Simple Setup Jigs for Lock-Miter Joints

I have used lock-miter router bits for years. But setting up the cuts for this exacting joint requires precision. The workpieces must be perfectly flat and have perfect edges, and the router table must have very good hold-downs and perfect infeed and outfeed faces. Finally, the bit’s height and protrusion from the fence must be exact, and dialing it in requires a lot of trial and error, which eats up test pieces. Infinity’s Lock Miter Master Jig greatly simplifies the setup job. The jig, which attaches to the bit with magnets, has engraved lines that help align the centerline of the bit with the workpiece’s centerline for both horizontal and vertical cuts (a video on infinitytools.com shows clearly how to do this). You still need test cuts to dial in the setup to perfection, but Infinity’s jig gets you closer from the start.

The jig comes in two sizes. The smaller one (LMM-002) works with stock between 3/8 in. and 3/4 in. thick, while the larger jig (LMM-003) is for stock 5/8 in. to 13/16 in. thick.

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