Each axle is held in a drilled channel sandwiched between two pieces of Baltic Birch ply, tightened securely with screws.  This same method is used to secure the axles of the neck support platform.  I used three bearing per axle to make things as stable as possible and to average out any irregularities in the bearings, as small as those tolerance issues might be.  I also swapped out the larger Black and Decker router for a Makita laminate trimmer that would be able to get closer to the heel and carve more of the neck.  On one side of the sled there are two separate pieces of plywood that secure the axles, so that the router can be installed as close as possible to the edge.

 

Considerable improvements were also made to the platform that supports the neck.  In my earlier conversation with Dan, I had mentioned that the platform was a single piece of plywood that was too flexible and that I intended to improve things by adding another layer.  Dan then suggested something that should have been obvious to me, but sadly wasn't (did I mention two heads are better than one?): Dan suggested orienting the reinforcing ply at 90 degrees to the top layer, thereby virtually eliminating the tendency to flex.  This I did (three pieces of plywood below the upper piece) and I also added two pieces of angle aluminum - this platform won't bend!

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The images show how the removable cams, held tight by a set-screw, are inserted in a box at each end of the platform.  These images also show another improvement to the first jig: the block of UHMW that houses the bearing (also secured with a set-screw) which hold the axles.

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It was Dan of course who originally suggested having the cam run on bearings, and I decided to route a cavity in the hardwood blocks and drill a hole to accommodate a short axle.  Unlike the blocks in the original jig, these blocks are fixed in position (since a good height has been established) and do not move up and down in slots (the photo at left suggests that slots were in fact still used, but ultimately these were replaced with holes).  The blocks are still removable, tightened with large plastic knobs, since the platform needs to be removed to change cams when necessary.

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In use, I was holding and turning the platform with my left hand, as the right worked the router sled.  I wasn't particularly happy with my hand being that close to a spinning router bit and the fact that if the bit caught the sled could be "thrown" a little.  So I made two further improvements.  I added removable enclosures (shown in this article's first image) that limit upward travel, and stop blocks that limit travel along the jig in both directions.  I haven't seen enclosures like this on any of the videos I studied, all those jigs with routers free to rise up, but they seem to work well and I'm glad I added them.  And safety aside, the stop blocks are necessary to avoid inadvertently running the bit into the neck heel or headstock.