MIMF

I'm going to make some cam clamps.
What's the best wood to use?
I'm concerned about it splitting.
Thank you,
Mike

I used birch on some back in 1975 and they are still good. Recently I built 50 cam clamps for gluing top and backs to the sides. I bought a bunch of 1/4” Baltic Birch plywood and built the clamps up in layers so I wouldn’t have to cut the mortises. It worked out well.

I've built cam clamps out of maple, cherry, walnut, birch, and baltic birch plywood. The only ones that split had something wrong with the design, not the wood. And I think I only had one or two split.

-Eric

In a batch of a dozen lightweight clamps made of poplar, one has split. And it turned out that had tiny inclusion hidden in the wood. The poplar (aspen, not tulip poplar) was what was on hand. If I were making more, I'd probably go with a plywood.

Barry Daniels wrote: ↑Tue Jan 09, 2024 9:49 am I bought a bunch of 1/4” Baltic Birch plywood and built the clamps up in layers so I wouldn’t have to cut the mortises. It worked out well.

That's a good idea, I'll do that when I need more.

-Eric

Thank you.
I like the idea of laminating 1/4" pieces.
Mortising 10+ holes is not something I'd want to do.

Barry, can you post a picture of one of the laminated clamps, seems like a really nifty idea, keen on seeing how you did it.

I made it fairly short. Just long enough to reach over a body form to clamp a top or back to the sides. All is made from 1/4” ply except the little flapper is made from 1/8” Baltic birch. The black dots are steel roll pins that get driven in.

One additional detail is the 1/4” ply is actually metric and a bit smaller than 1/4”. This made the mortise too thin for the 1/4” aluminum bar. So I added pieces of veneer to get the required width.

One more thing. The aluminum bar stock was too slippery and did not grip the mortise until I hit the back of the bar with a 60 grit sanding disc.

Thanks Barry!
So you've made the bar from aluminium, that makes sense. I hear you on the bar being too slippery, recently bought a bunch of clamps from Bessey, 150mm, but they all slip because the bar is too slippery, there is a sort of knurling on the back, but the plating process rounded that over too much, so I need to go over it with a triangular file, bit of a pain.
Simple enough design, keen on giving this a try myself, the thinner ply I can get here is pretty lousy though, so I think I would go for 12mm/15mm birch ply (1/2" / 5/8"-ish), and then maybe also make the bar out of the same material.

That would be an excessively thick and bulky clamp. My clamp design is made up of three layers of the plywood. I would not use normal plywood for this. You need something with zero voids and made from quality hardwoods. If good plywood is not available you would be better off using solid hardwood or three layers of solid hardwood laminated together.

Do agree that it is going to be wide, but then again, you don't want to put excessive force on a concentrated spot, spreading this over a larger area makes sense with fragile components. Then again, not sure how much force these clamps are generating, probably a lot less than a good old C-clamp
Found a source for 9mm birch ply which looks interesting, slightly less bulky

Sorry but that rational for a wider clamp doesn’t hold water. Spreading out the force is easily done with a caul. Also, I have a 1” wide pad attached to the clamp which spreads the pressure. My clamps are fairly weak compared to a metal C-clamp but still provide sufficient pressure for my needs.