TM Stock
For really thin stuff, such as the usual 1/8" to 3/16" stock that luthiers work with for plates, even opposing clamps will not work that well for maintaining a flat panel, so a combination of the tape method and the wedged 'Cumpiano' method (from Cumpiano & Natelson's 'Guitarmaking') is used.

- Joint and dry-clamp the panel show face up into a fixture made with some 3/4" ply, a 3/4" fence screwed to one edge, and the wedge/wedge blocks seen in the photo on the other edge...a fixture 8" wider than the work and a few inches longer works well.

- Tape across the joint with 3M 1" wide stepping tape every 4-5 inches, then cover the joint along its length with some low tack masking tape to keep glue from dripping through.

- Remove the wedges, then flip the panel around face-down, use a couple small blocks to open the joint (which is now nicely hinged with tape), glue with hot hide glue in a 2 ounce poly squeeze bottle, pull the blocks to close the joint, then place a 5 lb weight on the panel face to keep things from buckling while the side wedges are inserted and lightly tensioned. Use a dead blow hammer to tap the jointed edges into alignment if needed.

- Clamp the pressure beam over the joint(s) and add wedges as shown. Set the side wedges.

- Some copier paper sliced into 2" wide strips both under and over the joint will prevent squeeze out from gluing the work to the fixture.