A while back I built a jig that would allow you to cut a circle with your router. That first generation jig was very basic and somewhat rudimentary in its design. It wasn’t very versatile either since it would only cut circles in quarter in increments. It was also somewhat complicated and time consuming to build.
Based on the popularity of the video I created of that project and the feedback I have received over the last few months, I decided to improve that original design to make a better jig that was more functional and easier to build. I drew the design up in CAD and Sketchup so I could create a template that could be used as a stencil to cut out the key components of the jig.
The template I drew up was for a DeWalt DWPXXX trim router. I also made on for a Bosch Colt. While these hole patterns are specific, you could use my template with success for about any router. You’d just have to use a simple method (described in my video) to locate your own hole pattern.
I started with a board that was 24” long by 7 1/4 wide and planed it down to 3/8” thick. Once I printed the template, I used a light coat of spray adhesive to secure the template to the blank board. The template allowed me to locate the critical center points in the areas that required drilling and milling. I used a punch to mark those areas for later.
I milled out a slot with a quarter inch uncut spiral router bit all the way through the blank running the majority of the length of the body. I followed that up by milling a pocket about 1/8” deep with a 1/2” straight cut router bit on the surface of the slot. Then I drilled a 1 1/2” hole where the router is mounted for the router bit to lower through. After that, I located my mounting holes and bored a 1/2” pocket with a forester bit and follow that up by drilling a 1/4” though the center of that pocket. The jig is now ready for mounting the router.
This jig works on the concept of a pivot pin that runs along the slot in the body of the jig. This allows the jig to be adjusted to any increment and any size circle within its capacity. The pivot pin was made by starting with a piece of 1/4-20 threaded rod and turning down one end of the rod to 1/8” on a lathe. The pivot pin is then threaded into a sliding t-nut, sent through the slot in the jig, and secured on top with a knob.
I also developed a alternative pivot pin assembly by using a sliding t-nut and a piece of 1/8” brass rod. This method can be made without the use of a lathe.
The design turned out great and is very functional. I tested both pivot pin assemblies and they each work without issues. You might want to watch by build videos of this project to see a step by step tutorial on how to build this jig. They are on this page below and also on my YouTube channel. I have also listed the tools and materials I used in this project below.
If you would like to build this jig yourself the follow the link below to download my CAD and Sketchup template. If you want me to build one for you or if you would like to buy the hardware kit (pivot pin assembly) then follow that same link to my RedneckDIY store. Good luck!
Follow this link to download the template.