Straight-Line Guide for the Router
This router guide, when used with a top-bearing-guided pattern-maker’s bit, turns your router into a jointer and a precise trimmer. An embedded aluminum bar makes this jig more accurate and durable than others like it.
To make it, cut a piece of 1/2-in. birch plywood about 4 in. wide (half the diameter of the router’s base plus 1 in.) by 4 ft. long. Rip a piece of 1/8-in. hardboard 1/8 in. wider than the plywood for the guide’s base. Now cut a 4-ft.-long piece of 1-in.-wide, 1/8-in.-thick aluminum bar (grainger.com). Clamp the bar about 1/16 in. proud of the plywood’s edge and then rip a piece of 1/8-in. hardboard to fill the space behind the aluminum. Glue this filler to the plywood. Now assemble the guide with 3/4-in. screws. Finally, with the router bit’s bearing on the aluminum, make one full pass to establish the reference edge on the exposed hardboard. Your guide is complete.
To use, just clamp the guide to the workpiece with the lower edge aligned with your layout marks. Set the router depth so the bit’s bearing is on the aluminum edge and trim away. Be sure the guide is clamped securely at two points at all times. Also, don’t let the router tip.