3D printable 6" f/5 compact travel telescope model
17 comments
·June 16, 2025chantepierre
Hello HN,
A friend released files for this 6" f/5 telescope conversion kit yesterday.
It is a synthesis of a lot of telescope builds he, I and a few friends made over the last years, as well as general ideas floating in the amateur telescope making community.
It is compatible with most existing 6" f/5 newtonian optics kits. I've tried his model IRL and was pleased with both the movements and the focuser, which is often lacking on commercial offerings (which are also heavier and bulkier).
Unmounted, it forms a quite compact package to hike with or take camping.
It is licensed under CC-BY-NC-SA as he would like to sell parts kit at some point, but the files found on Printables are fully functional.
addandsubtract
Do you have any recommendations which optics kits to get and where to get them (preferably available to the EU)? What about a good budget entry eyepiece?
chantepierre
For budget entry eyepieces, the generic "goldline" eyepieces have pretty good bang for their buck, especially the 9mm/6mm ones. You can find them unbranded online, or the "redline" equivalents.
I'd recommend a quality 20/25mm plossl rather than the gold/red line 15/20mm that display a lot of issues.
For better eyepieces, at f/5, the rubber-top generic eyepieces with color bands sometimes branded as "artesky" are great for their prices too.
If you have a bit more budget, Explore Scientific is generally the overall best quality/price ratio. Avoid baader hyperions, except for the 13mm which hits above its price (second-hand)
chantepierre
6" f/5 kits sold by GSO are okay, but the best choice is to find any second-hand skywatcher 6" f/5 tube on your leboncoin/craigslist equivalent and scavenge the optics. For industrial optics, they are on average exceptionnally smooth and have a good shape with few defects.
The 6" f/5 optics kit are a bit of an oddity, those we test with our interferometers are consistently good, whereas smaller or bigger diameters are subject to a lot more vatiations.
tanvach
I’ve just been looking for a telescope that’s backpackable. Thank you for posting this!
jxjnskkzxxhx
Slightly OT: how fragile are 3D printed things? Do they break easily? Do they feel fragile? The rods in thi design, might a person break them by accident? How about intentionally?
hengheng
Really depends on what material you're pushing.
PLA is not strong and doesn't like to warm up in the sun, Silk PLA (made to just look nice on the shelf) can even be brittle. But there are better materials.
PETG is entirely reasonable, I store my pots and pans on PETG hooks and they're not oversized. The superior 3d printers can print ABS which is above any and all doubt.
There are also specialized materials, such as carbon infused PETG, and there are engineering materials at 500€/kg with some interesting properties. But the gist is that PLA makes you go "this sucks, must be printed", and PETG makes you go "oh this is fine".
Then there are resin printers that selectively UV cure a liquid to polymerize it. Last I tried that sticky goo it was awfully brittle and borderline unusuable. I heard it improved, but that's why resin printing is not everyday parts but figurines.
ffaser5gxlsll
Regular PLA is actually stiffer than PETG/ABS, but it's more brittle (so has less impact strength) and a pure formulation has a lower softening temperature. It's generally not suitable for parts that go under the sun, unless it's some other formulation such as some HT-PLA variant, in which case it's actually a good choice for parts that need to be thin and stiff.
Under most cases, you won't get the same inter-layer adhesion with ABS, so while you get better impact resistance, under most circumstances PETG will yield more durable parts that won't delaminate under the same stress conditions. For outside use under the sun, you should use it's cousin ASA.
To respond to the OP.. 3D printed parts can be incredibly durable when printed correctly. The parts need to be designed for 3d-printing in mind, like most other manufacturing methods. A 1cm-thick 15% filled PLA slab that has been printed vertically might be easy to snap in half with two hands, but it becomes almost impossible to break with bare hands when printed horizontal, and requires a saw to be cut when filled to 50%+. And this using consumer-grade printers.
I'm using 3d-printed parts for work and at home, some in use for almost 7 years at this point, and the only telltale sign is the layered look.
The rods in the design are not 3d-printed, which makes sense (most plastics would be too flexible, and 3d-printing a rod is always more expensive).
jopsen
I've often found PLA to be fine. But small features on a large part can break if dropped.
Of course it all depends on you application.
ethan_smith
The durability depends entirely on print settings (infill percentage, layer height), material choice (PLA, PETG, ABS), and load direction (perpendicular to layers is weakest), but properly printed PETG or ABS parts with 25%+ infill can be surprisingly robust for functional parts like telescope components.
chantepierre
The rods are heatshrink tubing wrapped-aluminum. I personnally have built a few partially 3d printed, or full 3d printed (except for a few hardware items and carbon fiber rods) telescopes – it all depends on print preparation skill, correctly drawing for 3d printing, and wise choice of material and print conditions.
javchz
Depends on the material and settings. But for example PETG it's as strong as a water bottle.
filcuk
That can be a bit misleading, I feel. It depends on how well the layers are fused together, post-processing, or even the orientation of the print. At best, it can be nearly as strong as a water bottle, but I wouldn't expect it to be.
wickedsight
According to the description, the rods are aluminum. Printing rods this long is near impossible and if it was, they definitely wouldn't be rigid enough for this application.
To answer your main question, it depends. There are many materials you can print with, they're strength can differ greatly. Some are very rigid, but somewhat brittle, others are less rigid, but also less brittle.
Then it also depends on the design, the video[0] below is a great video on designing for 3d printing and the considerations needed for strength.
Finally, print settings matter. Temperature can affect layer adhesion. Infill and wall count can affect strength and so can print direction (see video).
3D prints can be pretty strong though. I'm using 3d printed mounts to hang snowboards on my wall, for example. I've printed plenty of other stuff I really couldn't print by hand. And I'm only using FDM printing, with SLA and SLS printing even stronger parts can be printed.
incomingpain
I 3d printed the 114 hadley telescope years back.
Saturn and Jupiter were easy, but not super clear. Mars was maybe just out of reach even on good nights.
This 6 inch will likely be perfect. Very clever design as well!
chantepierre
The Hadley is the perfect gateway to telescope building.
A 6" packs a lot more punch in a not too much bigger package, and 6" f/5 consumer mirror kits that we test often range from okay (0.77+ strehl) to actually quite good (around 0.92).
You'd get quite an improvement on planets !
TIL Bahtinov Mask
https://en.m.wikipedia.org/wiki/Bahtinov_mask
That’s a clever device for focusing a small scope.