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For a uke I'm making, I bought birch plywood to use for the back joint strip (for the inside support). I know that the grain on the back strips should go across and perpendicular to the joint. So I cut the 1/2 " pieces and went to shape them with the sander, and found that the plywood appears to be running WITH the direction of the strip even though the outer grain appearance made it look like I was cutting perpendicular to the grain. In the picture, the large piece is what I bought at the hobby store. The two strips are in various degrees of shaping the edges and you can see the plywood layers. Do these strips, once shaped, qualify as cross-grain supports? I got the birch plywood because that was specifically recommended in one of the references I found, but have also seen basswood, spruce and cedar mentioned (and the grain on those would be obvious). Don't want to pitch this wood if I can safely use it, but if it won't support properly, I'll use one of the others above.

Thanks for the input. Hope the picture turns out okay. Beth

It's plywood so each layer (Ply) alternates the grain 90 degrees. Can't say much about using it but imagine on a small Ukeulele you're not going to see lots of movement of the back so it may not matter. Hope someone with Uke experience chimes in. I've not heard of it being used except for backs/sides/tops on less expensive imports.

Thanks Mark,
Makes perfect sense. I think since I'm making a nice Koa uke, I'll use the cedar back strips you can get at a luthier supply...it will obviously look better too. Have a great weekend! Beth

Beth, I would save that plywood for heal blocks( great for that) and use spruce or some solid wood on the center back joint.

Thanks Mark! I'll do that. Beth