By replacing the footplate of the router with a board, and inserting a pivot point (I used a nail) a router can cut almost any size circular cut. Some woodworkers even prefer this method for cutting round dining tables If you’re going to be using this jig a lot and want to make it reusable, it may benefit you to make it out of a thin sheet of acrylic and drill a series of holes with standard spacing. I may do that in the future, but for testing out the process with these small projects, a piece of wood worked perfectly. To get a feel for this process, I tested it on three small projects; a stool, charcuterie board, and a round mirror frame. Read on to see how to make your own!
How to Make a DIY Circle Jig:
Step 1: Remove the router footplate To get started, remove the battery (or unplug) the router. Unscrew the screws that hold the footplate on the router, and then remove the footplate. Step 2: Trace the footplate onto a board Trace the holes onto one end of a long, thin board like a ½-inch-thick board you can easily find at the home center. Step 3: Drill the holes Drill holes for the screws and the opening for the router bit. Flip the board over and countersink the holes for the screws so they set flush with the bottom of the board. Step 4: Attach the board to the router Using a drill/driver, attach the board to the router using the screws and holes used by the footplate. Step 5: Adjust the router bit depth Fit the router with a straight bit. Set the depth of the first pass to less than 1/8-inch. Step 6: Set the pivot point Mark and drill a small hole in the board for a pivot point at the desired radius of the circle. Step 7: Make the circular cuts To get ready to make a cut, clamp a piece of plywood to the work surface. Lay the board on the plywood and screw it in place at the corners. (On my first take I only screwed in two corners, but opted for all four corners on the next rounds.) Hovered the router over the wood, and then plunge into the cut, pivoting the router around the circle one time. Shut off the router and vacuum the path clean. Set the depth of the router bit down another 1/8-inch and repeated the process until you cut through the full depth of the board and are left with a perfectly circular cut.
Step 8: Stool Project - Cut the legs To make the stool, I repeated this cut on a second board to double the thickness of the seat. I then cut four legs at 15-degree angles on my miter saw. As a tip, I marked the front edge of the angled cut (and used a stop block) so I knew exactly where to line up the angle on the underside of the stool facing inward toward the centerpoint. Step 9: Stool Project - Mark the seat Pre-drilled holes in the stool seat at 1¾-inches from the edge using the angle of the leg as a guide, and into the center of each leg. Step 10: Stool Project - Attach the legs Apply a small amount of glue to the top of each leg, and then drive screws through the seat and into each leg. Step 11: Stool Project - Secure the seat Lastly, apply wood glue to the surface of the seat and add the second layer to create the thicker top and hide the leg fasteners. Step 12: Charcuterie Project - Assemble and cut the pieces To make the charcuterie board, assemble two pine boards and one piece of walnut with glue and pocket hole screws. Mark the location and shape of the handle on the board. Hove the router and jig over the cut and mark the starting and stopping point on the board. Step 13: Charcuterie Project - Cut the handle Once the circle cut is complete, cut the shape of the handle with a jigsaw, and drill a hole for a hanging strap. Step 14: Mirror Frame Project - Cut the inside edge The last project I tried was a circular mirror frame. This project requires a cut to make the inside AND outside edge of the frame, so screw the boards to the work surface at the corners and center. Make the first cut slightly smaller than the round mirror. Next, create a slightly wider cut that fits the size of the mirror, but at only a 1/8-inch depth to create a shoulder for the mirror to set into the frame without falling through. Step 15: Mirror Frame Project - Cut the inside edge Lastly, cut the outside edge of the frame an inch and a quarter from the inside edge. Once the pieces are ready, apply glue to the ends and lightly clamped them together. Finish the frame and use glue to attach the mirror to the shoulder from the backside.