Amazing project and write up, very good timing too! I’ve been into amateur astronomy since I was 13, owning a few telescopes and spending many hours with family at star parties.
This week I pulled out our big Meade 10” SCT and our small Meade 4” Newtonian to show my 7yo son the moon and Saturn from my parents Bortle 8 backyard. It was wonderful seeing his awe and surprise, and the fact that my parents were there to see it too.
That 10” SCT is on an old fork mount which is motorized but has no GOTO capabilities at all. I’ve also gone down the rabbit hole of researching mount options, thinking I could just buy my way out of it. However, as much as I like the idea of GOTO, a big part of the fun is finding the objects. So I’ve never been able to pull the trigger. I did buy a ZWO 585MC though, I’ve always wanted a dedicated cooled camera.
That said, we have lost way too many hours to trying to find objects. The Telrad isn’t always enough!
I’ve been looking into using my 3D printer and electronics know-how to build my way out of this. I was even thinking of swapping the motors for NEMA 17 steppers.
Then I stumbled upon PiFinder, and I think this project is going to be the exact balance of automation and Push-to guidance that I would like.
It’s a wonderful hobby and I think the latest in 3D printing and PCB manufacturing does mean we’re going to be able to solve a lot of these problems soon.
>However, as much as I like the idea of GOTO, a big part of the fun is finding the objects.
I love reading this because it shows how different people are and how much room there is in the hobby for different interests. I am grateful for goto mounts specifically because finding the object is one of my least favorite parts of it. :D
Thanks! If you hook your ZWO up to Kstars/EKOS you can use plate-solving in software to find out exactly where your scope is pointed at and then adjust accordingly.
One tiny nit on this amazing project / write up. He mentions that the traces have to be extra wide to support 24V. In truth though, the higher voltage means lower current, which means if anything the traces can be less wide. The size of the traces is determined by the current they carry, the voltage determines how much space must be between the traces (but it’s unlikely to be an issue at these voltages).
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
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, they learn Fusion. The few times I've tried Fusion, it's given me a headache. It's probably a bigger headache going the other direction.
Then, there are those who do all their CAD work in OpenSCAD. They scare me.
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!
OpenSCAD is genuinely great for the right kind of user. If you’re familiar with CSS and have experience with animations in the past, you already possess the skills to be productive with OpenSCAD. In my opinion, the most challenging aspect is getting accustomed to the disconnect between visualizing something and manipulating it, as it’s done through code.
I really liked OpenSCAD as a concept, but when I started designing things that had a fair bit of complexity the rendering engine really shit the bed. This was a powerful rig as well.
Haha, the thought of using OpenSCAD briefly crossed my mind when I found out about it but I didn't want this project to take a year extra to complete. I do consider exploring some of the other CAD alternatives though if budget permits.
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.
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
For real, I've been using FreeCAD for small hobby stuff for 7 years and still often find extremely frustrating UX issues in features new to me, stuff that wouldn't pass QA (I'm a FE dev and know a thing or two about that). When I proceeded to understand why overconstraints are an error and not a warning, I immediately discovered a multiple page thread on FreeCAD forums with regulars gaslighting how everything was exactly as needed because "performance", despite this being a deliberate choice, not a solver limitation. This gatekeeping attitude is really off-putting, the project needs a UX expert and a good community manager to root out that power user crap.
Can concur. I jump between OnShape and FreeCAD in my free time. OnShape feels very polished. I go back to FreeCAD, because I've bought some models, I don't want to publish in OnShape's free tier.
It's amazing how much can be done, but anything that I think will take an hour, lasts 6. Many times into the night.
I think it’s great that we have FreeCAD as an option and I’m excited to see it mature.
That said, I recommend Autodesk Fusion free tier for anyone who just wants to get quality work done quickly. Some will refuse to use it on principle and that’s fine for them, but it really is quality software free for hobbyist use with trivial restrictions.
EDIT: Getting downvoted, presumably for suggesting a non-OSS software to get a job done. However I’d recommend anyone who just wants to get work done at least consider the options at their disposal. Not every software decision needs to be made on principle.
