Thanks, Harry, I'd been exploring that method but my jig design (as yet unbuilt) was way over complicated. I've attached a pic of the preliminary Sketchup work. I was thinking in terms of a dedicated base plate 'cause I didn't want to start down a path of Swiss cheesing the stock plate (I've got a Bosch 1617). I added curved pivot tracks for locking down the jig once the width was set.
I will add that using shims on one side of the work piece will offset the center of the mortise/dowel hole toward the shim by a distance of half the width of the shim. Some help on my faulty math on that was offered by John (jschaben).
Also calibration to insure the mortise is centered on the work piece is a simple mater. Just place a piece of of round stock (drill bit or drill blank) into the router chuck and then with the router base loose secure the jig on it and, to either side, some scraps of a width equal to the diameter of the round stock and tighten the base down.
Nice to know I was on to something of real use. I'll probably complete it now.
Last edited by GulfcoastGuy; 12-07-2012 at 08:55 AM.