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How to Cut a Perfect Jig Circle

Ask This Old House host Kevin O’Connor works with House One maker Jenn Largesse to demonstrate an interesting technique on a trim router.

Steps for Cutting a Perfect Circle:

  1. Before doing any work to the router, be sure that the battery has been removed or the router has been unplugged.
  2. Remove the base of the router by unscrewing it by hand or with a drill driver.
  3. Place the router base on the ¼-inch board and trace the screw holes and the opening for the bit onto the board.
  4. Drill holes in the locations of the screw holes using a countersink bit. The countersink bit will ensure the screws can sit flush with the base of the router, which will be important for cutting.
  5. For the center hole, drill it out using a spade bit.
  6. Determine the desired radius of the circle and then transfer that measurement to the board. Use the center of router bit hole as your starting point.
  7. Drill a small hole at the measurement of the radius. This will eventually accept a nail and will act as a pivot point.
  8. Attach the board to the router in place of the base. The screws and screw holes should all line up with the ones drilled in the board.
  9. Secure the board being cut to the work surface with clamps or screws.
  10. Determine the center of the board being cut by measuring diagonally from corner to corner. The intersection of the two lines is the center.
  11. Place the router with the jig onto the board. Line the nail from the pivot point up with the center of the board and hammer it into the board. Be sure to not secure it too tightly, as you will still need the router to move easily.
  12. Set the router bit just slightly past the depth of the jig.
  13. Turn the router on and start cutting the board. Turn the jig at the pivot point as you cut. This will create a circle.
  14. After the first pass, lower the router bit again and make a second pass.
  15. Continue this process until the circle has been cut.


Jenn demonstrated how to cut a perfect circle using a RYOBI ONE+ cordless trim router manufactured by Ryobi Tools.

Jenn Largesse is the editor of multiple DIY blogs, including House One and Build Basic.

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