Japanese kitchen knives. Yanagiba, Deba, Adjikiri, Santoku, Kuboyashi, Kuri Muki, Ko-janagi, Sekium, Hamakiri... Single and double beveled - depends on it's purpose.

Best representation I found on (all that names I get from there...):

http://www.dick.biz - german website, but they have English Version.

I bought some knives and bladeas and australian wood from them - exclusive source for this kind of things.

There is even Japanese machete - Nata, also single beveled and it has like 50 degree edge...

But sashimi hocho (knife for sashimi) - Yanagiba, to my understanding do not suppose to have secondary bevel. Of course cheap ones can not hold high angle, but mine was handmade by Minomoto Mizuno and cost over $220 with hamone and everything.

2 thombrogan
I'll give 8000 Norton (yellow) a try - may be this is why I can not make it whittle hair - we'll see...

Thanks, Vassili.
 
LJK,
Here are links to pics of my knives: both sides and the whole knife. There are some funny shadows but I hope you can see the general size and shape. The blade is 3" in length. I don't think that it is super expensive, maybe $75.
http://http://ph.groups.yahoo.com/group/tormekusers/photos/view/96de?b=3&m=s&o=0
http://http://ph.groups.yahoo.com/group/tormekusers/photos/view/96de?b=2&m=s&o=0
http://ph.groups.yahoo.com/group/tormekusers/photos/view/96de?b=1&m=s&o=0
As far as how they work: there are some things that I would change about the blade shape and handle to make it more task appropriate and as I mentioned I don't find it ideal for the most sensitive work. But the knife sharpens easily and holds an edge well compared to the alternatives. It's taken several attempts to get it really squared and near that weird tip it is still a work in progress.
Now it sharpens in a few minutes or seconds even. I do hone it daily and touch it up as I work so that the edge never gets ravaged. I work from 1-9K grit and then finish with the charged leather. Maybe some of this will apply in a general way to your question.
 
You're welcome. My bad. A BF member emailed telling me that the links won't work unless one joins the site where these are posted. I had trouble resizing the photos to post them here, but I'll give it another shot. I need to figure out how to do this.:)
 
Yesterday I checked our local Japanese store with $20-$30 yanagibas as well as other knives with single bevel - they all do not have any secondary bevel, however I may see that bevel is slightly convex, so I guess my conclusion is right - no secondary bevel suppose to be there.

Thanks, Vassili.
 
Hi LJK,
The blade is about 2 3/4" long;
the bevel 4mm;
the blade is 10-13mm high
spine 2mm thick
30deg bevel

Since one of the priorities with these knives is to keep both the bevel and the hollow side flat I just wanted to share with you that sometimes I put the bevel on the stone and move it sideways. This makes it easier for me to keep the bevel in contact with the stone at all times since the knife is so tiny and there is almost nothing to hold.

Also, note that I did not sharpen the hollow unevenly, it came that way. The reason I feel confident of this is that I have sharpened it on a glass -backed abrasive.

How's your knife?:)
 
That's interesting thanks for posting pics and info. I have not yet sharpened the Shashimi Hocho that started this post, its a friends, but have praticed on some wood chisels with good results. As soon as I get the feel of a few new waterstones I required for this project. I'll be ready. ;)
 
I should mention that I got the idea for this technique from watching the DVD entitled "Side Sharpening " with Harrleson Stanley, in case you want to see this done professionally.:)
 
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