I had initially thought of mounting the guide pin to the table insert by using two (the only two) threaded holes, one for the starter pin and the other to mount a clear plastic shield over the starter pin. I took accurate measurements of the hole positions, relative to the router centerline, to get the pin assembly in the ballpark, to be fine tuned by holding an alignment shaft in the router collet. I abandoned this approach for my first attempt where I tried using the clear plastic chip shield, detailed above.
Returning to the idea of mounting the pin guide to the table insert, I machined a 5/16" thick alum. plate with holes for the table mount and for the pin holding assembly. This time, instead of machining something from scratch, and wanting a faux-collet system, I opted to use the compression fittings for 1/8" copper tubing. I drilled and tapped the alum. plate for the 1/8-27 NPT threads on one of the compression fitting. I held the tap square with a spring loaded tapping guide to ensure the threads would be perpendicular to the surface of the plate. I also used that guide while screwing the fitting into the plate, again to try to keep it square.
Here is a photo of the completed guide pin, with the 1/8" guide pin in place, but showing the compression fittings used in the assembly. I have to be careful when tightening the nut so as to not crimp the compression wedge onto the pin shaft. Snugging it lightly with a wrench so far has proved sufficient to hold the pin secure without crimping the wedge. If I were going to use this system much, I would slice the wedge so that it could not crimp.
This shows using a 1/4" shaft in the router collet to align the jig to the router centerline.
Here is the completed compression fitting pin guide in use. The bottoms of the tooth gullets on my existing gears are not as deep as the CNC routed gears. So, here I am using the CNC gear as a pattern to deepen the teeth gullets.
This is Option 2 from above, modifying my existing gears. BTW, I had previously tested the CNC gears and they mesh cleanly and rotate freely. After modifying one each of the three sizes of my existing gears, they also mesh cleanly and rotate freely. This setup works very well and I can see using this for the rest of my existing gears.
But... that is not the end of the story. Just before embarking on the second iteration with the compression fittings, I did some looking online for router pin guides. I found a lot of pin router machines where the router was above the table and the pin in the surface of the table. Not what I was looking for. I found two above table mounted pin guides for the traditional router table:
One, a fairly simple and much less expensive, the Daisy Pin Router: https://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/daisypin.html
and the second, the Veritas Pin Router Arm: Veritas® Pin Router Arm - Lee Valley Tools
This latter one is far beefier and larger than I expected, when I ordered it. It arrived today and whoa! is it huge. It is intended to mount on the corner of a Veritas router table and it almost does on my Bosch table, but not quite. I'm still working on the best approach but it is looking like building an extension for the rear of my table is the best. I will be building and extension anyway for the Incra LS Positioner System that will be arriving next week.