My DIY Harmonic Equatorial Mount

aka “How I Spent Way Too Much Time on a Really Cool Telescope Mount”

The Crazy Idea

Okay, so picture this: It’s 2 AM, I’m scrolling through astronomy forums (as one does), and I stumble upon this post about harmonic drives. Next thing I know, I’m sketching out plans for my own equatorial mount. My girlfriend thought I’d lost it. Maybe I had.

The “Why Not Just Buy One?” Phase

Look, I get it. There are perfectly good mounts out there you can just buy. But where’s the fun in that? Plus, have you seen the prices? I figured I could build something just as good (or at least, not totally terrible) for less.

Parts and Pieces: The Great Scavenger Hunt

Here’s where it got interesting. I became a regular at:

AliExpress: For the harmonic drives. Took forever to arrive, but hey, saved a bundle.
Amazon: Pretty much lived on their “Motors and Robotics” section. My recommended items got weird.
Xometry: These guys cut the metal parts. Pricy, but man, the precision was worth it.

Oh, and let’s not forget my 3D printer. I’m pretty sure it hates me now.

The Build: Blood, Sweat, and Gears

Remember when I said I could build this thing easily? Yeah, about that…

There were moments of triumph:

“It’s alive! IT’S ALIVE!” – Me, when the motors first moved without smoke.

And moments of despair:

“Why won’t you just ALIGN?!” – Also me, 3 hours into what should have been a 20-minute calibration.

The Specs

Two size 17 harmonic drives (sounds fancy, right?)
Some Nema motors with a 1:19 gear ratio
A bunch of aluminum I probably could have used to build a small spacecraft
More 3D printed parts than I care to admit

The Moment of Truth

After months of work, it was time to test this beast. I hooked up my trusty ASI 585 camera and my Samyang 135mm f/2 lens.

And you know what? It worked. Like, really worked.

60-second exposures? Nailed it.
120 seconds? Easy peasy.
300 seconds with guiding? Oh yeah.

I’m still working on pushing it to 600 seconds. The mount can probably handle it, but my patience during cloudy nights is wearing thin.

Was It Worth It?

YES, But the sense of accomplishment? The nights spent troubleshooting and tinkering? The look on my astronomy buddies’ faces when this thing tracked better than their fancy store-bought mounts? Priceless.

What’s Next?

Well, I’ve got some ideas for version 2.0

If you’re crazy enough to want to see more about this project (or need proof for my therapist that I actually built this thing), check out the video:

Watch the Madness Unfold