In case of interest, I am making slow progress - currently waiting for a cable to arrive to be able to test the motor - the idea is to be able to re-use a Bosch POF 500 router base/stand which has a 43mm router clamp, because this is the same as a Kress or similar router which can give low rpms. I am also hoping it will give options to make a much lighter weight sled in preparation for faster travel speeds in the future. Changing bits should also be very easy as the router comes in and out with just a hand knob to clamp it.
I tapped the top of one of the ‘slide posts’ for a bolt with which to mount a plate to hold the motor. The motor then turns the threaded rod via the coupler, which moves the threaded nut up and down the rod - pushing the router down in one direction, and allowing the springs to push it up in the other. The threaded rod is kept in place (to pull against) with a ‘c clip’ underneath the base.
Hopefully a video next week showing it in action, and being able to test how accurate the Z-travel is, whether there is too much friction or binding etc.
Matt