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.
I think I could be burned by Fusion, recreate everything in OnShape, get burned by OnShape, then redo everything on a 3rd software and still be better off.
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 hobby projects that I can share around and edit easily.
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.
> (you sign away all rights to the things you made free) tiers.
Do you have a source for this? Or are you speculating?
> but it's out of principle
Great that it works for you. I have limited time for hobbies and I can’t justify making choices based on principle to avoid hypotheticals that even you admit aren’t going to happen.
> but don't complain other people should do the same because you can.
I’m not complaining. Anyone who wants to use a certain software based on principle is free to do so.
I’m sharing recommendations from my own experience and that of my peers. If the goal is to focus on the project you’re trying to do instead of fighting with software then people should be aware of their options.
The irony (or at least difference) here is that KiCAD is way better than Eagle ever was (or whatever the Fusion name is now). FreeCAD isn’t better than onShape, F360, or SolidWorks (and not even close, IMO).
SolidWorks hobbyist subscription is what I would point people to. It's the cheapest of the "real" CAD packages that will give portable skills to other packages.
Three years should be more than enough time to have learned how to perform a few simple extrusions and pockets. What we're looking at here is essentially a pipe with a cap.
Free cad gets really complicated the moment you want to do surface modeling.
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:
Sounds like a really interesting potential project. I've been pondering a system that would make amateur observations usable beyond pretty pictures. Single frames captured could be shared in raw form along with metadata (time, coords, calibration frames), potentially allowing aggregators to process it for scientific research (or even prettier pictures). The Vera C. Rubin Observatory is now able to capture the entire southern hemisphere in a couple of days. Imagine having our capturing software contributing to a planet-wide crowdsourced telescope array.
Brahe did have large quadrants (and armillarys) though, which in this context is not all that different especially when you factor in how much light pollution impacts observations.
Not to take away from Brahes exceptional ability at naked eye observations, but the key here is having some sort of instrument that enables precise measurements, be it telescope on a mount or huge mural quadrant.
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
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.
basically every part will provide a minimal schematic in the datasheet or have a reference design you can copy from
some stuff may be somewhat glossed over, like usage of ground planes or which traces you're supposed to keep short, but when those are important they'll usually be mentioned, or even spelled out in a application note
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.
This is really impressive! I considered buying a big harmonic drive mount for my scope, but the cost is really prohibitive.
I have experienced the pain of getting ekos/kstars/indi tools to work well on my personal scope. If you want to try driving indi devices via python I have some python code (it's not super polished, but it does enough for my needs): https://github.com/dahlend/contindi
Cool project. What prompted you to write this? Asking because EKOS already has pretty good scheduling features (I've seen, not used). Along the way I did vibe-code a TUI for controlling the INDI server running on the MeLE 4C minicomputer attached to the telescope: https://www.svendewaerhert.com/content/blog/telescope-mount/... - I switched to a headless setup using a remote indi server after having a bad experience with reliability using remote desktop in Gnome. I'll probably put this TUI on Github once I clean it up a bit.
I joined my local Maker's Space specifically for the machine shop. They had a CNC machine that I took the classes on to be certified. I designed my first simple plate design piece for cinema camera support gear in the CAD software they had connected to the machine. There was even a bit of software that generates the G-code with a simulator to check for head crashes. However, every time I went up there to actually try to build the piece the unit was down because someone crashed the head and destroyed bits. Instead, I wound up using the regular metal working machines to hand make the first piece. It ended with square corners instead of rounded, and some of the hole alignment wasn't as precise as intended. I wish I would have known of one of these types of sites to have the piece still CNC'd instead.
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?
Stellarium and Kstars (which has EKOS built in) are both very good planetarium software. Both can interface with indiserver, which can talk to many astronomy devices such as mounts, filter wheels, cameras. I use Kstars mainly for controlling the mount, and Stellarium mainly for finding nice targets.
