...I was wondering what the traditional knife saya construction is/was....
Way to verbose responses you got here.
Traditional saya, is two piece saya, with cavity carved on one side. Three piece saya was "pioneered" by TC Blades a few years back and since copied by a few.
Here is how I make my (traditional) sayas.
Tools needed:
-Bandsaw (if you resaw your wood)
- 6x48 disk/belt sand for squaring, flattening, and shaping
-Piece of marble top with sandpaper glued on for flattening halves for precise fit
- Bench Wise for holding a half where cavity is carved out
- Saya chisel/s- very important, will save you time. Other chisels don't work well. If you can't afford 2, get one in 3/8. Buy 5/8 at a later time. They are $150 at JWW, but you can buy it on 10% sale.
- Clamps or you can tightly wrap your halves with electrical tape. It will work.
Use poplar, cedar or straight grain redwood - soft woods, as woods like maple and even walnut are difficult to carve, and the more figure in the grain, the more difficult to carve.
Resaw the board, give it 24 hours to rest for working out the tension, then flatten. Secure the half for cavity in your bench wise. Make an outline of you knife with a pencil, and trace the outline with a cutter, making a 1/16 or so cut into the wood. Then with a 3/8 saya nomi tilted so you are cutting just with the corner of a chisel, carve the perimeter of the cavity, and then remove the wood in the middle. Important that you establish the direction of the grain and carve
with the grain. You will feel that in one direction your chisel struggles a bit, and in another it doesn't - that' the direction. Also when you carve with the direction of the grain, you carve tip to heel, so you can apply a little more pressure and remove more material toward the heel, similarly to knife's geometry. Here flexing of saya nomi is invaluable. Careful not to run over your cavity perimeter. Fit your knife regularly, tilt the cavity half to the light to see the depth of carving , so you see where you have high points. Mark them with pencil and remove them. There is a little bit of a learning curve, but I would say, after carving 4-5 cavities, you will have a good idea.
Gluing. The reason you carve on one side is because wood will shift when glue is applied and you clam it, and aligning two carved cavities would be difficult as you have a small window of time and glue bonds fast. Apply glue on one side (cavity side), carefully align both sides, carefully fasten them with electric tap. Once you see that everything is aligned, wrap tightly with more tape. You can clamp over it or leave it just with a wrap (it has to be tight though).
Notice I don't give halves the shape of knife before hand. I need them to be stay rectangular to be able to to hold them in a vise and clamps.
Mark the location of the cavity on the outside with calipers, you know where cavity is after you glue the halves up. Put a knife over caliper marks, outline it, add some extra, and rough cut with a band saw. Then give the final shape with a sander.
Shaping is best done on a sander of sorts. 6x48 belt/disk is probably your best option.
You can be creative - give a saya distal taper, cut bevels and chamfers on the spine and then blend them by hand (cork block with coarse 80-100 paper works well). Finish saya to 320 grit by hand, best outdoors on a sunny day, so you see scratches better.
For finish, apply tung oil, let it soak a 10 min, remove excess and let oil cure for a couple of days.
Done.
PS: once you master softwoods, you can move onto hardwoods and highly figured woods. If done properly, you won't see a glue joint, so your saya will appear as one piece. I think it is worth to put in time and effort to learn this method over a shortcut.