Recently, I had to rout lots of dadoes in cabinet sides for 3/4-in. plywood shelving. I came up with a method built around a 5/8-in. patternmaking router bit (with the bearing located above the bit) and a simple jig made from two pieces of l-in.-thick plywood about 6 in. wide. The two pieces of plywood are joined by a small piece of 1/4-in. plywood at one end that pivots.

To use the fixture, clamp one side to the cabinet side along the index line you have drawn for the shelf location. Position an offcut of the same material you will be using for the shelf between the two parts of the jig. Swing the second fence toward the first fence so that it sandwiches the offcut, and clamp it in place. Now remove the offcut, and rout the dado, running the bit’s bearing against the sides of the jig’s arms.

This system is more accurate than any other method I’ve used. It even adjusts for minor variations in sheet thickness.

Robert R. Knights, Woombye, Australia

Fine Woodworking Magazine, June 1997 No. 124

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