Just use a router with a 1/2 inch straight bit set it up on a 6 inch
wide board with the bit centered at 3 Inch from the edge and side of the
board. Then measure back 24 inch from the inside of the bit and 14inch from
the out side of the bit drill two holes on these marks then use the same
drill bit and drill a hole in the center of a 48 by 48 sheet of ply or MDF
cut your outer circle first and then your inter circle do not cut all the
way through the material leave about 1/8 th of an inch then cut out with a
jig saw and trim down with a flush trim bit.
Always use the radius of a circle to cut one with this method.A good
rule of thumb is always convert any measurement under 12 feet to inches only
and you will avoid a lot of mistakes.

Chris

"Mark and Kim Smith" wrote in message
...
As part of a project I'm making, I need to make a 4' ring. The outer
circumference, which will be the 4' diameter, will be cut on my band saw
by setting up a jig that has a pivot 2' from the blade. I'm looking for
suggestions for the best way to cut the inner diameter which will be at
2' - 4" giving the "ring" a 10" width. The material is 3/4" thick. So
far I'm thinking my jig saw or my router with a fence set at 10" and
multiple passes. Any other suggestions? As always, thanks in advance!!