So in the process of developing custom automation for all of the components in the observatory, I’ve built the first of several focus motors using a 3-D printer I bought last October (and finally received in February!). The control uses an Arduino Nano to give me USB serial interface to it, with a cheap 5V stepper motor and driver (under $15 total off eBay). I designed and printed the gears and housing using my Robo 3-D printer. The whole assembly is designed to interface to the slow focus knob on my FeatherTouch focuser. I developed the firmware to have full variable speed control with variable acceleration and precision targeting. With the gearing ratios involved, I can position much more accurately than the scope will actually ever resolve to. Currently I only have a simple manual control program for the PC, but I’ll eventually finish writing the ASCOM driver for it as well. Enjoy!
Printing the base of the focus motor assembly on my new Robo 3-D printer.
Finished bottom of the housing that will hold the control PCBs for the focus motor. Not perfect, but good enough!
Printing the enclosure top and motor mount for the focus motor assembly.
Finished motor mount lid.
Various views of the combined top and base of the focus motor housing.
The internal grid was printed at a very low density, but the exterior layers didn’t do a good job of hiding it.
An Arduino Nano control board (blue) provides USB control of a stepper motor driver board (green) that then drives a 5V stepper motor. A power inlet allows running the motor off of a 12V supply for higher impulse current allowing the motor to run considerably faster with higher torque.
Installing the cover on the base. The parts are then heat welded together to create a solid assembly.
The focus motor mounts using two of the three screws on the Celestron focuser and uses two printed gears to drive the fine (10x) focus knob on a FeatherTouch focuser.
