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I admire the elegance of Don's jig. As mentioned in another thread, I use a single row of cams on a piece of plywood to glue plates in my go bar deck. My jig is more in the crude-but-it-wprks category. The go bars take the place of the rubber bands. Since my cams are made of 3/4" slices of a piece of 2" dowel I found someplace, they don't need added dowels as handles. Strips of plastic package tape prevent the plates from being glued to the jig. Go bars, not shown, hold the plate halves in position. Don's jig could be set up in about 3 minutes; mine takes 5 times as long. Its advantage is that it holds somewhat warped plates in position for gluing.

_________________
Tim Allen
"Never hurry, never rest."

Clay

I was going to suggest the single screw in the base of each angle. Perhaps slightly scalloping that base so that contact is made by just the two ends would help them to stay put. You could just push each base into a roller of belt sander to remove a little material in the center of the base

Ed

Ed--

Do you think scalloping the bottom leg might have an effect on whether the vertical leg stays at 90 degrees to the workboard? I have no idea, but it is something I would want to verify before making a lot of scalloped brackets. I might be overly concerned about this, due to my experience with the Jim Williams universal mold I built some years ago. Making sure the closet pole pieces were vertical was a thing to deal with, as well as too much flexibility in the whole contraption. If I were to build one of these molds we are talking about, I would probably err on overbuilding the brackets, due to my negative view of the prior version.

Hi Ed,
I really haven't had any problems having them stay put with just the one screw. A small scallop in the middle might not hurt anything and if you found the Ls to be off 90 degrees might make it easier to adjust them back to 90 (by sanding one end or the other). So far the plywood Ls have stayed square and remained in place with a flat bottom. They were cut square on a table saw and notched with a bandsaw, but left unsanded. The roughness of the plys on the bearing surface may actually be better than a sanded surface for keeping them in place.
My jigging tends to be on the crude side - more function than form, so the refinement ends when reasonable functionality happens. I'm sure some improvements can be made and I'm not averse to adopting them. Sharing ideas on the forum can bring about improvements everyone benefits from.

Clay

How about a photo - I am about to build a mold and this might give me a way forward.

Ed

Hi Ed,
Here is a picture I took some time ago. You will notice the work board has slots cut in it because it started life as the movable spindle type that others use, but which I found to be lacking when going from one type of plantilla to another. Besides not putting the spindles exactly where I wanted them, I found the bolts and wing nuts to be a bit fiddly.
Here I am using the work board to hold the shape of an old guitar I have removed the back from to do some repair work to.
I will try to get some better pictures of the "Ls" and maybe show how the rubber solera fits into the equation.

Here are a few more pictures of the workboard. The brackets were made from 1 1/2 inch scrap so are thicker than they need to be. 3/4 inch plywood would work as well. The reason I made a removable rubber solera is because not every guitar design uses the same "doming" on the soundboard and this allows me to easily change it. The plywood brackets hold their shape and in this application may be better than solid wood brackets. I used flat head screws because they were handy, but a pan head or washer head screw might be better.