I recently had to rout a series of dadoes slightly wider than the router bit into some large panels. To accomplish this, I took advantage of my slightly eccentric router base. In relation to the collet, most router bases are less than perfectly centered.

Through trial and error, using pieces of scrap, I determined the high spot (the one farthest from the collet) and the low spot (the one nearest to the collet) on the base. I marked these locations with masking tape. I also marked several intermediate locations between high and low.

With a fence clamped in place, I made a single pass, keeping the low spot against the fence. Then I rotated the router base, placing the high spot against the fence, and made a second pass to enlarge the original dado slightly. The second pass added about 1/32 in. of width to the dado just the right amount for my application. If your router base is one of the few that happens to be concentric, you can accomplish the same effect by adding layers of tape as shims on the outside edge of your router base.

Scott Bowen, Salt Lake City, Utah

Fine Woodworking Magazine, April 1998 No. 129

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