Circle Jig for Router - 5$ Basic and Easy Cutting Jig

I needed a circle jig for my Air Hose Reel Project , so I decided to make one with a scrap piece of Lexan (Plexiglass) sheet. This jig is the most basic circle jig you can make, it is simple to make but also cheap to make. I picked up this piece of Lexan from my local hardware store, this are leftovers when they cut bigger sheets and they sell them for 5$ ( Small pieces ). The one that I picked is 9" x 12" and 1/4 thick.

Material :

- Lexan Sheet (Polycarbonate) ( min 4" wide x 12" long ) (1/4 thick is the best)

Tools :

- DWP611 (Corded) or DCW600 (Cordless) or any Compact Router

- Pilot Point Drill Bits

- Upspiral Router Bit (1/4)

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I start this circle jig project using a ¼ Lexan sheet. Lexan is like plexiglass but almost indestructible. First step is to cut a strip the same width as the original router base, in this case 4 inches.

I use an utility knife to scribe a mark on each side of my Lexan sheet then i scribe a line using a ruler.

I then use my bandsaw with a guide set at 4" from the blade to cut my Lexan Sheet. I really like the bandsaw because it's easy and fast to use, and it do the job really well. You could also use a table saw, jigsaw, circular saw to do this task, it depend on what tools you have in your workshop.

Now that the Lexan Strip is the same width as my original router base, I can unscrew that original router base from the router and stick it using some two way tape. It will be easier to drill the holes on the Lexan Strip at the exact locations for each holes without measuring anything.

Now we need to get some holes done in the Lexan Strip so we can fix it onto our router. And to do so, I need to find the exact center of each holes in the original router base. That's where the pilot point drill bit work at his best.

Pilot Point is like having a smaller drill bit at the end of your drill bit. So the widest part of the drill bit will sit tight in the holes of the original base plate, and the pilot point will find the exact center.

For this step, I just leave a mark with the drill bit for each holes I need to drill.

The screw need to sit flush in that Lexan Sheet, otherwise it will scratch our material when cutting circles.

Again, I use Pilot Point Drill bit for this task. I use a bigger drill bit so the upper stage of the bit is the same size as the screw head, and the pilot point is the same size as the thread of the screw. So it will make a perfect counterbore hole to sit the screw in it.

I install a 1/4 upspiral router bit in my router. This step is needed to make the next 14 small pivot point holes in the jig because we will measure each pivot point holes from the router bit hole.

I scribe a line in the middle of the lexan strip. Utility knife is really precise so I will know exactly where to drill my pivot point holes along the lexan strip. I then scribe a mark at every half inches starting at 2.5 inches away from the router bit.

The diameter of a circle is always two times the radius, so starting at 2.5" from the router bit will make a 5" circle. The last hole in my jig is 9" from the router bit, so I will be able to make circles from 5" up to 18".

I can add more holes to cut circles at custom sizes. Like I said, this is a BASIC circle cutting jig but it will serve my purpose for the project I need to make.

I drill the fourteen 1/8" holes along that line using my drill press.

I cut the corners on my Lexan strip using my bandsaw, it will give a cleaner look and also remove those sharp corners.

I need to enlarge the 1/4 router bit hole, otherwise sawdust and material won't get out easily when cutting circles. So to do so, I tried using a V groove router bit, but it didn't worked as expected! It melted the lexan sheet and made a bubble!

So I had to find a solution, and I tried to drill using a step bit and it worked great.

I recommend to enlarge that 1/4 using a holesaw. Because holesaw pilot drill bit is 1/4 so it the same size as the router bit. You can use a 1" holesaw or more so you get enough space around the router bit for the sawdust to get out.

We are done! Jig is complete and I'm ready to try it!

As you can see in the third picture, I'm using a dremel drill bit with a stone for my pivot point rod. It's easier to insert and to remove because the stone give you some grip, and it's not sharp like using a drill bit.

Now it's the fun part, and the simplest one!

I drill a 1/8 hole in my plywood.

I insert the dremel bit at the desired distance ( 6" in my case for a 12" circle )

I turn the router around using the jig, making multiple pass to ensure a smooth cut.

And voila! A perfect circle cutted in 2 minutes, with a basic jig that cost almost nothing to make!

I hope you guys have liked this project, feel free to ask any questions below!

Make sure you watch my video on youtube it really help me get more project out!

See you next time!