Can plywood be used to create signs and any projects and if so what is the best plywood to use. I am still learning about CNC but want to create larger signs out of one piece. I am currently gluing but I would like to try to create on one solid single piece.
Plywood can be used but the quality of the plywood is important. Regular plywood has voids under the nice skin. If your cut into the voids it can be quite visible in the finished project. Baltic Birth is not supposed to have voids but you never know until you cut through.
Another consideration of cutting through plywood is the plywood layer depth. I would suggest you try to match the depths of the plys to keep from having carvings that are just on the boundry of two ply layers. Additionally as I said above some plywood inner layers have voids and are not always perfectly flat making the appearance of your carving look different in different places. If you are going to paint the v carving then that would be not as much of a problem.
In general I do not use plywood much because of the reasons above. A lot of things just look better to me if they are carved in solid wood. There is definitely a place for plywood but always do a test run to see if the look will be good when finished. Plus since the top layer is so thin you tend to get a lot of fuzz and splintering on plywood so down cut bits may be best. Up cut bits would exacerbate the splintering.
I agree with everything Guy said and will add a few items. I use a fair amount of plywood on my CNC machine, some of the projects are attached.
I like plywood for templates and jigs among other things, structurally, molecularly more stable in dimension than “pure wood.”
These are all 1/4" plywood of various grades, all cutoffs from other projects. It seems every manufacturer as well as every sheet tends to have its own personality. I tend to put masking tape, not painters’ tape, over the tool path to reduce the splintering on the up cut tools paths when smoothness of the edge is critical. It helps, does not cure the issue.
I tend to go for exterior glue plywood - AAX, ABX etc. You will find differences in glues as they get milled. Some will really gunk up your cutters, others cut very cleaning - speaking only of residue on the cutters. Heads up, glues between manufacturers and even productions are not consistent.
As for travel speed, I tend to slow the default down a bit using the 10% increments of Carbide Motion and watch how it is going. Finding knots in the inner plies is a bit tough on the machine.
And you need to precisely measure the thickness of just about every sheet. In these projects there are numerous different source sheets, some A-A, some A-B, some A-C, some interior, some exterior. As stated, all just pieces sitting in the shop to the point I wanted them gone. And they measured from 0.19-0.24 inches in thickness.
Before purchasing, check the thickness of the face veneer. Face and backs are most likely different even on AA sheets. On some of these bunnies and hearts, the veneer is so thin I would have been a bit hesitant about even sanding them if I was finishing them with a stain or clear coat.
A 1/2" plywood project.
Good luck with it,
plywood works, baltic birch and other higher grades give better results.
Also assume that your bits will get dull a bit quicker on plywood; I tend to use my slightly worn bits on it rather than spanking new ones
V carving on plywood gives me a more mixed result at times depending on the quality of the plywood, it may splinter more than you like.
Great post! I hadn’t considered the types or grades of plywood to be relevant to cutting, awesome info here!
What is the smallest end mill you think would work without incident/breakage in plywood? 1/16"? 1/32"?
I have used 2mm (0.079") without issues (baltic birch grade). But usually I make sure to do a roughing pass with at least 1/8" so that the smaller bits only do the remainder
Oh ok, I was thinking more in terms of doing detail work with a ball cutter, almost like inlays… I will just have to try it out and see.
one thing to remember is that the best looking part of plywood is generally the top… what’s inside is … more of a mix… higher grade is better for sure though.
I use quite a bit of plywood for furniture-type projects, and find that the quality is the biggest factor. Big Box store plywood generally has a lot of voids in it, along with filler used in the veneer faces. its fine for structural stuff but the finish isn’t that nice.
Then you have the quality stuff that’s really nice, I bought some plywood specific to laser cutting and the finish was stunning on it, and because the glue was designed to be lasercut it didn’t hammer the cutter as much as box store stuff. Obviously that comes ata premium in price but it wasn’t crazy
Another “tell” on plywood is to look at the edges for gaps. Look closely, because sometimes they are filled in by the edge cutting process.
If you see a gap on one edge, you can follow across to the opposite edge and find the other end of it. There’s going to be missing wood all the way across. Your cut will find it in many places, and if you try to fill it in, you’ll be filling in the whole width like a cavern in the ground.
I wouldn’t necessarily dismiss that sheet, but make sure you can work around it in your project.