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When making molds, it always bothers me when I wind up with those guitar shaped cutouts. It just feels so wasteful. I don't need bending forms (I bend by hand). I know I can cut them up and use them for cauls and what-not, but it still bugs me to use that much plywood. Before doing what I outline below, I was using almost half a sheet of plywood to make a regular sized mold: 8 pieces of ¾" plywood, each 24" long, 10" wide, all bandsawn and pattern-routed to the proper shape. This yields 8 guitar cutouts that I have to find uses for.

This time around, I decided to just cut 4 of the ¾" x 24" x 10" pieces, bandsaw and route them to size, and use those as the outside layers of the mold. For the inside layers, I used the guitar shaped cutouts, bandsawn into blocks, glued to the outside layers, then bandsawn and routed again to match the outside layers, then glued together to make the 4 layers per side. Like this:







This wound up only requiring a quarter sheet of plywood for one mold. Here is the final product:



There are a few small gaps on the inside layers, but they don't cause any problems.

I feel much better about making this mold with half as much plywood, and plan to do it this way from now on.

Cool--I keep a box full of baltic birch cutoffs that might be small, but too good to waste. Next time I'm mold making, I'll keep your idea in mind!

Dave

Clever!

I have a mold with top and bottom of 1/2" ply w/ construction grade 2X pieces glued in between. Lots of spaces between them. Works as good as my solid ones.

Great idea! Even though I've used a bunch of the cutout pieces from previous molds for cauls and jigs/fixtures, I still have a box full of them left over (I have a hard time throwing out scrap wood, just in case...). Now I have a use for a bunch of them. Thanks.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Hey Don,
I'll join the club! A lot of my molds started out from scrap - not as many small pieces, but I make up for it with "gaps". Even though we are working wood it's nice to save a few trees along the way. Yours still look first rate, mine would win the ugly dog award, but they still work.

I have just used some 2x2 cedar scraps. works fine and lighter weight. Doesn't even need to be solid all the way around. I was experimenting with MDF on this but I think I would use plywood in the future. The MDF has more give than I want, although the second picture with MDF core is fine.

Pat

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Pat

Can't imagine what happened to my previous post on this thread... Anyway, it's a good idea and one I heartily approve of. As a former tool & die maker, I can tell you while it seems like more work, sometimes it just makes sense and might even be necessary. A multipiece tool will work just as well as a single piece in most cases. And less waste is a good goal to have. I don't see how anyone could make a good argument against it. DRIVE ON!

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"Act your age, not your shoe size" - Prince

Amateur her, having built 9. All of my molds have been out of 1/4 sheet of 3/4" plywood with 2X4 scraps from a construction dumpster as separators. I have not spent too much time making the center pieces exactly the right shape and the sides end up contacted the edges of the plywood only for most of it. I bend sides on a pipe and have great success in having them turn out flat on a completed rim. As has been said, I use the center cut-outs for jigs and fixtures, but this has me thinking about that.

It was definitely more work than just cutting and routing 8 layers, and I normally try to do less work if I can, but in this instance, my desire to conserve material overrode my desire to conserve effort.

I found that bandsawing the cutouts into strips about 2.25” wide, and then from those strips bandsawing blocks with varying angles on the ends, worked pretty well. I wound up also needing some of the 24” x 8” board left over from cutting the 4 24” x 10” outside layers. But there were some useful scraps at the end, and it all came from a single 48” x 24” piece of plywood.

That's a winner, for sure. Good thinking.

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George :-)

Excellent!