Celestron NexStar SLT90 focuser

thingiverse

A motorized focuser for a Celestron NexStar SLT90, with a SCAD file that may allow adjustments for other telescopes. It houses a 28BYJ-48 stepper motor. The motor mount contains a long curved bar which can fit securely in the gap between the scope tube and the dovetail bar. A cog slides over the focus knob, allowing it to be removed with ease. I used a Raspberry Pi (running Astroberry) to control this, though the same mount could be used for an arduino or any other microcontroller. A cheap IR remote allows control locally and over the network. Blog post as part of an Astroberry build series is available at: https://samndave.org.uk/ourdoc/2021/12/15/astrophotography-with-a-raspberry-pi-part-3-focus-control/ with supporting code on GitHub at: https://github.com/DaveHartburn/astroberryAddons In the SCAD file, there are a number of variables, such as showMounting, showMotorCog etc. Set these to 0 or 1 to control what to display. Warning: A motorized focuser such as this does not detect when your focus has been turned to the limits, using a motor to drive beyond the limits will likely damage your telescope. A close focus should be achieved by eye and a focuser used for fine adjustments.