How to Make an Oval Jig for a Router

Drill a series of evenly spaced holes into the piece of hardwood. It should be at least 3/8 inch thick, about 2 inches wide and as long as necessary for your ovals. This will serve as the arm of the jig. This is an adaptable plan, so you can build to suit.

Cut a piece of the 6mm MDF (medium-density fiberboard) so it is a little larger than the base of the router. Drill a hole in the center for the router bit to pass through. Also drill holes so you can drive screws through the MDF into the base to keep the router attached. Also attach a piece of 3/4-inch stock to the base plate to use to attach the swing arm.

Attach the pivot arm with two screws driven through the arm and into the 3/4-inch stock on the MDF base.

Cut a circle from another piece of the MDF. This will be the bottom piece of the pivot base. It can be approximately 12 inches in diameter but once again can vary according to your plans.

Find the center of the circle and draw two intersecting lines through the center point They should create four 90 degree angles.

Attach the four top pieces of the pivot base with wood glue. Start by intersecting the circle with a thickness spacer and then intersecting each half-circle with another thickness spacer. The result should be four equally sized squares laid over the circle with equal spacing between them. Once the glue has dried, trim the top blocks with a jigsaw to match the MDF circle.

Cut two sliding pivot blocks out of the hardwood. Drill hole to accommodate and countersink one bolt in each of the blocks. These should be at least 3/4 inch wide to avoid splitting.

Attach the pivot blocks to the pivot arm. Start by sliding the bolt through the hole drilled on the pivot arm. Then slide a washer and a wing nut over the bolt and tighten. Do not over tighten to the point where the arm does not pivot though. Repeat this process for both pivot blocks.

Slide the pivot blocks into the channels of the pivot base, and start routing your ovals.