How would you make this?

[Wilbur Harris]

Hi Folks - new guy here! Don't currently own any tools or contraptions but have an interest in making knife sayas for myself and perhaps others. The ideal saya fits a knife blade closely while not "pinching the blade anywhere. That criteria doesn't allow making generic sayas given the difference in knife blades from knife to knife. In other words...trace the knife blade and make a saya. Cost is an object as I don't have unlimited funds but consider that I do. I'm thinking a laser or CNC router but hardly know enough about either to ask proper questions.

Here are some pics:

260379260380260381

How would you do it?

[Joe Hillmann]

They could be very easly made out of three thin pieces of wood or plywood with a laser or cnc. I would first trace the shape of the blade on a piece of paper, scan it into the computer then trace the scan in coreldraw. Then cut it on the laser.

With that said since each knife is different it would take about the same amount of time to cut it out on a bandsaw or scroll saw. You can buy a cheap band or scroll saw new for less then $80 that would do what you want or buy better quality second hand tools for a bit more. I would also suggest getting a benchtop belt sander to round the edges on.

If you go with the laser cut method, first you need a laser, which can cost as little as 2 or 3 grand up to 30-40 grand. Then you also need coreldraw which cost $500 give or take (you can find used coppies for as little as $100). You also need a ventilation system and maybe an air compressor for air assist.

I don't own a cnc so maybe someone else can help you there.

With both the laser and CNC you need a computer to run them.

If making sayas is your only plan for a laser/ CNC I think it is a bad idea. You could make them just as fast or faster with a much much smaller investment in more traditional woodworking tools.

[Joe Hillmann]

After a little bit of thinking. To make the nicest possible Sayas I would get a bandsaw, router, and abench belt/disk sander (searching Craigslist today I could get all three of those items for less then $150 combined).

Take your block of wood cut it into a rectangle about 1/2" wider and longer then the knife blade.

Use the bandsaw to resaw the block of wood to about 4 or 5 times the thickness of the blade. This is now your blank

Use the bandsaw to resaw your blank again so you have two pieces one piece being 2/3 of the blank and the other being 1/3. Set aside the 1/3 piece.

Trace the blade shape onto the 2/3 piece of your blank.

Use the router to remove 1/2 the thickness of the 2/3 piece inside of your traced line. Take your time and slowly work your way towards the line.

Glue the 1/3 piece back onto the 2/3 piece. Make sure to glue it back the same way you cut it off so the grain lines up. To get a nice clean glue line you may have to run both faces on the belt sander.

Once the glue drys trace the knife blade on the outside of the saya. Trace another line about 1/4" out from the first line.

Use the bandsaw to cut on the outside traced line.

Use the use the belt/disk sander to smooth out your saw cuts.

Use the router round the edges of the saya or use the sander to shape and round the edges of it.

Drill the hole for the saya pin.

Sand the saya by hand until it is as smooth as you want.

Varnish it. Sand again. Varnish. Sand.

Now you should have a finished saya.


I know the way I explained it sounds like a lot of work but you could probably pop one out in a half hour (not counting drying time) If you want to speed it up even more use sanding sealer for the finish, it drys in minutes.
They could be made much easier with 1/8" plywood or bamboo but the overall product wouldn't be as nice.

Of course there are hundreds of ways to make a saya, this is just the way I would do it if I had to start with no tools and as small of a cash outlay as possible. With that said. I do own a laser but I don't think I would use it to make saya if I was making them, there are just better ways to do it.

[Wilbur Harris]

Thank you Sir! I'll mull that over and perhaps be back....:)

[Wilbur Harris]

Can a laser cut out the slot for the knife - cut deeper for the spine and then gradually shallower for the edge ( a gradient if you will)?

I was thinking that I could lay out the job to hollow the knife cavity (half on one side and half on the other), cut holes for locater dowels to make it simple to assemble, and then cut out each half. My concern is whether or not the laser can do the blade cavity properly.

