New knife build - seeking feedback

[Shawn Pixley]

So the kitchen knife thread got me thinking, "hey, I have some Damascene steel I made a while back. Why don't I make a sushi knife out of it?" Yanagiba are long, slender knives that cut fish on one smooth pull stroke. I was impressed by the commentary from David, George, Stanley, Derek and others around the qualities of various steels and their utility as knife or edge material in various threads and in particular the kitchen knife posts.

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This billet is made 5160 spring steel and 203 low carbon steel. It is roughly the size needed for a long bladed Yanagiba.

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Typically the yanagiba or yanagi ba has a blade length of between 10 and 12 inches. It can be either partial or full tanged. I'm thinking of a full tanged version. The handle would be between 5 and 6 inches in length. It would be a single bevel (right side as I am right handed). So my process (questions) are as follows:

I plan to cut the shape using a angle grinder with a cutting blade as I don't have a metal cutting band saw.
I was going to create the bevel with a belt sander and a jig at the appropriate angle.
I will hollow the left, non-bevel side with files and coarse stone.
I was planning to harden using a peanut oil quench (that's typically what my wife and I use). I wasn't planning to clay the back.
I'll temper in the oven (did I mention my wife is very tolerant)
I would etch with muriatic acid.
I plan to pin the tang to the handle (I know this is not traditional). The handle would be some curly maple I have. It would get a silver trim and horn front if I can find some.

So my questions to the experts:

Am I missing anything? I'm mostly worried about cutting out the shape.
Is there a better way of hollowing the back?
Are there things I should do differently?
Any advice?

[David Weaver]

I'm clearly not the expert here about knife making because I've never made anything but marking knives. But I can relay what i've seen. Traditional japanese knives were scraped on the back. A few makers still make them that way, but very expensive makers (monzaburo or shigefusa? Can't remember which one I saw). Other than that, i can't comment much on the making process. I wish I could find a video of one of the makers scraping, because while it's not machine fast, they are scraping metal out of the back of a knife blank surprisingly fast.

I think the 5160/low carbon combination might come up short in carbon/hardness. Typical combinations for razors end up around 0.8 or 0.9 carbon, and both steels used are in the 0.75 to 1% carbon range (1095/15n20 is one I've seen).

I think 5160 might be more of a machete type steel IIRC where it's used.

I have only seen one person dipping a razor and that is mastro livi. He used ferric chloride mixed in water.

https://www.youtube.com/watch?v=VJENBAB85EE

(at 40 minutes for the ferric chloride - not that there's much to see)

Anyway, even in the 1095/15n20 combinations where the two steels aren't that far apart, the razors have a reputation for having one part of the mix not sharpening as well as the other - leaving tiny chipping in one part of the folded steel and a good edge elsewhere. I think you might get soft edges where the low carbon steel is - do you have any thoughts about how much of each was used, like was it a 1 to 1 mix?

[george wilson]

5160 has .60 carbon,which is very low. I would at least quench it in water. It probably will not reach full hardness in peanut oil.

No doubt it will warp being beveled on only 1 side,but you can heat it up to 300º and twist the blade straight while it is still hot. When cool,it would snap off,so work fast and bend it like a noodle while hot. Reheat if necessary.

I don't think this will make a decent knife,though. It may get sharp,but will not have a durable edge.

You don't need anything fancy to bring out the pattern. Lemon juice will do. I've even used clorox,but don't let the clorox etch the steel too deeply.

[Shawn Pixley]

Thanks David and George

I agree the steel is not ideal for a durable edge. When I was making this particular billet, I was working on my forge welding technique and I used a formula from the web. I believe there were 5 layers of 5160 and 4 of the other. It probably won't be the most durable edge but cutting filleted fish doesn't dull things too quickly.

David, I'll look up the scraping technique. That sounds interesting.

[David Weaver]

Just a side comment, because I neglected to say it earlier, regardless of the alloy, it's a really pretty piece of patterned steel.

[Shawn Pixley]

Thanks, I thought so too. Sometimes, even the blind squirrel finds the acorn...

[David Weaver]

Shigefusa, using a sen (at about 4:00). All it takes to make a sen is to have some good quality high carbon steel and temper it very little and profile a 90 degree edge or thereabouts. It doesn't have to be super sharpened (something like 400 grit is fine) as long a the edge is crisp.

https://www.youtube.com/watch?v=zNPc6xBBiLk

I think you could make one for one time or a few time's use by making a wooden handle and mounting a small piece of hardened carbon steel (you harden it, of course) that you drill, obviously before hardening. The huge sen the guy is using looks nice, but that'd be a lot of work to make and harden something that large.

[David Weaver]

Actually, watching the guy sharpen the sen, it looks like he's sharpening closer to 70 degrees. I'd do what he does.

[george wilson]

If you want a "square" or rectangular bar of steel type scraper,I have found it necessary to hollow grind the bottom of the scraper to make it cut AT ALL. The gunsmiths made a scraper of 18th. C. style like that for scraping sword blades. It would not cut,so they brought it to me to figure out(like everyone else did!) I ground a shallow hollow in the bottom,and it then had relief so it then cut quite well.

They also made a thread tap that would not cut. Once again,they had not ground relief into it.

