Built by JZ.
For my build log, checkout this page on my website.
The following YouTube video documents all the processes with no explaination:
The same video can also be found on bilibili.
AlkaidMount is a DIY aluminum HarmonicDrive German style equatorial mount with a ~25lbs unbalanced or >70lbs balanced load capacity, with a self weight of only ~16lbs. Each axis consists of a 100:1 HarmonicDrive gearbox, followed by a 27:1 planetary gearbox, driven by a Nema17 stepper motor.
Weight capacity is calculated with gearbox load limits as well as rigid body simulation. Note that I have not yet done any torture tests, so those numbers are all theoratical. I've only tested it on the two scopes I own - an unbalanced Williams Optics GT71 setup (~15lbs) and balanced a Meade LX200 8" SCT setup (~25lbs not including the counterweights). Both setups worked beautifully.
This repo contains ALL the design files (CAD, manufacture drawings, PCB files, software) to make the AlkaidMount. I made this repo public to inspire other ideas. Due to the difficulty in sourcing the exact same model of the two HarmonicDrive's (unless you buy new:), replicating the exact same mount would be hard. However modifying this design to suite other HD models shouldn't be too hard.
| 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 :{ | - | - |
| Name | Quantity | Drawings | Datasheet |
|---|---|---|---|
| Teensy 4.0 | 1 | - | - |
| ESP-32 (for wifi control) | 1 | - | - |
For parts on the PCB, see PCB/parts.txt.
Most parts were made with 2D waterjetting, with not too much post-processing (tab removal, tapping if needed). Some parts have holes on the side, so some milling was involved.