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danielomalley
05-16-2013, 01:06 AM
One of the projects that I've frequently asked to do is make saya. We try to stock a pretty wide range of saya, but there are always some knives that just don't fit. Plus, a custom saya can be a perfect fit and shouldn't need a pin to lock the knife in place. This is one that I put together last week for a chef down in San Francisco. She had just got a Yoshikane SLD santoku and wanted something that would make transporting it easy and look a little nicer than an edge guard.

I've seen some varied methods on this, but this one works pretty well for me. I generally make saya from ho wood, bass wood, or alder. All three of these are soft and so don't tend to dull knives. All three also have a pretty good amount of spring to them, so they can produce and maintain a pretty tight fit. My goal in fit is to have friction hold the knife in without need for a pin. Also, ideally the edge can't come into contact with the wood, but is instead held upward by the wood's natural 'spring'.

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First I slice the wood into a thinner and thicker section. Both are sanded to be as perfectly smooth as feasible. I sketch the outline of the knife into the thicker section. This gives me an idea of what the hollow needs to be. I'll extend the outline slightly toward the front so that there is a little leeway inside.
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I then begin to chisel out the inside. It is important that the flat is very consistently smooth. If it isn't smooth enough, only a few points will be in contact with the knife. This tends to make it 'stick' coming in and out and can scratch the knife over time. I start out with relatively narrow chisels and flatten with wider chisels.
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There's a lot of testing for proper fit during the shaping of the interior. I will frequently wet the blade with camellia oil and insert it into the carved section. This helps me see where the blade is connecting with the saya.
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Once I've carved out the inside I sand the shoulders of the carved side just a bit, to make sure it is perfectly flat. Then it's glued and clamped. I use a standard outdoor (waterproof) wood glue. Did I mention that I use a few clamps?
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After that I sand away the outside so that both walls are the same shape. I carve the top into a mune and round the bottom. I want the sides pretty thin. This gives them quite a bit of spring. Stresses will be put on the saya while it is being used to transport the knife. Because a knife will be inserted when the stresses happen, if properly fit, it doesn't need to be thick to be strong. If the fit is too loose, saya tend to crack while they are used for transporting, since it is only relying on the wood for stability, rather than a solid mass of wood, metal, and more wood.
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In the end, fit is pretty much everything. My goal is that I can hold the saya and shake pretty energetically. Not only should the knife not rattle at all, but I want it to stay put ... at the same time, it needs to be pretty easy to pull out when you are trying to.

-daniel

El Pescador
05-16-2013, 01:14 AM
Thanks for sharing. How do you feel about hardwood sayas?

Von blewitt
05-16-2013, 01:19 AM
Thanks for Posting this Daniel. Very informative. Although I'm sure you make it look easier than it is

Patatas Bravas
05-16-2013, 01:35 AM
I sort of like the idea of pins, in which case I suppose the saya's fit needs to be less precise, right?

On the other hand, the pins... I guess it'd be another task producing these onself, and seems you' d need a different (harder) wood too.

danielomalley
05-16-2013, 02:08 AM
Thanks for sharing. How do you feel about hardwood sayas?
I'm not a big fan of hardwood sayas. They look beautiful, but I don't think they serve function as well. A few years back, I had one Japanese saya maker that I was visiting tell me that soft wood sayas are for knives that will be used. Hardwood saya are for knives that are looked it.

They sure can be beautiful though.... I've thought about lining a hard wood saya with a softer wood, which might be the best of both worlds, though it would be a bit of a pain to do.

-daniel

danielomalley
05-16-2013, 02:12 AM
I sort of like the idea of pins, in which case I suppose the saya's fit needs to be less precise, right?

On the other hand, the pins... I guess it'd be another task producing these onself, and seems you' d need a different (harder) wood too.

For folks that like pins, I've occasionally put the pins on custom saya as well. They're pretty easy to make. If you don't have a lathe, you can just make a small piece of ebony or whatever into as close of a dowel as you can easily do. Then chuck it up in a drill press and you'll get close enough pretty easily.

Pins can be helpful over time. As the knife is sharpened over 20ish years, the saya may become loser. If so, the pin will help address this.

marc4pt0
05-16-2013, 03:33 AM
Thanks for the tutorial!

kalaeb
05-16-2013, 09:13 AM
Wow, westerns, wa's and sayas, a man of many talents. Thanks for the WIP. Makes me want to head up and see your shop.

Patatas Bravas
05-16-2013, 11:14 AM
Pins can be helpful over time. As the knife is sharpened over 20ish years, the saya may become loser. If so, the pin will help address this.

Good point! Yeah, I know people buy, sell and trade a lot, but i certainly hope mine are around in the future.

markenki
05-16-2013, 11:45 AM
Very cool! Thanks for sharing. What is the purpose of the half-circle notch? (I've seen that on some other sayas as well.)

danielomalley
05-16-2013, 12:48 PM
Very cool! Thanks for sharing. What is the purpose of the half-circle notch? (I've seen that on some other sayas as well.)

There are a few things over the years with Japanese knives that I've never been able to get an absolutely straight answer from makers about why it is done that way. Frequently Japanese makers' response to this sort of question is, "because it is the way I was taught." And I'm afraid my answer is similar.

That said, I have some speculation about the origin of the notch... because the back corner of Japanese knives is generally fully sharpened, getting poked by the corner can be less than fun. by having the notch, you're able to see where the blade starts as it is taken out of the saya before the sharpened corner reveals itself. That's the best that I've been able to come up with ... and I do think it makes getting cut while taking a knife out of a saya a bit less likely. Plus it looks good :)

-daniel

SpikeC
05-16-2013, 02:55 PM
It is used to align with the nib on old western saws.......................

stevenStefano
05-16-2013, 04:58 PM
I know sayas without pins sort of show that they are well made, but a while ago I had a knife with a saya and no pin and I dropped the knife. It never stayed in the saya again, the perfect fit was gone

danielomalley
05-16-2013, 05:37 PM
I know sayas without pins sort of show that they are well made, but a while ago I had a knife with a saya and no pin and I dropped the knife. It never stayed in the saya again, the perfect fit was gone
Did you drop the knife with the saya on it (such that the saya somehow changed shape/came loose at a seam or whatnot) or did you drop the knife, which then needed reshaping and therefore was a loose fit at that point?
If the later, this is exactly why I don't recommend using a pin initially -- if a saya becomes a little loose, the first recommendation for a better fit is to shape just a little off the flat where the knife is inserted. This will allow the knife to go in further and should bring the knife into a tighter fitting area of the saya. If it already has a pin, the pin hole will no longer be effective (and often it is only necessary to remove 1mm or so, so drilling a new pin hole looks a little odd). If going in further doesn't tighten up the saya, then the pin can be added for a proper fit and the hole can be drilled in the correct place.

For what it is worth, I do a lot of adjusting our 'stock' saya to fit knives well when people don't want the expense of a custom saya. It is amazing how much adjustment can be done by shaving off a little from the area the knife is inserted and by using kiridashi and rasps to widen the hole slightly where the knife is inserted. Naturally, the fit won't generally be as perfect as a custom saya, so I still recommend a pin at that point, but it is amazing how many a good fit can be matched by making those adjustments.

-daniel

pkjames
05-16-2013, 06:39 PM
Stunning stuff! Tks for th tutorial!

stevenStefano
05-16-2013, 07:02 PM
It fell while not in the saya. I understand what you say, that is interesting, thanks