> Is there any open-source software that calculates where a given planet or star might be (based on your coordinates)
Sure. Skyfield is a python library to calculate that (among others). Right on the front page is an example how to calculate the azimuth and elevation of Mars: https://rhodesmill.org/skyfield/
Loved the write up, well done to the author. I get the same feeling building stuff with freecad and then printing it. Feels like there is no limit to what can be done. After going through the growing pains of designing stuff that was just poor and difficult to print I’m now confident enough to send it to be printed by jlcpcb or pcbway. And when they tell me to accept the risk of a failed print then I think, “I feel your pain, good luck”. So far I have never gotten a failed print back. Maybe a little warped but way better than my attempts. If I never have to use my large resin printer ever again I will be happy.
On the pcb front, I dread going through those final steps in the pcb ordering process. No matter how many parts I preorder, there is always something that is unavailable. So much churn in component availability.
Thanks, glad you enjoyed this. It's good to be in a place where you're confident things will turn out alright when you send your designs halfway across the world to be manufactured. I've so far only had positive experiences with JLCPCB, especially with issues that turn up during their review process. I forgot to add a fillet around the edge where the DEC axis sticks out of the tube and they sent me a quick message to say "We can't guarantee a 100% right angle here cause of the minimum radius of our bits". I assumed they would just gloss over this and manufacture it anyway, but they gave me a chance to review it just in case it was important to the design (it wasn't in this case, but still). On the PCB side, I used a plugin for KiCAD that automatically generates the production files and the bom.csv - It's really critical to review this when you load it into their tool because the automatic recognition/matching with components sometimes has mistakes in it.
I built a small two axis direct-drive mount (https://mjbots.com/ controllers are great) to track satellites and aircraft with an RF antenna. One of the things that stood out in the article for me was the yolo send to JLCPCB. It spoke volumes about your confidence in the CAD design, maybe one of these days I'll get there hahaha.
Great design and writeup btw, it looks as good if not better than most of the commercial designs out there. You might enjoy Bruce Van Deventer's vids on youtube: https://www.youtube.com/@djcheckonetwo/videos (direct drive mount with 26 bit renishaw ring encoder might whet your appetite a bit)
Thanks for the compliment and links! Can you tell me more about the aircraft tracking? I've been toying with the idea of being able to select a nearby airplane on flightradar24 and instructing the mount to follow it as it comes into view. Not sure how I would even begin building that.
You could actually build a self-contained unit with a raspberry pi and a rtlsdr based receiver. They do a great job picking up ADSB directly from aircraft 100+ miles away.
You'd just need to write some glue code to take the ADSB streams from a given plane (could pick based on area or strongest signal or whatever) and convert that to alt/az from your reference frame to feed the motor controllers for tracking. Your mount would clearly be adequate for optical tracking so you'd want to add some smoothing and likely some kind of tracking corrections/trim but you'd be close right off the bat.
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.
So do you think that complex mechanism ended up no better than the normal mounts? It could be execution too, I am no good at experiments and sometimes even "proven" designs end up a bit subpar, so it could be the design was alright.
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.
You could sell kits for this btw. There would be demand. And I think you could be quite successful.
The reason is that Trump is tariffing the hell out of the main Chinese telescope accessories manufacturer, ZWO. So if you can provide a non-Chinese alternative....
Think of trying to be Prusa 3D solution in the astrophotography area.
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
I switch between the cheap Byomic 76/700 newton and my Sigma 600mm lens (Canon EF but using an adapter to fit the Olympus body). I tried to get the DSLR looking into the newtonian but it was just too heavy, causing the plastic focuser to simply bend way off axis. I've since bought a dedicated astro camera (Neptune C II) which fits alright on the newtonian. I'm keeping the Byomic 76 only for visual observations now. Looking to buy a proper refractor of around 480mm. The Sigma 600 does alright with the DSLR but isn't very sharp, hard to focus and suffering from some coma. It's good enough to learn the ropes for now.
Yeah, in astro, the quality of the lens shows in much more disappointing ways that regular photography. Any softness from the lens can be part of the art in regular photography, but in astro is a lesser image.
