Ok, just burned the servo.
I've reordered three so I can burn two more...
received the rest of my stuff for the gondola :-)
today is assembling day...
3d prints, bearings, linear-servo etc.
For precise mathematics one needs, of course, precise points.
That is why I have diverted the tooth belt.
Now the tip of the triangle is exactly on the center of the axis of the stepping motor.
Because of the bearing, the construction always rotates and the calculation point remains constant.
And because I want to have it stylish, I 3d printed it...
One Problem solved :-)