SV80ST DIY Focuser

Here are files and photos of my DIY focuser for my Stellarvue SV80ST telescope. The controller is based on [anat's Leonardo-based controller](https://www.cloudynights.com/topic/594658-pnp-focus-the-simplest-ever-arduino-focus-controller/).

I used the NEMA 17HS13-0404S-PG27 motor anat referenced in his post and opted to use a belt drive. With this combination, a single motor step equates to a drawtube movement of ~3 microns. At f6, the critical focus zone (CFZ) for green is ~83 microns, giv