Recently, I needed to cut a large number of 5/8-in. grooves across several large pieces. Because I dislike using cutters larger than 1/2 in. in my small router and because I wanted to minimize the number of router-fence setups, I quickly designed and cut the asymmetrical router-base plate shown in the drawing.

The theory is quite simple. Simply vary the base’s offset by the amount you want to enlarge the groove, In my case, I wanted to enlarge the 1/2-in. groove to 5/8 in. So I cut the base 3-1/2 in. from the center of the bit on one side and 3-5/8 in. on the other, a difference of 1/8 in.

To use the fixture, set a fence parallel to the line of cut, make one pass with the first edge against the fence, and then make another pass with the second edge against the fence. One setup, two passes, one odd-size cut.

Alien Trivino, Rochester, N.Y.

Fine Woodworking Magazine, April 1992 No. 93

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