
There is a block inside that is radiused to the top. Two 3/16 bolts pass thru the locating pin holes, and tighten with wing nuts. The two screws on the end have a nut inset into the bottom of the clamping caul, and bear on small hardwood blocks to clamp the wings down. This is also a more or less single type of guitar jig, but it's easy to make, so I'll just make more as I go along.