# Routing a circle



## Keith C (Jan 23, 2012)

I saw a youtube video on making a jig, Router 101 basics: make a circle cutting jig for discs, curves & Arcs, 'watch?v=b37LyYIO0sA' (on youtube), I think it is great, after drawing a circle with a compass and then trying to use my jigsaw and dremel and router to smooth it, and not doing a great job. Anyway, my question is about how to keep the center point on this type of jig from moving. Is it a special clamp that allows the jig to spin or do you just tighten enough to kind of hold the jig in place? I would think if you get enough friction to keep the center point, you won't be able to easily rotate. Thoughts?


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## Stick486 (Jan 4, 2013)

Keith C said:


> I saw a youtube video on making a jig, Router 101 basics: make a circle cutting jig for discs, curves & Arcs, 'watch?v=b37LyYIO0sA' (on youtube), I think it is great, after drawing a circle with a compass and then trying to use my jigsaw and dremel and router to smooth it, and not doing a great job. Anyway, my question is about how to keep the center point on this type of jig from moving. Is it a special clamp that allows the jig to spin or do you just tighten enough to kind of hold the jig in place? I would think if you get enough friction to keep the center point, you won't be able to easily rotate. Thoughts?


here's an improved link... 




FWIW that edge guide he is using is a circle cutting jig...

looks like his pivot is a thru bolt...

after all the jigs and what not I settled on these...
simple and easy to use...
Products |


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## Gaffboat (Mar 11, 2012)

+1 on the Jasper jig. It is easy to set up, easy to use, and takes up little storage space. Plus, it requires only a 1/8" pilot hole.


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## Stick486 (Jan 4, 2013)

Gaffboat said:


> +1 on the Jasper jig. It is easy to set up, easy to use, and takes up little storage space. *Plus, it requires only a 1/8" pilot hole.*


if you use a gorilla sized push pin you can go back and close the hole if you want...


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## Cherryville Chuck (Sep 28, 2010)

The simplest circle jig I've ever seen is the one Derek Willis came up with. You take a strip of panel board about 3/8" thick and drill a hole through it that is the same size as the O.D. of a router guide bushing. Then you drive a small nail through it the distance from the center of the guide bushing hole plus the radius of the bit you will be using. Set your plunge router with the bushing on it into the hole and rout away. Simple and free. http://www.routerforums.com/general-routing/31313-circle-trimming.html

If you are cutting a hole in a panel you want to hold the larger piece down solid and you also need to secure the center part that will be cut out down either with double sided tape or a center hole and through pin or some pin nails. Having that circle bounce around off the spinning bit can cause bad things to happen. By the way, it's best to be doing all this on a sacrificial work surface like an old sheet of ply.

I think one or more of Harry Sinclair's (Harrysin) tutorials may show him cutting out a circle.


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## CharleyL (Feb 28, 2009)

I like the Jasper jigs if the circle that I'm making is a dimensional increment that matches one of the incremental holes of the jig. If not, I have been using my CRB7 jig. Harry Sinclair has tutorials on making a jig similar to a CRB7 if you don't want to spend the money for a ready made CRB7, but the CRB7 with it's accessories has the ability to make larger circles than Harry's jig. 

There are a lot of ways to make circles with a router. The purchased jigs can make it easier if you will be making a lot of circles, but a home made version can be used if you don't see the need for spending money on one of the manufactured jigs or don't see the need for doing this very many times in the future. The very simplest jig can be made from a 4-6" wide piece of 1/4" plywood with the router attached to one end, with a large clearance hole for the router bit and a nail or screw driven through the plywood the correct distance from the router bit to match the radius of the circle that you want to make. You drive this nail or screw into the center of where you want to cut the circle, but don't drive it all the way in. It will provide the center pivot point. The router can then be used to cut an arc or circle in your project. If the material being cut is thick, make several passes at increasing depths of about 1/4" per pass until you cut through the material.

To keep the bit from cutting into the workbench I always place a piece of foam insulation under the work and set the router bit length long enough to cut through the work and slightly into the insulation board. My insulation board has been used many times and has grooves running in all directions, but none are more than about 1/4" deep, so I'm able to re-use it again and again for this purpose. A scrap sheet of plywood can be used if you don't have the foam material, or you can find a way to space your work above your bench with blocks of wood, etc. But you will need to keep these spaced away from the hole you will be cutting. I prefer the foam.

Charley


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## Stick486 (Jan 4, 2013)

Charley...

The Jaspers are incremented at 1/16''... adaptable to 1/32''....

often I see the suggestion to use foam board/insulation...
what do you do to control the nodules/bits/swarf/static cling of foam board that is produced...
who needs that stuff sucked into the router...
wouldn't several sticker type sticks placed under the piece getting cut be better...
stickers would be more economical...


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## RainMan 2.0 (May 6, 2014)

Keith seeing as your a rocket scientist , I wanted to share a picture of my late TransAm . I'm into photograph also , and photoshop . I was trying to think of a caption for his , and this was the winner lol


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## David Dickson (Oct 30, 2015)

You should check out these two episodes of the New Yankee Workshop. The Circle Cutting jig for the bandsaw starts around 14:50 in part 1. The one for the router starts around 10:00 in part 2.

Norm Shows You How to Build a Jig Part 1 of 2




 
Norm Shows You How to Build a Jig Part 2 of 2




 
In both cases, Norm uses a 1/4" bolt as the pivot, and drills a 1/4" hole where the centre point should go. He explains everything clearly, show how to build the jigs and how to use them.


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## DesertRatTom (Jul 3, 2012)

Lots of ways to do it, but all require putting some sort of center point to hold the jig in posiition. One possible way to do this without drilling the workpiece is to run a pin through a 1/4 chunk of ply, then affix another under the other end so it rides parallel to the pin piece or pivot. Double stick tape under the center pin board to hold it in place. I'd use a lot of tape, and be very gentle with the movement to avoid stressing the pin. I'd also mark the corners of the pivot piece in case it came loose on one of the passes. That way you could reposition it if it pulled loose.


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## jw2170 (Jan 24, 2008)

I still prefer Harry's circle cutting jig, and I have about 4 different types, including 3 different Jaspers...


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