Hi Harry
You should give the Jasper Jig a try out
it will amaze you how easy it is to cut out a circle from 2" to a 18" with just a brass guide in the router base, you just drop it in and plunge the router in and it's that quick no rods to fool with,no screws,no ruler just one small 1/8" pin hole to drill in the center of the circle.
Plus you can do 256 holes sizes with one small jig.
I have made many circle jigs and use many Fac.ones and the Jasper jig is the best one I have used.
Just a NOTE **** you can get one for 29.oo US dollars at Amazon.com no need to pay list price for it, the best money you will spend for tools this year
If you want to see all the circle jig I have made and paid for just ask and I will post a snapshot or two of them.
Bj