Yanagiba geometry

H

Hesparus

Joined
Oct 31, 2004
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Hi Everyone,

A friend of mine has asked me to make him a yanagiba with traditional geometry. I've never done this before, but I'm taking this as an overdue opportunity to learn. This will have a 10" blade and be made from 52100.
The urasaki will be the most difficult thing for me to do, but I have read all of the posts about turning the blade at an angle on the wheel, so I at least have a road map for how to do that. I will be making at least 2 yanagiba and a couple other single-bevel knives so I will have more than once chance to get it right.
My biggest question is about the blade thickness and distal taper. My research has turned up yanagiba that are anywhere from 1/8" thick to 3/16" thick (and I know that thinner than 1/8" is getting into fuguhiki territory). Some people say there should be a little bit of distal taper, others say there should be none. Some say that for a 10" blade, 3/16" stock should be used, but I've seen a lot at that length that are 1/8" or in between. No doubt there is a lot of personal preference in here, but are there any standard guidelines for thickness and taper?
Thanks,
Chris
 
I like a 25%-30% distal taper.
The blade profile should taper in the last 1/3 of the blade toward the tip .... giving it the "willow" leaf look of the name (willow blade).
Blade length of 240-250mm (10") is just right for me. Wa handle of 150-160mm (6"-6.5").
Blade width about 30mm (1.25")
I prefer the blade about 3-4mm thick ( .125-155") at the handle.
Single bevel with shinogi 60% up from the edge (ha). Shinogi follows the edge, not the spine (upper bevel tapers toward tip), edge bevel is pretty much straight and even).
Urasaki is from about 3mm above edge to 6mm from spine.

Ni-mai ( high carbon back and ha, and low carbon or WI front) is great for a yanagi-ba, but san-mai will not work.
 
Stacy, do you grind before HT? How much if any of the bevel do you forge in?
 
Stacy: Perfect! That's exactly what I was looking for. The design I'm using is from Murray Carter's "101 Knife Designs."
In the yanagiba that I have seen, the bevel appears to be the same width for the whole length of the blade--if the thickness is tapering slightly, does that mean that the bevel angle should get slightly more acute to keep the height the same?
Thanks!
Chris
 
On a yanagiba, I grind the bevels and urasaki post HT most of the time. I only profile the blade and add the distal before.
If the blade is thick, I might pre-grind a very basic bevel and leave a very thick edge.

Using quench plates for stainless, and quenching carbon blades in fast oil followed immediately by quench plates will take care of warp and twist.
 
Stacy E. Apelt - Bladesmith said:
On a yanagiba, I grind the bevels and urasaki post HT most of the time. I only profile the blade and add the distal before.
If the blade is thick, I might pre-grind a very basic bevel and leave a very thick edge.

Using quench plates for stainless, and quenching carbon blades in fast oil followed immediately by quench plates will take care of warp and twist.
Click to expand...

I would second post-HT grinding-a beveled ni-ha blade can go seriously caddywumpus in the quench if there's a lot of dimensional variation
 
This is a very serious project to take on. Kudos for taking up the challenge. You will have way more hours into this than you think most likely.
But you will learn a lot about your steel and technique.

Regarding the urasuki, what wheel are you planning to use? Cocking the blade on the wheel isn't as straight forward as you might think on this one.
The heel and tip will be quite challenging. Tell us about your experience if you will.

Best of luck to you, and can't wait to see pics.
:applouse:
 
I've got an 8" wheel on my grizzly. I know it's far from optimal, but I'm going to see how far it gets me. If it doesn't work, I can wait until I have a better setup. Grinding the heel is the part that I'm most worried about. I'll for sure let everyone know how it goes.

Chris
 
Hesparus said:
I've got an 8" wheel on my grizzly. I know it's far from optimal, but I'm going to see how far it gets me. If it doesn't work, I can wait until I have a better setup. Grinding the heel is the part that I'm most worried about. I'll for sure let everyone know how it goes.

Chris
Click to expand...

If your height is reasonable and your thickness is there it might work out on a straight grind on an 8 inch wheel. You might try digging a partial 8 inch trench and finished that by hand with a wider radius. I have no idea if that would work out, but it might be worth a shot.
I have a 14 inch wheel and it seems to work very well, but I'd love one of those $$$ 22 inchers.
 
I'm doing a couple of test pieces first to see what I need to do to make it work. One of them is a mioroshi deba that is 3/16" thick and 1.5" wide, and I'm going to see if I can just do a straight grind. I'm also thinking of doing a 3/16" thick yanagiba to give myself more depth if I need it, even if that's a little bit on the thick side. So the bottom line is that I've got some other pieces on deck that will help me learn the technique and understand my equipment.
Thanks for your thoughts!
Chris
 
I've done them on an 8"-i pretty much did two parallel fullers and blended them together-you can't really tell it wasn't done all at once.
 
Would a 36 inch convex Nathan platen work? I got the impression that the Japanese smiths do them on the big wheel or scrape them?
 
I also have a 72" which I might try first on a blade that narrow.
 
It's been warm enough to be in the workshop lately, so I got this one started. Profiled and mostly tapered:

16729384_1313343855401994_2705293159918487404_n.jpg


This one may end up being a trial run instead of the final product. I didn't have any 1/8" stock on hand, so I had to go a little thicker. 33.5mm wide at the heel. It's 4.6mm thick at the heel and 3.6mm thick at the tip. Still needs a little bit of work on the taper, but it's most of the way there.

- Chris
 
Thanks! I'm going to shoot for taking the bevel up to the ricasso, since that seems to be what I see on other yanagiba.

Chris
 
Hesparus said:
Thanks! I'm going to shoot for taking the bevel up to the ricasso, since that seems to be what I see on other yanagiba.

Chris
Click to expand...

Agreed. You might have to consider your ricasso height though. The reason I mention this is due to the sharpening challenge. These knives are NOT easy to sharpen, and a wide blade road is going to add to that difficulty. And then the angle is probably more important and should drive the height line. Just something to keep in mind before you grind to give it some thought.
One other thing I've found on the urasuki sharpening, if you use a course (400) stone on the back side the loose grit off the stone may scratch the arched portion. It doesn't take much to flatten and sharpen this side, so you might try 1000 on this side to start to keep that issue to a minimum.
 
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