A large bridle joint requires an open-ended mortise that may be too deep to cut with a 10″ tablesaw. I encountered this problem when I used my saw to make bridle joints on an exterior door. I tried to finish the cuts on the bandsaw, but was unsatisfied with the results: Working freehand left mortises with uneven bottoms. So, I made a fixture to guide the cut. It uses a pair of drawer slides to move a platform side to side on my bandsaw’s table.
The fixture has two parts: a base that’s clamped to the bandsaw’s table and a moving platform. I mounted two drawer slides to the base; their mating pieces are mounted to the underside of the platform. A cleat mounted to the base’s underside registers the fixture square to the blade. I marked parallel lines on the platform to make sure the workpiece was positioned square to the blade.
Removing only 1/64″ at a time, I can deepen an open-ended mortise by moving the work piece back and forth on the slides. After several passes I get the depth I need, and my mortise has square corners and a flat bottom. -Mark Thiel