Maybe I missed it, but where in Europe are you? Are the temps part of your softness issue? I'm in Texas, and during the summer when it's prime time for central part of the Milky Way the seeing is horrible from the extreme high temps and the disturbance it causes in the air.
I've been looking at getting a dedicated astro camera as well to reduce that weight as well as free up the camera body to go back to its primary mission of time lapse. I've already gone down the rabbit hole deep enough to have a secondary scope and camera to use as a guide scope to overcome any of the slight mis-alignments during polar alignment. The hole is deep and easy to fall into. Be careful when looking down that hole wondering how far you'd be willing to go as you'll be deeper than you expected before you realize you've left the edge.
Yeah I didn't expect such a stark difference in image quality from the same lens when using it for day photography vs astrophotography. Just goes to show how incredible a proper astrograph is. I'm located in Belgium: high light pollution and very humid skies. The only targets worth bothering here are close to zenith. It's a fun rabbit hole to be in :)
At my home, it is so light polluted, I don't even bother with attempts at zenith objects. I joke about every hotel in town is a 5-star hotel because you can literally only see 5 stars at night. With a 4 hour drive, I can be in one of the darkest spots in the state. To get to the darkest, it would be at least 8 hours. Either way though, it's Texas, so the high temps play havoc on image quality.
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.
Amazing project and write up, very good timing too! I’ve been into amateur astronomy since I was 13, owning a few telescopes and spending many hours with family at star parties.
This week I pulled out our big Meade 10” SCT and our small Meade 4” Newtonian to show my 7yo son the moon and Saturn from my parents Bortle 8 backyard. It was wonderful seeing his awe and surprise, and the fact that my parents were there to see it too.
That 10” SCT is on an old fork mount which is motorized but has no GOTO capabilities at all. I’ve also gone down the rabbit hole of researching mount options, thinking I could just buy my way out of it. However, as much as I like the idea of GOTO, a big part of the fun is finding the objects. So I’ve never been able to pull the trigger. I did buy a ZWO 585MC though, I’ve always wanted a dedicated cooled camera.
That said, we have lost way too many hours to trying to find objects. The Telrad isn’t always enough!
I’ve been looking into using my 3D printer and electronics know-how to build my way out of this. I was even thinking of swapping the motors for NEMA 17 steppers.
Then I stumbled upon PiFinder, and I think this project is going to be the exact balance of automation and Push-to guidance that I would like.
https://www.pifinder.io/
It’s a wonderful hobby and I think the latest in 3D printing and PCB manufacturing does mean we’re going to be able to solve a lot of these problems soon.
>However, as much as I like the idea of GOTO, a big part of the fun is finding the objects.
I love reading this because it shows how different people are and how much room there is in the hobby for different interests. I am grateful for goto mounts specifically because finding the object is one of my least favorite parts of it. :D
Thanks! If you hook your ZWO up to Kstars/EKOS you can use plate-solving in software to find out exactly where your scope is pointed at and then adjust accordingly.
One tiny nit on this amazing project / write up. He mentions that the traces have to be extra wide to support 24V. In truth though, the higher voltage means lower current, which means if anything the traces can be less wide. The size of the traces is determined by the current they carry, the voltage determines how much space must be between the traces (but it’s unlikely to be an issue at these voltages).
Good catch and explanation!
Nice. Harmonic drives are my 'favourite' machine element. The lash is silly and watching the carrier(?) deform is hypnotic.
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
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, they learn Fusion. The few times I've tried Fusion, it's given me a headache. It's probably a bigger headache going the other direction.
Then, there are those who do all their CAD work in OpenSCAD. They scare me.
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!
OpenSCAD is genuinely great for the right kind of user. If you’re familiar with CSS and have experience with animations in the past, you already possess the skills to be productive with OpenSCAD. In my opinion, the most challenging aspect is getting accustomed to the disconnect between visualizing something and manipulating it, as it’s done through code.