[Bruce Haugen]

How much relief do you recommend for a scraper like that, George? I've made scrapers out of used up files. Some worked, some didn't and I never knew why. Maybe this is the answer?

[george wilson]

I used the 8" dia. contact wheel on the Wilton Square Wheel Grinder to get the concavity. Now,it is possible that an experienced Japanese scraper could just cock the rear end of the scraper up a bit to make the leading edge bite. But,that would take a lot of expertise to keep the scraper from just digging in and chattering. This could be counter acted by changing the angle of the scraper with each stroke.

sorry, I have had to be nursing my wife constantly these past few days since her surgery,and haven't had time to view the video.

[Ryan Mooney]

Don't grind the edge to fine prior to hardening or you'll a) risk burning it and b) possibly loose to much carbon unless you're firing it in charcoal or something similar to re-add carbon.

It is a pretty piece of steel, looking forward to seeing it in a knife!

[Fitzhugh Freeman]

Just a quick thought: When I made a few blades (cabinetry float, plane blades, small knives) I had trouble finding answers to a range of specific questions. In the end someone suggested I check out the various knife makers' forums (usually within a general knife oriented forum). It ended up being a great help since so many members make their livings making knives.

To be clear, I'm not in any way suggesting George, Ryan, David etc. are wrong! Just that you may find it useful since there is such a concentration of experience there.

Of course you have to be a lot more careful to ignore the would-be ninja types there than here. It's too bad most 13 year old boys don't find a chisel or hand saw as intrigueing as a huge knife with a spiky hand guard and a name like "THE ZOMBIE ABLITORATOOOOR!" And what is it with slicing up hanging dead pigs? ack. Ok, I've gone way way off topic, but truly, if you can put up with the vocal minority of odd types you'll find a much greater number of really helpful true artists who are as willing to share their knowledge as the greats here are. People who live and breath their art and are happy to share it with others, as we have here.

[Shawn Pixley]

So, I've made some progress on the yanagiba. I have the rough shape. I need to reflatten it and drill the tang holes. After that I'll rough cut the bevel and inlay the back. Then I'll hollow the back (left side). Then on to heat treating.

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My shoulder is tired from filing. It didn't help that it was hot here without any wind.

[Jim Matthews]

Wow.

How's your neck, after all that?
Will a wooden handle be fitted?

Will you give your knife an auspicious name?

[Shawn Pixley]

Neck is fine. It will have a wooden handle (probably inlayed cocobolo with fittings). It will be used solely for cutting fish. I haven't decided what to inlay on the blade. I still may work on the shape a little.

[george wilson]

So far so good. I am not into making Japanese knives,but I see little need for hollowing the back side,which is the operation which will give you the most trouble. I'm sure they have a reason for doing that,but I'm sure a simple knife will cut just fine without hollowing the back. You might consult Japanese knife afficionados about that,though. Other knives,including my LV Japanese kitchen knife,cut just fine without hollowing.

As for etching damascus,I have found Clorox quite effective. Some use lemon juice. I would avoid muriatic acid because it is VERY difficult to kill the blasted stuff!! Clorox will etch the pattern just fine,and TOO deeply if you aren't careful. Muriatic will etch it very deeply also. Lemon juice might be the safest stuff to use. If you use Clorox,just don't leave the knife in it more than a few minutes. Actually,Clorox uses the same chemical as muriatic acid to do the etching-chlorine.

I have found that keeping even a sealed plastic bottle of muriatic acid in the shop will sooner or later cause tools on the other side of the room to start rusting! No kidding,I had that happen years ago. I had to throw away the acid to make it stop rusting PLATED wrenches.

[Brian Holcombe]

I'll venture a guess that the hallow is something specific to sushi. Even a good german or French knife will drag through meat if you use it the same way a sushi chef uses their knife, So I'd bet the hallow helps to break the tension when slicing.

where are you guys buying Shigefusa? I want one :)

[george wilson]

i agree with you,Brian. I was just suggesting leaving the hollow out rather than attempting to grind it and messing the knife up,or causing interminable hours trying to get it right. I could grind it,but it takes a lot of practice,and a steady hand.

I made a special attachment for my Square Wheel grinder: A block of steel with a large radius convex curve on it. This is clamped on the platen UNDER the belt(which works just fine). It gives the effect of a hollow grind done on a much larger diameter wheel,like they used in the old days.

The Bowie and the amputation knife below were ground on the attachment. With the 8" wheel,it would not have been possible to get such a wide hollow grind. The curved hollow grind of the amputation knife was the trickiest freehand grind I ever did. I had wished the belt had a rounded face,as I'm sure the original wheel would have had,to fit into that curved shape. But,somehow I pulled it off with a flat faced belt. I had steadier hands in those days,though it wasn't really that long ago. My journeyman Jon made the handle. It looks upside down,but is not. The blade of the amputation knife is so thin on the cutting edge,it approaches a straight razor. The back of the blade is 3/16" thick. A very easy blade to burn while grinding,though I avoided that.

The amputation knife resides in the Apothecary Shop in the museum,where I must say,the ladies do an excellent job of keeping the surgical tools we made for them from rusting. I wish everyone else was so meticulous.

[Brian Holcombe]

Not sure how I missed this reply, those knives are gorgeous George. I have a couple blades I made out of d2 when I was a kid, I'll have to take some pictures.