Urisaki grinding

L

LemmonJello

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Jun 25, 2014
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Is there a way to grind a urisaki without using either a 36'-60" wheel, or using a belt grinder? I have some .125" 1084 and i'd like to make some single bevel knives for fun (yangi, usuba, tokobiki). I'm not really interested in buying a $30 Harbor Freight 1x30 but have spent my money on quality files instead. My thought was to cut out a couple 3-5 foot diameter circular segments with a router and mount some undetermined grit of sandpaper on to the segments and attack by hand. Is this feasible, or am i asking for either more work than it's worth or will I just scratch/mar the hell out of the back side and ruin it completely?
 
Doing it by hand would probably be doable, but would be a heck of a lot of work... I would think that it would be more work than it's worth. If you go with a full flat grind down to almost a zero edge, and put a slight convex edge on it, I think you would be fine.
 
I have a thread where I discuss grinding URASUKI somewhere. I think it is in the yanagi-ba WIP.

What you do is use the largest contact wheel you have available. Lets say it is a 10" wheel. Here is how to do it:
If you grind with the blade at 9:00-3:00 position (horizontal), the grind will be a 10" hollow grind.
If you grind with the blade at 12:00-6:00 position ( vertical), the grind would effectively be a flat grind....or an infinite arc.
If you hold the blade at 10:00-4:00 position ( slightly diagonal) it will equal an arc between infinity and 10" diameter.
Using a piece of scrap, you can figure out at what diagonal you need to hold the blade to grind the urasuki in a fairly even pass. It takes a bit of a wiggle sometimes, but works a lot better than trying by hand.
Clean up by hand with sandpaper.

Tip:
Grind the urasuki right up to the edge and spine...almost touching them. After cleaning it up with sandpaper to 400 grit, flatten the back on a stone or flat platen (I like a stone) until you get the upper and lower flat borders as you want them. I use about 1/8" to 1/4" flat border on the urasuki. Urasuki does not need to be deep, just an even and shallow hollow area.
 
He was asking about doing it by hand, Stacy, so not sure if this will help him a whole lot. I have a 36" radius platen from Nathan that is excellent for this application, but I would think doing this by hand would be really tedious...
 
I've done one without a large radius wheel... and mostly by hand. It was a lot of work, and I probably wouldn't do it again (especially since I've since purchased a radius platen).

I pretty much did it in just the way you described... only I did some of the initial grinding with an 8" contact wheel to establish a "track" for myself and do some bulk removal. You could probably carve or scrape the steel like people do with fullers to accomplish the same thing, but I don't have any experience with that. Once it was thinned a bit, I made myself a large radius sanding block and went to town.

Use a smaller radius than you intend to end up with for the hollow. You can work it in to a larger radius by "pushing" it at the edges of the hollow and feathering it in. I also kept a coarse water stone handy to check my progress. Every few minutes, I'd make a few strokes on the Uraoshi (I think that's the right word?). This would help me identify any spots I needed to work more or avoid on the hollow by the thickness of the line. If it was thick, I'd "push" the hollow into that spot a bit more... if it was thin I'd avoid the spot. If you end up "breaking" the line at any point, you'll have to work the whole thing flat, or you'll end up with a wave in the edge. I also did the final geometry on the single bevel at the same time, so the whole thing ended up sharp and ready to cut by the time I was done.. The whole thing was just a whole lot of back and forth to tweak everything in properly.

Not sure if any of this makes sense... but it worked for me. That said, I wouldn't do it again. I don't know what kind of knifemaking experience you have... but if you're just starting out, I wouldn't even think it. However, if you have a good bit of experience making knives by hand, and aren't afraid of some hard work and headache, go for it.

Oh, and I should also mention... since you're working with hand files, that probably means you're doing most of your removal pre-heat treat. Single bevel knives do funny things in the quench. I would recommend doing most of the work, especially on the Urasuki, post heat treat. A small warp would negate all of your hard work honing everything in.
 
Grinding the urisaki by hand using sandpaper would be a massive amount of work.

If I were going to do everything by hand, I would omit the urisaki.

I grind mine in with 14" contact wheel or a 36" radiused platen and it still takes a bit of effort on hardened steel.
 
I tried Bladsmith's method of grinding at an angle and it works well. It is a tricky grind to pull off that way and took me a bit of hand sanding. Check the Yanagi-Ba WIP Bladsmith did.
 
Sorry, I missed that part....mea culpa!

To do it by hand isn't impossible, but it requires a different technique than most would think of.
It is easiest done by moving the blade against the abrasive. Normally it is a rounded stone, but many things will work. Clamping/tacking a strip of 100 grit wet-or-dry abrasive across a curved surface ( cut out of a 2X6) is the simplest. The abrasive surface must be firmly mounted, because you are going to be pushing hard against it. Hold the blade by the tang and tip and work it in short, overlapping, and firm strokes as you make the hollow. Once rough ground in, switch to finer abrasive sheet, and then finish by hand sanding with a folded pad of abrasive.

The alternate method is to clamp the blade down and use curves stones called "slip stones". This is a bit of a skill.

Final alternate is to use a 4" sanding disc in a drill or angle grinder. Firmly clamp the blade and slowly make the hollow. Finish by hand.

On all these take your time........... and do a practice piece first.
 
by hand i woudl think a scraper first but then like stacy said grinding it in on a rounded stone ether way finish with sand paper
 
Lloyd, you and I might do it with a sen...but a new maker with no power equipment won't have or be able to make a sen. The curved surface is probably his best choice.
 
From a blacksmith's point of view, wouldn't it make sense to just tap the blade into a recessed form and give it a very slight arc? Kind of like when you make a gouge...
 
Again, if he could forge, he could do a lot of things, but he is only an inexperienced maker with apparently few tools, I doubt he will be able to forge in a hollowed back and then grind the necessary bevels.


FWIW, forging in a hollow on one side only on a blade takes extreme skill. Just working the other side to straighten it up will remove some or all of the concavity. As mentioned, it would also require a grinder for clean up and flattening for a Japanese blade.
 
Agreed- getting a hollow with the edges ending up perfectly true to a flat surface would be challenging, and maintaining that through heat treat would be even more so.
Makes me want to try it! :)

bladsmth said:
Again, if he could forge, he could do a lot of things, but he is only an inexperienced maker with apparently few tools, I doubt he will be able to forge in a hollowed back and then grind the necessary bevels.


FWIW, forging in a hollow on one side only on a blade takes extreme skill. Just working the other side to straighten it up will remove some or all of the concavity. As mentioned, it would also require a grinder for clean up and flattening for a Japanese blade.
Click to expand...
 
elementfe said:
Agreed- getting a hollow with the edges ending up perfectly true to a flat surface would be challenging, and maintaining that through heat treat would be even more so.
Makes me want to try it! :)
Click to expand...

If you do, try a wide radius top fuller.
 
That would be a good approach, I was looking at the semicircular cutouts in my big swage block....tap tap tap cuss tap tap :)
And, guaranteed, I'll do the first one backward (leftie)
 
Thank you for all the helpful replies. While new and inexperienced i do have patience but i also am old enough to have the wisdom to think that maybe i should get a few knives under my belt before i try and tackle the urisaki. I was hoping to make as traditional a knife as possible but seeing how there is already a rather steep learning curve to this art already I think i'm going to save this aspect for another day. Though I do like the idea of moving the blade against the abrasive rather than the other way round. We'll see. Thank you again for all the helpful advice.
Mark
 
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