I really liked OpenSCAD as a concept, but when I started designing things that had a fair bit of complexity the rendering engine really shit the bed. This was a powerful rig as well.
Haha, the thought of using OpenSCAD briefly crossed my mind when I found out about it but I didn't want this project to take a year extra to complete. I do consider exploring some of the other CAD alternatives though if budget permits.
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.
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
For real, I've been using FreeCAD for small hobby stuff for 7 years and still often find extremely frustrating UX issues in features new to me, stuff that wouldn't pass QA (I'm a FE dev and know a thing or two about that). When I proceeded to understand why overconstraints are an error and not a warning, I immediately discovered a multiple page thread on FreeCAD forums with regulars gaslighting how everything was exactly as needed because "performance", despite this being a deliberate choice, not a solver limitation. This gatekeeping attitude is really off-putting, the project needs a UX expert and a good community manager to root out that power user crap.
That was the classic GIMP problem too.
Meta comment: damn it's good to see something worthwhile at #1 on HN this morning.
Can concur. I jump between OnShape and FreeCAD in my free time. OnShape feels very polished. I go back to FreeCAD, because I've bought some models, I don't want to publish in OnShape's free tier.
It's amazing how much can be done, but anything that I think will take an hour, lasts 6. Many times into the night.
I think it’s great that we have FreeCAD as an option and I’m excited to see it mature.
That said, I recommend Autodesk Fusion free tier for anyone who just wants to get quality work done quickly. Some will refuse to use it on principle and that’s fine for them, but it really is quality software free for hobbyist use with trivial restrictions.
EDIT: Getting downvoted, presumably for suggesting a non-OSS software to get a job done. However I’d recommend anyone who just wants to get work done at least consider the options at their disposal. Not every software decision needs to be made on principle.
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.
I think I could be burned by Fusion, recreate everything in OnShape, get burned by OnShape, then redo everything on a 3rd software and still be better off.
FreeCAD is just that far behind.
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 hobby projects that I can share around and edit easily.
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.
> (you sign away all rights to the things you made free) tiers.
Do you have a source for this? Or are you speculating?
> but it's out of principle
Great that it works for you. I have limited time for hobbies and I can’t justify making choices based on principle to avoid hypotheticals that even you admit aren’t going to happen.
> but don't complain other people should do the same because you can.
I’m not complaining. Anyone who wants to use a certain software based on principle is free to do so.
I’m sharing recommendations from my own experience and that of my peers. If the goal is to focus on the project you’re trying to do instead of fighting with software then people should be aware of their options.
Unfortunately, those who (used to) use Autodesk Eagle can't say the same, and they were willing to pay.
The irony (or at least difference) here is that KiCAD is way better than Eagle ever was (or whatever the Fusion name is now). FreeCAD isn’t better than onShape, F360, or SolidWorks (and not even close, IMO).
SolidWorks hobbyist subscription is what I would point people to. It's the cheapest of the "real" CAD packages that will give portable skills to other packages.
Three years should be more than enough time to have learned how to perform a few simple extrusions and pockets. What we're looking at here is essentially a pipe with a cap.
Free cad gets really complicated the moment you want to do surface modeling.
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...
Sounds like a really interesting potential project. I've been pondering a system that would make amateur observations usable beyond pretty pictures. Single frames captured could be shared in raw form along with metadata (time, coords, calibration frames), potentially allowing aggregators to process it for scientific research (or even prettier pictures). The Vera C. Rubin Observatory is now able to capture the entire southern hemisphere in a couple of days. Imagine having our capturing software contributing to a planet-wide crowdsourced telescope array.
Kepler did it without a telescope, using Tycho's naked-eye observations.
Brahe did have large quadrants (and armillarys) though, which in this context is not all that different especially when you factor in how much light pollution impacts observations.
Not to take away from Brahes exceptional ability at naked eye observations, but the key here is having some sort of instrument that enables precise measurements, be it telescope on a mount or huge mural quadrant.
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).
