Evostar ED50 Motor focuser mount

[gazza]

Hello,

the Evostar ED50 guider makes a nice cheap widefield imager when combined with the Starizona matching field flattener. The only issue is that there are no commercial motor focusers available to fit it. A friend who is an engineer (Maurice Valimberti) designed the focuser mount here for me.
It was printed with Esun PLA+ on an Ender 3 Pro using 20% infill.
I used 3 brass inserts that are melted into the PLA using a soldering iron. These were sized for m3 x 12mm cap screws.
The motor is mounted with the cap screws that come with the Focus Motor. There are slots in the mount so you can shift the motor to tighten the drive belt.
The GT2 timing belt was made by cutting the belt a bit too long trimming 3 teeth off leaving the bare belt and overlap gluing the two ends of the belt with CA
The ZWO motor has backlash, as does the helical focuser. In NINA I used backlash 700, step size 1500. This is because the focuser has an extremely fine action.
The large gear is an extremely tight fit, but size can be adjusted using the "horizontal expansion" setting in Cura if it is too small/large for your focuser.
There are holes include for locking screws on the gear and motor mount, but I made mine a tight fit and don't need them.

Pics attached

If you want a copy of the stl's pm me - do not want to put them up publicly just yet, but happy to send you a copy.
cheers
Gary