When we were kids, it was a rite of passage to read the newly arrived Edmund catalog and dream of building our own telescope. One of our friends lived near a University, and they even had a summer program that would help you measure your mirrors and ensure you had a successful build. But most of us never ground mirrors from glass blanks and did all the other arcane steps required to make a working telescope. However, [La3emedimension] wants to tempt us again with a 3D-printable telescope kit.
Before you fire up the 3D printer, be aware that PLA is not recommended, and, of course, you are going to need some extra parts. There is supposed to be a README with a bill of parts, but we didn’t see it. However, there is a support page in French and a Discord server, so we have no doubt it can be found.
It is possible to steal the optics from another telescope or, of course, buy new. You probably don’t want to grind your own mirrors, although good on you if you do! You can even buy the entire kit if you don’t want to print it and gather all the parts yourself.
The scope is made to be ultra-portable, and it looks like it would be a great travel scope. Let us know if you build one or a derivative.
This telescope looks much different than other builds we’ve seen. If you want to do it all old school, we’ve seen a great guide.
…So not PLA, what’s the suggested material? ABS? PETG? Some stupid exotic filament?
Looked through a couple linked pages, one translated from French, and no real mention of what WAS used to print this.
What’s the issue with PLA? I assume heat warping. That should only be an issue in certain specific areas.
In the support page there’s a README:
PETG – ASA – ABS (NO PLA) 2000 gr
it says ABS ASA PETG in the readme
i’d like to know why they recommend against PLA. my personal feeling is that PLA’s no good for durable goods, because it becomes so brittle. and this does seem to require a thin part holding the secondary up, which will actually certainly fail in a small number of years. but i imagine they have different concerns.
Almost certainly moisture and form creepage under load, it’s just not great for functional parts that need to keep their shape to any great degree like this would need.
Yeah I figured this was most of it. Any amount of creep in the sockets for the struts holding the mirrors would immediately ruin collimation and all sorts of other things.
PLA is not all that rigid, and rigidity is everything in a telescope. Orientation with respect to gravity would significantly distort the truss in noticeable ways. The recommended filaments form much more rigid structures once they cool.
But PLA is stiffer than any of the other plastics mentioned.
Why not print PLA parts, add a wax sprue, slather on plaster, then burn out the PLA. Last step, use this as a mold to cast an aluminum part from scrap soda cans
But PLA sags under the weight with time, unlike other mentioned filaments. You will have to readjust everything after a week, after a month telescope will go to trash, I have unfortunate experience with PLA and telescopes…
Ummm, PLA is more rigid than some of the recommended filaments. So it’s not that. PLA isn’t as tough as the others mentioned and isn’t as durable so that may be part of the issue.
PLA is very stiff, it just creeps. That’s the real problem.
I’ve been 3D printing stuff for about 12 years. In that time I have printed no more than 2 kg of PLA filament. Once I realized that PLA prints won’t hold their shape if you leave them in a hot car for a few minutes, I stopped using PLA.
Any time you consider printing something with PLA, ask yourself two questions:
1) do I want the print to be around for a long time?
2) can I absolutely guarantee the print will never be left inside a car or truck parked in the sun?
If either answer is “yes”, don’t use PLA.
In other words, don’t use PLA, ever.
Oops, senior moment. If the answer to the second question is “No”…
Not only heat, it does warp and sag under even the smallest weight after some time.
Fully agree with you. PLA is overrated; PETG gets a bad rap for being goofy, but in my experience modern PETG is just as easy to print. It also has the advantage of being really easy to sand
Darn autocorrect.
s/goofy/goopy/
i don’t know if the PETG filament has improved but i think what’s improved is the extruder. when i was trying to decide what to switch to after abandoning PLA, i found a bunch of forum posts of people…i don’t know, 2-3 years ago complaining about PETG and then the follow up saying “oh i upgraded to the new extruder and i haven’t had that problem since.” so i figured i’d try my luck, and, lo, my new cheapo extruder cuts the mustard
the only thing i don’t like about PETG is that it’s finnicky about bed adhesion. i raised bed temp all the way to75C i think, and i wash the bed with dish soap every couple months and it’s alright but i rarely had any of that sort of problem with PLA (otoh i was always playing with ‘blue painters tape’)
If you want to sand PLA, wet-sand it. Like, under running water. Works really well.
The issue is that sandpaper microscopically heats the PLA high spots, and turns it to a nicely lubricating liquid, preventing any more material removal. Keeping it cold with a stream of water keeps it solid.
heh i printed PLA over a decade and never once left it in a car. but thanks for answering my question why people want PLA HT :)
Don’t use PLA ever? Um, no. That’s very poor advice. It’s cheap, ubiquitous, versatile, and ideal for many applications. It’s not perfect for some projects, so yes, use another material in those cases.
Question 0 is: Is this art, a toy, or a prototype?
If the answer is no, you can stop, because you shouldn’t be printing it anyway.
You could anneal it, then it’s deformation temp is higher than most other common thermoplastics.
I also had the hot car moment. I stopped printing stuff that would matter in heat with PLA, but plenty of things stayed PLA if they were not dimensionally important, or would live 100% of the time in air conditioning. It’s all about the application.
