Replies

1. 
   RW | Oct 06, 2005 05:18am | #1

   use 1/4 ply and make an elongated baseplate for the router. Use the routers base screws to attach. Draw a line down the center. Plunge the bit through. Measure from the edge of the bit at the line your distance, drill a pilot hole just big enough to slide around a tack. Insert tack. Rout. Instant circle.

   You can do more or less the same on a router table. You need some fixture that mounts in an expanding track (like featherboards). Use the track and a sheet of something thin like 1/4 ply to mount it to, drive a pin from the underside, and lock the track in place, setting the pin the distance from the bit edge of the radius you want. Of course, you need to mount the track far enough away from the board being routed to be able to turn the handwheel that expands the track, so it only works on smaller pieces, but thats almost ideal. Big pieces you can freehand. Smaller stock I think life is easier to be able to use the fence to put a hold down on it and use the table.

   "If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man." - Mark Twain

2. 
   Mongo | Oct 06, 2005 07:13am | #2

   http://www.woodworkingtips.com/etips/etip030201wb.html

   A picture's worth a thousand replies...this was the first hit on google.

   With your small radius the pin may actually be under the router baseplate.

3. 
   TomT226 | Oct 06, 2005 02:20pm | #3

   Get a PC template guide set.  Use the guide that has a 3/4" ID.  I forget what the OD is.  Lay out a circle of 7" plus what the difference of the bit and OD of the guide is on a piece scrap ply.  Jigsaw the circle and clean up the edges.  Tack over the work, and rout the circle keeping the router tight aginst the edge.