Although I’ve seen dozens of methods for routing circles over forty years of woodworking, the method I stumbled on early is still the least complicated and quickest I’ve seen.

Two small hardwood blocks kept right in the router storage case are the heart of the method. The blocks slip on your router’s guide bars leaving a bit of the bar exposed, as shown in the sketch above. When the blocks are in position, the distance between them should be 1-5/8 in., the thickness of a 2×4, so that any length ripped from a 2×4 can be used to size the radius of the circle to be cut.

To cut the circle, drill a 1/4-in. pilot hole in the 2×4, and use a dowel or 1/4-in. bolt on a block as a pivot. Or just drive a nail through the 2×4 if the hole won’t show. Adjust the router so the bit is in position; then clamp the 2×4 between the blocks and the guide bars with a C-clamp. The open holes in the blocks allow the pads on the C-clamp to pull up tight on the guide bars with- out slipping off. With this system, you can rout circles as small as 6 in. to as large as…now let’s see, what’s the length of a 2×4 ?

Tim Hanson, Indianapolis, Ind.

Fine Woodworking Magazine, December 1993 No. 103