When assembling trim or cabinets, I often need to clamp 135° mitered corners together for gluing. Bar clamps alone don’t work because the compressive force from the clamps needs to be in a line through the center and perpendicular to the mating surfaces being glued. In this situation, I use clamping jigs made from scrap plywood to apply all the pressure needed without having the clamps slip off. As shown in the drawing, the trick is to lay out the joints’ cross-sectional profile so that the two halves of the jig accomplish both the in-line and perpendicular requirements. Knowing the throat dimension of the clamp is key to designing the jigs so that the line of pressure passes through the joint.
Nils Omholt, Sterling Heights, MI
Edited and Illustrated by Charles Miller
From Fine Homebuilding #193