Alan Zhao, a PhD student with the Perceptual Science Group at MIT CSAIL, created this Harmonic Drive equatorial mount. He graciously shared his design under GNU GENERAL PUBLIC LICENSE.
This is a rather complex project that requires access to a metal shop and some knowledge of electronics. However, we are posting this project with the hope that it will inspire some to build mounts like this.
If you can manufacture mounts like this and need help to comercialize them at a reasonable price, feel free to reach out to us using our contact form.
Photos
Video
Video log Crafted By JZ documenting the build
Hardware
The Parts You'll Need
BOM - Hardware
| Name | Quantity | Drawings | Datasheet |
|---|---|---|---|
| Harmonic Drive CSF-17-100-2UH-LW | 2 | Drawings | Datasheet |
| Nema 17 with 27:1 Planetary Gearbox | 2 | Drawings | Datasheet |
| 1/8" Aluminum plate | 12"x12" minimum | - | - |
| 1/4" Aluminum plate | - | - | - |
| M4x8 | many :) | - | - |
| M3x8 | not that many :] | - | - |
| M5x8 | a few :{ | - | - |
BOM - Electronics
| Name | Quantity | Drawings | Datasheet |
|---|---|---|---|
| Teensy 4.0 | 1 | - | - |
| ESP-32 (for wifi control) | 1 | - | - |
For parts on the PCB, see PCB/parts.txt.
Manufacturing Guide
Most parts were made with 2D water-jetting, with not too much post-processing (tab removal, tapping if needed).
Some parts have holes on the side, so some milling was involved.
More documentation is available on the GitHub repository of this project.
CAD Model
The CAD model is publicaly available at OnShape.com.
Accesss to Onshape Standard is available free for non-commercial projects where all user data is stored in a public work space.
Software
OnStep Telescope Controller
OnStep is a computerized telescope goto controller, based on Teensy or Arduino control of stepper motors.
It supports Equatorial Mounts (GEM, Fork, etc.) as well as Alt-Az mounts (including Dobsonians, and the like.)
OnStep was designed, from the beginning, as a more or less general purpose system and provisions were made in the firmware to allow for use on a variety of mounts.
Website of the author od OnStep: Stellarjourney.com