Introduction: The Simplest Circle Cutting Jig With a Plunge Router

About: I am an electronic artist living in Upstate New York. I work with LEDs, microcontrollers, and analog electronics to create objects that I find beautiful.

If you have a router with plunge base, you can use it to cut circles without a special jig. Even though the diameter of the circle you can cut is quite limited, this would be a neat trick to know.

I happen to have a Makita trim router with plunge base, but most router should work the same way.

You need;

  • A Plunge router
  • A long screw that is the same size your router's template guide screw - longer than the material you are about to cut (Mine is 5mm Metric screw, and I used a 30mm long bolt)
  • A plastic or wood to use as a support - need to be longer than the diameter of the cut
  • Some double sided adhesive tape

That's it!

Step 1: Prepare Your Material

First, mark the center of the circle you want to cut. Then drill a hole for the center screw to go through.

If you are making a complete circle, you need to attach a support from the back, so that your center point would not move when you complete the cut. (Might sounds obvious, but I only realized that by trying a first cut!)

Step 2: Attach the Router and Start Cutting

Secure your material to a stand or some suitable surface, and attached the router to the screw. Make sure that screw is not too tight and you can rotate the router freely a full circle.

Unless you are cutting something very thin, you would make a few paths to complete the cut. Stop after each path and clean up the debris.

If you used plastic sheet as the support, you should make sure not to go too deep past the material.

For my Makita router, the diameter of the cut (hole size) can be between about 3 to 3.5 inch. The hole size depends on the routing bit diameter - larger bit makes the hole larger.