A simple idea, Chris.

The only downside that comes to mind is that the centre hole for the workpiece has to be large enough to accommodate the size of the lock nuts. Do you also intend to drill the 1/4 hole all the way through the work piece?

 

after using the lock nuts to secure the threaded rod in the track, they would come off.

for a thicker piece where i don't want to have the 1/4" center hole all the way through, i could use a short threaded rod that did not go all the way through.

 

Perhaps an easier way would be to use a piece of shelf support instead of T track. Mount the router on the end of the board then set the circle size by putting a finishing nail through one of the slots in the shelf support and then into the wood you are going to cut. The slots in the shelf supports are about 1/2" apart so unless you had to be exactly accurate it would be a quick set up. If you had to be dead on it would take a little more precision setting the nail.

 

Chris, I know it is way more than you probably want to spend, but here is the easy way..

Miter Track & T-Track - T-Track Sliding Fixture Block Kit

Of course it should not be that hard to make a substitute!

 

duane, heh, yeah, that is more than i'd want to spend ... you know me!

but that is very much like what i am planning, thanks for sharing it