Thanks James for the interest.
No bevel on the sliding arm, just a right angle cut with a matching dado on the under side of the jig base. I routed a "T" slot in the top of the sliding arm and inserted a "T" Bolt that is used as a means to hold tight the dimension from the bit to the pivot pin. If you look at the third pic above, you'll see the threaded end of the "T" bolt protruding through the jig base. For the time being, I put a standard 1/4-20 nut with washers to secure the "T" bolt, but I will retro-fit it with a five star knob after my next visit to Rockler. I used the circle jig today to cut a circular plexi-glass router table base plate and corresponding circular dado. The jig performed quite nicely and made short work of the match up work. I'll post pics of the finished router table top once I complete that task.