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Custom telescope mount using harmonic drives and ESP32

svendewaerhert.com

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Re: Custom telescope mount using harmonic drives and ESP32

#71

Post by ejp »

alnwlsn wrote: post #46
waerhert wrote: post #18

Earlier quoted context omitted.

Though very grateful for projects like FreeCAD, I did encounter a fair bit of frustration while designing this. Especially random crashes, which only got worse as the project got more complex. As far as usage goes, it's mostly a matter of knowing how to do things in FreeCAD. I haven't encountered anything I could not achieve in FreeCAD. Having no experience in other CAD software probably helped sticking to it.

I came to FreeCad with some years background in Inventor, NX and SolidWorks. The jump from any of these to FreeCAD is not very big; you're doing a lot of the same things. But, most of the problems FreeCad has are solved in those, so you can sort of do anything in them and be none the wiser. In FreeCAD, you need to think a little bit more on how it's going to do things. But most people don't learn the big CADs first,…

OpenSCAD is great for functional parts, built of basic components. It can start to be good for moderate complexity components with the BOSL library (I use BOSL2) including chamfers/fillets where needed. And the parametric/customization aspect is second to none - IF it's built with that in mind.

Where it really falls down is when you need to somehow get data OUT of the model to feed to other shapes. I would love to be able to specify a chamfer or fillet along a contact edge of two other shapes, but unless you know the exact contact shape, location, and size a priori you will have a tough time getting anything to line up. If you want to use a mesh or model as a negative, every model's zero coordinate needs to be just right or it will just be entirely misaligned.

I've also tried to spend some time performance optimizing for render/output. It is not cooperative at all. It will just soak CPU time for a minute at a time for not even a complex shape! As pseudosudoer said, it really goes off the rails.

But for functional connectors, adapters, and replicating parts, it's great to be able to leverage my software skills in 3D modeling!

Re: Custom telescope mount using harmonic drives and ESP32

#73

Post by gattr »

zokier wrote: 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.

Another interesting project might be capturing host star light curves for transiting exoplanets. For a number of closer ones, it can be done conveniently from a backyard with just a photographic lens. Here's one amateur using ASI178MM-c with a Canon FD 300 mm:

https://astropolis.pl/topic/60163-wasp-10-b-w-pegazie-1270-m...

Re: Custom telescope mount using harmonic drives and ESP32

#74

Post by double0jimb0 »

fusslo wrote: post #5

I've been using freeCAD for about 3 years now. Looking at what he was able to make with it blows my mind. I love freeCAD, but I don't think I've ever been so continuously frustrated by a piece of software

I've found ChatGPT and Claude to be extremely helpful as guides for this sort of stuff. As long as the software has decent/good documentation for the features you are trying to create, the AI does a great job telling you how to do things. There's definitely deep end stuff that the AI doest have enough reference material for, but I find it much quicker than blinding clicking through stuff or speeding watching YouTube videos.

You can also ask it to build a study guide for you to help build foundational knowledge.

But as always, expect some hallucinations, so ask it to provide links/references.

Re: Custom telescope mount using harmonic drives and ESP32

#75

Post by waerhert »

double0jimb0 wrote: post #74
fusslo wrote: post #5

I've been using freeCAD for about 3 years now. Looking at what he was able to make with it blows my mind. I love freeCAD, but I don't think I've ever been so continuously frustrated by a piece of software

I've found ChatGPT and Claude to be extremely helpful as guides for this sort of stuff. As long as the software has decent/good documentation for the features you are trying to create, the AI does a great job telling you how to do things. There's definitely deep end stuff that the AI doest have enough reference material for, but I find it much quicker than blinding clicking through stuff or speeding watching YouTube…

Yes! And when you need advice on an electronic circuit you can export it in netlist format from KiCAD. This is a textbased representation of the schematic which is very understandable by LLMs

Re: Custom telescope mount using harmonic drives and ESP32

#76

Post by mkipper »

stavros wrote: post #40
waerhert wrote: post #30

Earlier quoted context omitted.

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).

If you're pulling the datasheet from the vendor website, you can also skim the list of documentation and see if there are any application notes available for the part.

For more "complicated" parts (e.g. lots of signals, high frequency, high power, etc.), integrating the part into a board design isn't necessarily straightforward. Rather than putting a ton of detail in the datasheet, the vendor will sometimes have an entirely separate document with design guidelines for the part.

Re: Custom telescope mount using harmonic drives and ESP32

#77

Post by Aaargh20318 »

donkeybeer wrote: post #51
waerhert wrote: post #45

Earlier quoted context omitted.

Not sure what you mean with complex mechanism. The mount has a similar architecture to other commercially available mounts like the HEM15 iPolar for example.

Oh ok. I didn't know harmonic drives were standard in commercial mounts.

They have become popular in the last few years. They are smaller, lighter and thus more portable than traditional mounts. They also don’t need to be balanced with a counter-weight (although they usually allow for a counter weight to increase payload capacity, they don’t need to be perfectly balanced). This all saves in set-up time.

One disadvantage compared to traditional mounts is that they absolutely need guidance, and with a pretty fast guide loop at that (like 0.5s). You can’t do long unguided exposures with a strain wave. But anyone who’s serious about astrophotography is guiding anyway so that’s not really a big deal.

Re: Custom telescope mount using harmonic drives and ESP32

#78

Post by teamonkey »

zokier wrote: 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.

First principles it is not, but people use the Seestar S50 roboscope with a distraction grating to get readings on the emission spectra of stars.

Re: Custom telescope mount using harmonic drives and ESP32

#79

Post by teamonkey »

artgship wrote: post #13

I love this so much. Is there any open-source software that calculates where a given planet or star might be (based on your coordinates) and automatically finds the star / planet and then follows it? Can these mounts be used with such software if it exists?

Yes, the OnStep firmware used here has drivers for ASCOM and Indi, which are communications protocols commonly used by most astronomy software on Windows and Linux. It also speaks the older Meade LX200 serial protocol, which is another common method.

For example, Stellarium on your phone can connect to the mount’s wifi station and control it.

Re: Custom telescope mount using harmonic drives and ESP32

#80

Post by alnwlsn »

ejp wrote: post #71
alnwlsn wrote: post #46

Earlier quoted context omitted.

I came to FreeCad with some years background in Inventor, NX and SolidWorks. The jump from any of these to FreeCAD is not very big; you're doing a lot of the same things. But, most of the problems FreeCad has are solved in those, so you can sort of do anything in them and be none the wiser. In FreeCAD, you need to think a little bit more on how it's going to do things. But most people don't learn the big CADs first,…

OpenSCAD is great for functional parts, built of basic components. It can start to be good for moderate complexity components with the BOSL library (I use BOSL2) including chamfers/fillets where needed. And the parametric/customization aspect is second to none - IF it's built with that in mind. Where it really falls down is when you need to somehow get data OUT of the model to feed to other shapes. I would love to be…

>I would love to be able to specify a chamfer or fillet along a contact edge of two other shapes

Yes, this is how the big cad programs work, they are 'constraint based'. You pick points and lines from other features (or other parts) and add whatever new geometry you want, and a solver fills in the rest. Features build off each other in this way. In OpenSCAD, you are the solver. But, the big programs have a ton of buttons, and scripting, while there, is usually hidden.

It's kind of like the difference between and Photoshop. Photoshop has a ton of useful tools inside, but if all you want to do is crop the bottom 30px from 2000 images, it's better to have a script do that. The scripts can technically do everything that Photoshop can do, but for other things it's easier just to click a few buttons and be done than reinvent the wheel from the ground up each time.

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