A telescope will be in a hot car, it will get hot from focused light (even moonlight will heat up a telescope by a surprising degree!) and it will go through all other sorts of stresses… So I agree on the no PLA, but I was frustrated by the statement of a negative without any positive suggestion :)
The first line of the description is “README ON MY PAGE” with a link to his page, and the readme is linked at the top of said page…
the focuser is interesting. if i was inclined in this direction i might print the focuser and maybe even a couple brackets but i would definitely be drawn to more traditional assembly techniques for the rest of it. but it seems like there’s a lot of people out there who don’t mind running 2kg of filament through their printer for a single project.
fwiw this seems to use a 150mm f/5 mirror, which is what i have in my favorite scope. i think it’s a great size, big enough but not too big. compatible with wide views but still easy to get a lot of magnification. orion used to sell a good dob in this size as the “starblast 6” for about $300, which doesn’t seem like much more than you’d pay to put together this kit (mirror alone seems to be $130). i’m not going to put much effort into the search but last time i looked around i was surprised to see no one seems to be making a telescope like that at the moment…kind of a bummer given that chinese manufacturers have made the price come down for a lot of quality optics, but this size seems to be abandoned. one of the rare cases where a bit of kit actually became less common / affordable?? maybe i just looked wrong.
I still have my edmund 6″ reflector I bought when I was 16 (1978)
Yes, and the Edmund catalog was the coolest, then Heathkit.
Heathkit! I forgot about that catalog. I loved looking through it back in the day. But I never could convince my dad to buy the heathkit robot kit they had in the back. I really wanted to try building it, soldering iron in hand!
I built the Hadley after seeing it mentioned here on Hackaday:
https://hackaday.com/2022/11/04/3d-printed-newtonian-telescope-has-stunning-looks-hadley-breaks-the-bank/
I used PLA. Why not for this one?
cool that you actually built it!! have you gotten much use out of it? is it fun? (i’m saying that as someone who hasn’t pulled my scope out since last year)
unless the spider vanes holding the secondary are a lot thicker than they look then i would be really worried about that part in particular becoming brittle over time. i’d be paranoid about it breaking off and falling onto the primary. but you’re probably gentle with your scope..
what are you using for a focuser? the 3d printed helical (screw thread) focuser seems really frustrating to me (i’ve used a factory-made one of those before), but depending on the eyepieces you use maybe it isn’t so bad? seems like probably the thing i’d experiment the most with if i built one
I also made the Hadley after seeing it here, it was my first telescope and has been absolutely brilliant.
It’s been to outreach sessions multiple times and so far the only damage was when I left it in my car and the altitude bearings melted! This was unexpected being in the UK but it taught me a lot about PLA. Surprisingly the spider vanes which are only 2 wall thicknesses (the alternative curved spider) has never had any issues but I can understand why PLA isn’t recommended for something you might leave in a car or travel with.
For Hadley I swapped to the Hypatia crayford focuser and don’t think I’ll ever change it, so easy to use but does require a few specific parts to buy and make aside from 3d printing. The stock one I found difficult to get to the right tolerance but there have been a couple of revisions now so might be better. I might have a go at printing the focuser from this telescope too as it looks really neat.
I got a Bambu A1 mini last year which was a huge speed and experience upgrade over my old DIY prusa but I might have to resurrect that to print this!
I thoroughly recommend building one (a Hadley). It really works, and it’s not expensive. And yes, it is fun. I haven’t had any of the problems you are concerned about, but the key point is that I could re-print any parts that degraded.
The main advantage of this design is that it’s Open Source. So, all of the dimensions are available, and new parts can be designed that fit perfectly with the others. I started with the stock eyepiece/focuser, but it’s not that good, so I moved on to an improved version (although I can’t remember the name).
My advice for anyone who is curious is to go right ahead and build one. The Moon looks fantastic, and I have seen Mars and Jupiter (and four moons) and some well-known star clusters. It’s just amazing, and I built it myself.
Hello, I’m Raph, the creator of the Smallest. Thank you very much for sharing the project, it’s really cool. I have modified the accessibility of the Readme file to make it straightforward.
You will want to hike or go to darker places with your compact telescope, but PLA will deform if left in a moderately hot car.
Thanks for dropping in! And thanks for clarifying the reason for “no PLA”. I think you should add this to the description on the website. When anyone makes such blanket statements without any context or explanation others start to get suspicious, and want to know why. I suggest “DO NOT print with PLA – it will deform if you leave the telescope in a hot car”. Then it’s up to others to heed the warning, or not, but for the right reasons.
I printed my Hadley with PLA. I am careful not to leave it in a hot car, or other excessively hot environment. I haven’t noticed any creep, but it’s fully adjustable, so it can be realigned at any time. It’s certainly not going to change shape over a few hours.
I ground my own 8 inch (200mm) f/5 mirror when I was 15 and the Mirror kit came from Edmund Scientific Co. I was fortunate that I was a member of the Los Angeles Astronomical Society where I received guidance and help with the final figuring. An F/5 requires a deep parabola before you polish the final shape. One of the LA Astronomical advisors was Tom Cave, a very well known optician and owner of Cave Astronomical Scopes. After 50 yrs, I still use and enjoy my scope. I own more modern scopes, an SCT and two APO refractors for imaging. My 8″ F/5 was made into a truss Telescope for portability and most of the truss blocks both upper and lower were 3d printed in PA6-CF as well as small parts used in the build. I agree, no standard PLA, but if you used HT PLA by Polymaker (150C) heat-resistant, they guarantee it will not warp up to 150C. However, in the literature it does not mention its UV resistance, therefore, I would not consider it for the build.
I swear hackaday installed a tracker on my PC.
I’ve been searching stuff like this the past week. And multiple other occurrences of articles on the exact topic I’m looking into all the time🤣
Curation algorithms have expanded beyond specific sites… I also find stuff from my niche suddenly popping up all over the place, and it’s because the people running those sites are getting the same stuff fed to them by the same pile of algorithmically-curated social media dumps.
It really does eventually create a creepy hivemind effect, as people have noticed for almost twenty years now at least
There is a link at the top of the printable page with the README and BOM.