[chuckknigh]

If wear is a concern, instead of tapping the PVC, use a little epoxy and off the shelf steel nuts on each end -- should provide a tougher surface, and as strong as the epoxies are today, that won't be the weak point of the assembly. The PVC is there only to act as the adjustment device...and one that *anyone* can build. My thought is that it could be tapped more accurately, and provide a smaller surface area.

(Or would an alternate metal be better for the threads? Brass and aluminum, for example, are used extensively in the helical focussing mechanisms of cameras, because of their extremely low friction when used together. Steel and brass are used in clockmaking for similar reasons, and the brass gears don't show undue wear, despite the sliding friction present between them and the steel gear teeth.)

Now...how about the Z-axis ideas? I'm working on some final designs, and would really appreciate some feedback on the Z axis design ideas. The cantilevering of the router support just "rubs me the wrong way."

-- Chuck Knight