Ura(hollow) Hand sanding Jig

Does anyone know of a hand held devise that mimics the radial of a water wheel, that is for evening out the hollow on a single bevel knife? I know that evening out a hollow by hand would take forever, but this would also make hand sanding the hollow of knives for finishing purposes faster than using my soar fingers!

In a pinch and maybe the convexing is too prominent.

http://www.japanwoodworker.com/Product/160147/Convex-Sander.aspx

Badgertooth said:

In a pinch and maybe the convexing is too prominent.

http://www.japanwoodworker.com/Product/160147/Convex-Sander.aspx

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better than what I got, good for high spots too. Thanks! Keep it coming!

Make it... Take a block of wood the right size for what you are doing, sand the right convex into it with a stationary disc or belt sander, attach a long piece of wood transversely to get a two handed grip, and glue some hook & loop to it or use PSA sandpaper with interchangeable blocks. DIY version of what you can see them do in Japan in YouTube videos to hand finish ura.

Alternative: use a conformable piece of dense rubber (Think pencil eraser firmness.) with sandpaper. Cushions your fingers.

- Steampunk

Steampunk said:

Make it... Take a block of wood the right size for what you are doing, sand the right convex into it with a stationary disc or belt sander, attach a long piece of wood transversely to get a two handed grip, and glue some hook & loop to it or use PSA sandpaper with interchangeable blocks. DIY version of what you can see them do in Japan in YouTube videos to hand finish ura.

Alternative: use a conformable piece of dense rubber (Think pencil eraser firmness.) with sandpaper. Cushions your fingers.

- Steampunk

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Wish I had that kind of time to go to home depot, but unless its for sharppening I have zero tools, saws or electrical sanders etc in my loft :groucho:

I'm trying to address a similar problem and maybe one of those atoma sheets stuck on to a block like the one posted by badgertooth? I was thinking convex the long way not the short way though. You should try to keep the ura grind going north/south right?

[video=youtube;zNPc6xBBiLk]https://www.youtube.com/watch?v=zNPc6xBBiLk[/video]

11 minute mark, but move the stone 90 degrees and make it convex

cheflivengood said:

Wish I had that kind of time to go to home depot, but unless its for sharppening I have zero tools, saws or electrical sanders etc in my loft :groucho:

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You can do the same thing with a small handsaw, a rasp, some sandpaper, a small hand drill (Optional, but will make it much easier.) and a screwdriver or a hammer to create the fastening for the two pieces. You can buy wood and tools online, as well as at Home Despot.

In this case, zero tools sounds like a problem that is fixable, even for a loft-dweller. Small project, little mess, no skill.

- Steampunk

P.S. That tool in the Shigefusa video is exactly what I am suggesting you can make. He uses actual stones rather than sandpaper, though.

This is awesome! I've been trying to figure out a good way to thin a few beaters right behind the edge without grinding on a wheel. Must give this a try!

I may look up the shipping for you or ask someone to forward it once it gets to USA , one of the local tool makers here on down under made a run of 72"platen to mimic the water wheels and also he made a sanding block to fit the same radius , it is made out of aluminium and very cool gadget to have

chefcomesback said:

I may look up the shipping for you or ask someone to forward it once it gets to USA , one of the local tool makers here on down under made a run of 72"platen to mimic the water wheels and also he made a sanding block to fit the same radius , it is made out of aluminium and very cool gadget to have

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NEED. Are there any pictures?

Grinding a hollow into a hardened steel (provided this is grinding a used up blade, not cosmetic finishing) by hand is a pretty impressive feat, which personally, I would not undertake.

Marko Tsourkan said:

Grinding a hollow into a hardened steel (provided this is grinding a used up blade, not cosmetic finishing) by hand is a pretty impressive feat, which personally, I would not undertake.

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Haha yes, its only a one inch section Im evening out, but it will take forever Im sure. Bought some high quality paper at 80 and 120 grit, and I have the week end off haha

I use the round side of rubber hand sanding blocks. Approach the block at different angles until you lock up to the ground radius, which is similar to how they grind the backs on the water wheels. *Note - how the grind lines run at an angle (diagonal) to the blade - never top to bottom.

Marko Tsourkan said:

Grinding a hollow into a hardened steel (provided this is grinding a used up blade, not cosmetic finishing) by hand is a pretty impressive feat, which personally, I would not undertake.

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Agreed!

I use my sanding blocks under belts on the grinder when I need to remove steel. Doing it by hand on sanding blocks is for cosmetic use only.

There's also a way to fix/correct the ura using a stone (stick) attached (at a right angle) to a section of wood (used as a handle) where you go back and forth into the ura along it's length. This allows to carve out cleanly without blowing out the flat sections near the edge. I guess you'd then clean it up with finger stones. I've never trued this myself but seen it online before, seems to work nicely in skilled hands.

Greg at Wabocho uses this device he calls an ura fixer.
I often come across damaged or worn ura so this issue is of great interest to me

That looks just like what I was talking about. Thanks for sharing that Doug.

cheflivengood said:

NEED. Are there any pictures?

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For some reason I can't load pic , I will send over instagram