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Custom telescope mount using harmonic drives and ESP32

svendewaerhert.com

31–40 of 118 posts

Re: Custom telescope mount using harmonic drives and ESP32

#31
post #24

This is great! I never understood how people learn how to make solid PCBs, I've made a few things but I think I must be missing some decoupling capacitors or resistors or whatever, because my microcontrollers aren't very stable. How do you all just know what stuff to put on the PCB? Do you read the datasheet for the component and add whatever is there?

Yeah, you have to read the data sheets. Beyond that, use decoupling caps for all power pins, as close to the chip as you can, and make one side of the PCB a ground plane. These 2 things should solve most of your issues.

Re: Custom telescope mount using harmonic drives and ESP32

#32

After using standard EQ-mounts for so long, seeing something without a counter weight just looks wrong to my neanderthal brain. My current mount weighs 40lbs, the counter weight is 17lbs, and the tripod legs are 20lbs. So that's over 75lbs of weight and size of gear to move around every time it goes on a road trip. This design looks like it was a fraction of that. Color me intrigued

I estimate a load capacity of 8-10kg. It's not designed for the really big equipment cause I also would like to take it on camping trips. If I were to do this again I will definitely add a threaded hole to mount a counterweight bar. I've noticed the tracking accuracy drop slightly when the mount is in the most overhanging positions.

Re: Custom telescope mount using harmonic drives and ESP32

#34

Earlier quoted context omitted.

Those who have bought into "free" closed source software simply haven't been burned hot enough by it yet. It might take a while, but you'll learn your lesson one of these days.

Honestly it’s useful enough that I’d pay the several hundred dollars per year if I had to. It’s that much better. The money spent would be well worth it (for me) for all the time saved over using FreeCAD. I’ve used multiple professional CAD packages and I’m just not interested in going back. People sneer and tell me I’m going to get burned some day, but meanwhile I’ve been using it to great effect for many years for…

I'm not going to agree to any of the "free" (you sign away all rights to the things you made free) tiers. Not that anyone would ever use my things but it's out of principle. FreeCAD has issues but is good enough for most people. And once you want to do really complicated things and also can cope the hundred of euros per years fine, but don't complain other people should do the same because you can.

Re: Custom telescope mount using harmonic drives and ESP32

#35

After using standard EQ-mounts for so long, seeing something without a counter weight just looks wrong to my neanderthal brain. My current mount weighs 40lbs, the counter weight is 17lbs, and the tripod legs are 20lbs. So that's over 75lbs of weight and size of gear to move around every time it goes on a road trip. This design looks like it was a fraction of that. Color me intrigued

Just for comparison:

I've got a Juwei-17 (Onstep harmonic drive with performance similar to the ZWO AM5N, but at nearly half the price) paired with the ZWO TC4 carbon fibre tripod.

The tripod has a load capacity of 50 kg (110 lbs) and weighs just 2.5 kg (5.5 lbs). The harmonic drive mount has a load capacity of 13 kg (29 lbs), or 18 kg (lbs) with a counterweight, and weighs 5.5 kg (12 lbs). Alltogether, the setup weighs about 8 kg (18 lbs) since I don't have to use counterweights.

Re: Custom telescope mount using harmonic drives and ESP32

#36

Earlier quoted context omitted.

Those who have bought into "free" closed source software simply haven't been burned hot enough by it yet. It might take a while, but you'll learn your lesson one of these days.

Honestly it’s useful enough that I’d pay the several hundred dollars per year if I had to. It’s that much better. The money spent would be well worth it (for me) for all the time saved over using FreeCAD. I’ve used multiple professional CAD packages and I’m just not interested in going back. People sneer and tell me I’m going to get burned some day, but meanwhile I’ve been using it to great effect for many years for…

Unfortunately, those who (used to) use Autodesk Eagle can't say the same, and they were willing to pay.

Re: Custom telescope mount using harmonic drives and ESP32

#37

After using standard EQ-mounts for so long, seeing something without a counter weight just looks wrong to my neanderthal brain. My current mount weighs 40lbs, the counter weight is 17lbs, and the tripod legs are 20lbs. So that's over 75lbs of weight and size of gear to move around every time it goes on a road trip. This design looks like it was a fraction of that. Color me intrigued

I estimate a load capacity of 8-10kg. It's not designed for the really big equipment cause I also would like to take it on camping trips. If I were to do this again I will definitely add a threaded hole to mount a counterweight bar. I've noticed the tracking accuracy drop slightly when the mount is in the most overhanging positions.

It looks like you have a typical OTA attached, what camera are you using with that? I've only ever used my DLSR attached to the OTA for prime photography, but it is heavy. I've learned to test the position by hand of the camera through the full rotation to see how the orientation of the camera will change throughout the night to prevent hanging situations and so it has forward tension. I noticed more backlash type issues when it had reverse tension. The one thing I haven't done yet, is to just attached the camera to a small ball head to do tracked wide angle images. However, I really haven't done any dark sky shooting in many years, pre-Starlink. I wonder if long tracked exposures with wide angles would ever not be affected by Starlink trails

Re: Custom telescope mount using harmonic drives and ESP32

#38

So is the accuracy and stability he achieved better or worse than the commercial mount?

Short answer: it's in the same ballpark as other mounts of the same size. The theoretical accuracy for RA is 0.198″ (65,536 steps and 100:1 reduction) and for DEC is 0.253″ (256*200 steps, 100:1). In practice many things will reduce this accuracy: seeing, proper polar alignment, sturdiness of the wedge and tripod all account for some loss in accuracy. My highest achieved accuracy was probably around 1″ during brief moments, I'm sure with excellent seeing this could reach <1″ performance.

Re: Custom telescope mount using harmonic drives and ESP32

#39
post #14

One thing that I'd be interested in is having telescope mount suitable for doing quantitative measurements, basically doing astrometry from first principles. To me solving the orbits of planets (etc) based solely on my own measurements sounds very compelling. It would be like retracing the steps Kepler etc did.

Kepler did it without a telescope, using Tycho's naked-eye observations.

Re: Custom telescope mount using harmonic drives and ESP32

#40
post #24

This is great! I never understood how people learn how to make solid PCBs, I've made a few things but I think I must be missing some decoupling capacitors or resistors or whatever, because my microcontrollers aren't very stable. How do you all just know what stuff to put on the PCB? Do you read the datasheet for the component and add whatever is there?

Checking the datasheet is essential, they usually show the “must-have” parts around a chip. Beyond that, good habits are adding decoupling caps close to the pins, keeping ground solid, and following the reference layout. I also learned a lot just by listening to experienced designers explain their choices, like here: https://www.youtube.com/watch?v=aVUqaB0IMh4

Thanks, I'll read more datasheets, as I've kind of just been winging it (with terrible results, as you saw).
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