Hadley Harmonic: Strain Wave Equatorial Mount

Overview
 

Hadley Harmonic is designed to be a low cost alternative to COTS strain wave equatorial mounts. I recommend running OnStep* on an esp32. It integrates nicely with hillexed's Hill Mount and is designed to hold the imperial version of the hadley telescope.

Printing

I highly recommend PETG or PA6 for most of the parts. PLA may work but is likely not durable enough for supporting a heavy telescope.

For the large parts, tolerances aren't too important, and they can be printed at 0.2mm layer height.

I would recommend printing the entire gearbox at 0.12mm layer height and IMPORTANTLY with the arachne wall generator to get good tooth definition.

Assembly

Hopefully this onshape document https://cad.onshape.com/documents/0d7fc740e7c5314c540c3628/w/6e99ef7bf3d2f7eff98a592a/e/aae395cc1f02b471f0e1d0e5?renderMode=0&uiState=6a712d1f5d9455abadc2cccd along with the provided BOM will suffice for assembly, but feel free to reach out with questions!

Bill of Materials

In addition, you will need various M3 and M6 bolts*, a 12V power source (I use a 3s 2200mAh lipo battery) and a micro usb cable for programming.

Firmware

The ESP32 runs the OnStepX firmware which can be connected to a smartphone to calibrate and control. The firmware requires a config file which is included here

https://github.com/TigeyJewellAlibhai/Hadley-Harmonic-Firmware

Future Improvements

This project is in a prototype stage and still needs work. While the files and parts should get you started, you may need various adjustments and refinements for a fully functional design. I plan to add the following soon:

• Homing switches for both axes

• Adjusted gear ratio to be a whole number

• Improved tolerances and backlash

• Adapters for Hadley Metric and others

• Battery mount

* More info on these coming soon!!