I continue with my attempt to build a 3D-printed 3" focuser. I have now made the CADs for the rack & pinion gears, started with the worm gear, make the focus shaft holder and the focus chassi. Lot of details left to solve.
Here is my document, see page 7 to 9:
http://www.astrofriend.eu/astronomy/...-friction.html
Maybe it will not work with enough precision, but it's exiting to do at least a prototype. I can always hand over the CADs to someone who has a metal 3D-printer.
/Lars