Motorizing dobson mount

Here is my attempt at making a DIY Go-To dobson mount, using two old stepper motors taken from printer. At microstepping and low rotation speed they have more than enough torque to move the wooden mount including telescope. Motor control is done using two Allegro drivers and Arm7 microprocessor. Prior using Go-To capability, software needs position of two reference stars. It is also necessary to provide a flat levelled surface for the mount.

Finished mount, with all the circuitry and wires visible.

The hardest part of the build is making a worm drive or something similar to it. After some testing I decided to make a grooves in worm wheel using two-part epoxy repair putty. As a worm and its shaft I used nylon threaded rod.

Grooves in worm wheel.

The final product was in use only few times, enough that I determined its pointing accuracy and smoothness of movement. Accuracy of pointing to a desired object was within 0.5°, enough that the object was visible in 25mm ocular with ~1° of FOV. Smoothness of movement when looking through ocular, while the scope was moving, event at microstepping was not very good. The jerky motion between motor steps was visible. For this reason I never tried to upgrade software for object tracking.

More photos in gallery.

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