Don't know why this ended up in the metalworking forum but the moderators know best.

[Dan Hintz]

I'll take Joe's process in a slightly different direction (I think)...

Scan the blade directly on a flatbed scanner. Using your favorite drawing program (CorelDraw or similar is best), bump the outline outwards 1/16". Create a 1/8" thick "spline" surrounding the top/bottom edges of the blade (leaving the back/hilt) open. Cut this spline out of wood veneer slightly thicker than the blade. Glue this spline between two pieces of appropriate wood and cut to the shape of the spline. Drill holes and you're done.

[Joe Hillmann]

If the wood is consistent you can use a laser to cut the pocket out as you describe, deeper at the hilt and narrower at the shallow end.

Although often when cutting deep into wood the bottom of the cut isn't smooth. The soft summer grain blasts away easier than the hard winter grain which causes a ripples on the bottom of the cut following the grain. Some woods are better than others. Woods like pople (poplar in areas outside of Wisconsin) and basswood have almost no grain so they should engrave with a flatter bottom than woods with lots of grain like oak and hickory.


Using the method you described after you got the shape of the blade into the computer using my method or Dan's or some method you come up with I would take two rectangular blanks of wood about 3/16 (maybe 1/4) that are large enough to make the saya out of. And on one using the laser cut out half the pocket for the knife blade, then cut the outline of the saya and two or three alignment holes for pins. And then cut out a mirror image of the first onto the second blank.

To assemble it all you would have to do is maybe a little bit of sanding on the pockets where the blade goes then glue them together with pins in the alignment holes. Once it is glued together it is up to you to figure out how you want to finish the outside.

With my 55 watt laser I cut 5/16 maple and the edge is brown but nice and smooth and I am able to cut quite a bit of detail into it without charring.

Although I still think there are other tools that would be better/faster/cheaper at making saya but that is up to you. If you really do want to go the laser route I would suggest finding someone near by with a laser and see if they can help you do a bit of testing that way you will know what you are getting into.

As far as it being moved to the metal working forum, I assume that the mod thought you were asking on how to make the knife rather than the saya. If you have other questions don't be afraid to come back to the laser forum and ask, the people there can be very helpful in sharing there experience.

[Dan Hintz]

Cut this spline out of wood veneer slightly thicker than the blade using a laser.

Meant to add in that little bit when I first wrote it... a thin piece of wood will cut quite fast with a laser.

[John Salitsky]

I would think routing out the spot for the blade with a laser would take a long time and could be accomplished much quicker with a router although would take practice if you're not handy with one.

[Martin Boekers]

You may want to repost this in the woodworkers forum here at SMC as someone may be doing that already and can give you their insite.

[Wilbur Harris]

I have gained access to a Trotec laser used primarily to make plastic signs. The fellow that runs the laser is not of the "inquisitive" type and that's all he knows how to do - make signs. Would somebody bite the bullet and create a simplistic file that will work on the Trotec and illustrate the "deep to shallow" gradient capability on a piece of wood. I fear that I'm asking too much as I don't know the extent of such a request. If that is the case just ignore me and I'll go away. Once I see that the laser will do what I want, I'll learn how to make the file.

[Dan Hintz]

Wilber,

There's another thread talking about 3D files in the Engraver's forum... there are several good example bitmaps you can use as a test.

[Joe Hillmann]

Give this a try. You need at least Corel 11. Anything older than that doesn't allow the gradient color fill. This is just meant to be a test and will require some fine tuning to get the gradient right.


261625


The area for the knife cut out starts at 50% black and ends at 10% and has the midpoint at 60% (from the top) and a 377degree angle. In theory the back of the knife at the hilt should engrave deapest, getting slightly shallower as it gets towards the point and also getting shallower much quicker as it gets towards the cutting edge.

[Wilbur Harris]

Thanks a Million !!

Now, if the guy that runs the laser can figure out how to run this generously offered material I'll be all set. Well...partially set anyways.

I really do appreciate Y'all taking the time to help me out.