Router Circle Cutting Jig

[Brett Bobo]

What recommendations, suggestions, comments, etc. do you have on a homemade version of a router circle cutting jig. I realize they are straightforward to build but I'm curious as to what you find works best and provides the flexibility to cut any size circle. For instance, how do you lock the jig's cutting radius? Also, any photos of the finished product would be helpful.

Thanks,
Brett

[Joe Scharle]

Simplest jig is a piece of 1/2" MDF of suitable length and wide enough to support the router base. Drill a hole at one end large enough to hold a template bushing. Insert a small 4-6 penny finishing nail at the centerpoint and with the template bushing on your router you can cut a circle without changing the router's position in your hands. I also use a Milescraft on one of my routers.

[Tom Esh]

I made this one awhile back. Perhaps a bit overbuilt (1/2" aluminum stock for the pivot head) but sometimes a little metalwork is a fun diversion.
http://www.sawmillcreek.org/showthread.php?t=123696&page=3

[David Gregory]

Don't have any pics to show but I'll try to describe what I did a few years back. I took two threaded steel rods of correct diameter to fit in the openings of the router base except 4' in length. I then cut a 3/4 X 6" piece of Oak and drilled corresponding holes to accept the steel rods. I centered a #4 finish nail for a pivot in the Oak. The distance/span can be adjusted by jam nuts on the threaded rods giving the ability to cut up to an 8' dia. circle. Simple, inexpensive, and functional. Pretty darned accurate too amazingly.

[Chris Tsutsui]

Unless you need to make larger circles I would make a copy of the Jasper Circle Cutting Jig model 200. (Or buy it)

[Zach England]

Just buy the jasper jig.

[Jim O'Dell]

Mine's a piece of scrap 1/2" ply that is pretty flat. I took the base off my PC8529 and marked holes so that when I use the jig, I take the base off and use those screws to attach the jig. My pivot point is usually trial and error by measuring the outside edge of the bit I'm using, and mark a point on the jig and drill an 1/8" hole and use the shank of a 1/8" drill bit for my pivot point. It took several tries but I have a 6" mark and a 4" mark that makes a tight fit on S&D PVC pipe for making blast gates. Works great. Was real cheap too!! Jim.

[Brett Bobo]

Thanks for the ideas and to clarify, I'm primarily curious about how the cutting radius was engineered to give an infinite amount of settings, instead of just poking a hole and screwing the jig down. For example, I've seen a routed slot for almost the entire length of the jig with a threaded rod, washer, nut, and lock handle to set the radius to be cut and also provide a "dowel" in the threaded rod to seat into the workpiece. Just wondering if anyone has any better ideas to an infinite amount of settings and adjustability. Thanks

[Joe Chritz]

Sometime simple is better. This is likely one of those times. Just poke a hole and attach the router.

I don't think I have ever even kept a circle jig except in the scrap pile after it was done.

If you have a need for ability to adjust sizes, (lots of different size circles often) a Jasper jig is a pretty nice set up.

Joe

[Don Alexander]

i've used 1/4" ply for years for this application no need to spend money on it and no need to get more complicated than poking a hole thru it with a nail or screw for a pivot .... infinitely adjustable and very cheap to make a new one when it starts to get ragged also very easy to mark at set distances if you want to keep it for later use and easy to get zero clearance for chipout and dust control too

using a jig that a friend spent way too much money on years ago convinced me that simpler is better and alot cheaper too :)

[Myk Rian]

i've used 1/4" ply for years for this application no need to spend money on it and no need to get more complicated than poking a hole thru it with a nail or screw for a pivot .... infinitely adjustable and very cheap to make a new one when it starts to get ragged also very easy to mark at set distances if you want to keep it for later use and easy to get zero clearance for chipout and dust control too

using a jig that a friend spent way too much money on years ago convinced me that simpler is better and alot cheaper too :)
+1. I use 1/4" hardboard. Cheap is good.

[Jim O'Dell]

Thanks for the ideas and to clarify, I'm primarily curious about how the cutting radius was engineered to give an infinite amount of settings, instead of just poking a hole and screwing the jig down. For example, I've seen a routed slot for almost the entire length of the jig with a threaded rod, washer, nut, and lock handle to set the radius to be cut and also provide a "dowel" in the threaded rod to seat into the workpiece. Just wondering if anyone has any better ideas to an infinite amount of settings and "adjustability". Thanks

I guess you could route a long slot, and a recess on each side, build a piece that would slide in it, and be able to be locked down. I like my drill a new pivot point for each project/need. You could even use 2 pieces of t-track, one on each side of a home made router base and then build something between the 2 that would slide and have your pivot point of choice in it. The t-track could be as long as you think you might ever need. Jim.

[Harvey Melvin Richards]

I have 2 that I made. One is 1/2 BB plywood, and has an adjustable slot for length. It also has a couple of different length arms. I can route over an 8' radius with it.

The one I use the most however is 1/4" acrylic, about 2' long. It's a router sub base that tapers in it's length to about 2" wide. I put the bit where I want the radius cut, put the acrylic over the center point, and drill a 1/16" pivot hole. I use small blued box nails for pivots.