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.
basically every part will provide a minimal schematic in the datasheet or have a reference design you can copy from
some stuff may be somewhat glossed over, like usage of ground planes or which traces you're supposed to keep short, but when those are important they'll usually be mentioned, or even spelled out in a application note
For an MCU: find a development board with schematics available, and use that as a reference/starting point.
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.
Excellent, thank you. I already do the plane, but not the caps. Thanks!
This is really impressive! I considered buying a big harmonic drive mount for my scope, but the cost is really prohibitive.
I have experienced the pain of getting ekos/kstars/indi tools to work well on my personal scope. If you want to try driving indi devices via python I have some python code (it's not super polished, but it does enough for my needs): https://github.com/dahlend/contindi
Cool project. What prompted you to write this? Asking because EKOS already has pretty good scheduling features (I've seen, not used). Along the way I did vibe-code a TUI for controlling the INDI server running on the MeLE 4C minicomputer attached to the telescope: https://www.svendewaerhert.com/content/blog/telescope-mount/... - I switched to a headless setup using a remote indi server after having a bad experience with reliability using remote desktop in Gnome. I'll probably put this TUI on Github once I clean it up a bit.
I'm most impressed with being able to order the CNC'ed metal parts. I'm just a novice cad designer and I'd love to learn that capability.
I joined my local Maker's Space specifically for the machine shop. They had a CNC machine that I took the classes on to be certified. I designed my first simple plate design piece for cinema camera support gear in the CAD software they had connected to the machine. There was even a bit of software that generates the G-code with a simulator to check for head crashes. However, every time I went up there to actually try to build the piece the unit was down because someone crashed the head and destroyed bits. Instead, I wound up using the regular metal working machines to hand make the first piece. It ended with square corners instead of rounded, and some of the hole alignment wasn't as precise as intended. I wish I would have known of one of these types of sites to have the piece still CNC'd instead.
It's super easy actually ! 1) Upload step file, 2) see what's possible:
https://jlccnc.com/cnc-machining-quote
Xometry and pcbway are alternatives, among many others
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?
Stellarium and Kstars (which has EKOS built in) are both very good planetarium software. Both can interface with indiserver, which can talk to many astronomy devices such as mounts, filter wheels, cameras. I use Kstars mainly for controlling the mount, and Stellarium mainly for finding nice targets.
Thank you!
> Is there any open-source software that calculates where a given planet or star might be (based on your coordinates)
Sure. Skyfield is a python library to calculate that (among others). Right on the front page is an example how to calculate the azimuth and elevation of Mars: https://rhodesmill.org/skyfield/
Thank you!
Cool project. Strain wave mounts are fantastic. Just ordered a wave 150i myself. Can’t wait to not having to waste time balancing my scope anymore.
Loved the write up, well done to the author. I get the same feeling building stuff with freecad and then printing it. Feels like there is no limit to what can be done. After going through the growing pains of designing stuff that was just poor and difficult to print I’m now confident enough to send it to be printed by jlcpcb or pcbway. And when they tell me to accept the risk of a failed print then I think, “I feel your pain, good luck”. So far I have never gotten a failed print back. Maybe a little warped but way better than my attempts. If I never have to use my large resin printer ever again I will be happy.
On the pcb front, I dread going through those final steps in the pcb ordering process. No matter how many parts I preorder, there is always something that is unavailable. So much churn in component availability.
Thanks, glad you enjoyed this. It's good to be in a place where you're confident things will turn out alright when you send your designs halfway across the world to be manufactured. I've so far only had positive experiences with JLCPCB, especially with issues that turn up during their review process. I forgot to add a fillet around the edge where the DEC axis sticks out of the tube and they sent me a quick message to say "We can't guarantee a 100% right angle here cause of the minimum radius of our bits". I assumed they would just gloss over this and manufacture it anyway, but they gave me a chance to review it just in case it was important to the design (it wasn't in this case, but still). On the PCB side, I used a plugin for KiCAD that automatically generates the production files and the bom.csv - It's really critical to review this when you load it into their tool because the automatic recognition/matching with components sometimes has mistakes in it.
I built a small two axis direct-drive mount (https://mjbots.com/ controllers are great) to track satellites and aircraft with an RF antenna. One of the things that stood out in the article for me was the yolo send to JLCPCB. It spoke volumes about your confidence in the CAD design, maybe one of these days I'll get there hahaha.
Great design and writeup btw, it looks as good if not better than most of the commercial designs out there. You might enjoy Bruce Van Deventer's vids on youtube: https://www.youtube.com/@djcheckonetwo/videos (direct drive mount with 26 bit renishaw ring encoder might whet your appetite a bit)
Thanks for the compliment and links! Can you tell me more about the aircraft tracking? I've been toying with the idea of being able to select a nearby airplane on flightradar24 and instructing the mount to follow it as it comes into view. Not sure how I would even begin building that.
You could actually build a self-contained unit with a raspberry pi and a rtlsdr based receiver. They do a great job picking up ADSB directly from aircraft 100+ miles away.
You'd just need to write some glue code to take the ADSB streams from a given plane (could pick based on area or strongest signal or whatever) and convert that to alt/az from your reference frame to feed the motor controllers for tracking. Your mount would clearly be adequate for optical tracking so you'd want to add some smoothing and likely some kind of tracking corrections/trim but you'd be close right off the bat.
I’ll look up that plugin, thanks!
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.
So do you think that complex mechanism ended up no better than the normal mounts? It could be execution too, I am no good at experiments and sometimes even "proven" designs end up a bit subpar, so it could be the design was alright.
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.
I am a bit idly curious since I plan to build a telescope sometime. Nothing as complex as this, just a manually guided dobson.
You could sell kits for this btw. There would be demand. And I think you could be quite successful.
The reason is that Trump is tariffing the hell out of the main Chinese telescope accessories manufacturer, ZWO. So if you can provide a non-Chinese alternative....
Think of trying to be Prusa 3D solution in the astrophotography area.
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
I switch between the cheap Byomic 76/700 newton and my Sigma 600mm lens (Canon EF but using an adapter to fit the Olympus body). I tried to get the DSLR looking into the newtonian but it was just too heavy, causing the plastic focuser to simply bend way off axis. I've since bought a dedicated astro camera (Neptune C II) which fits alright on the newtonian. I'm keeping the Byomic 76 only for visual observations now. Looking to buy a proper refractor of around 480mm. The Sigma 600 does alright with the DSLR but isn't very sharp, hard to focus and suffering from some coma. It's good enough to learn the ropes for now.
Yeah, in astro, the quality of the lens shows in much more disappointing ways that regular photography. Any softness from the lens can be part of the art in regular photography, but in astro is a lesser image.
Maybe I missed it, but where in Europe are you? Are the temps part of your softness issue? I'm in Texas, and during the summer when it's prime time for central part of the Milky Way the seeing is horrible from the extreme high temps and the disturbance it causes in the air.
I've been looking at getting a dedicated astro camera as well to reduce that weight as well as free up the camera body to go back to its primary mission of time lapse. I've already gone down the rabbit hole deep enough to have a secondary scope and camera to use as a guide scope to overcome any of the slight mis-alignments during polar alignment. The hole is deep and easy to fall into. Be careful when looking down that hole wondering how far you'd be willing to go as you'll be deeper than you expected before you realize you've left the edge.
Yeah I didn't expect such a stark difference in image quality from the same lens when using it for day photography vs astrophotography. Just goes to show how incredible a proper astrograph is. I'm located in Belgium: high light pollution and very humid skies. The only targets worth bothering here are close to zenith. It's a fun rabbit hole to be in :)
At my home, it is so light polluted, I don't even bother with attempts at zenith objects. I joke about every hotel in town is a 5-star hotel because you can literally only see 5 stars at night. With a 4 hour drive, I can be in one of the darkest spots in the state. To get to the darkest, it would be at least 8 hours. Either way though, it's Texas, so the high temps play havoc on image quality.
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.
This post reminds me of the beauty of open source. Well done build and a great project summary!