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3D printable 6" f/5 compact travel telescope model
- chantepierre 1y agoHello 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 1y agoDo 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 1y ago6" 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.
- addandsubtract 1y agoIf buying a used skywatcher dobson is the best way to get good optics, wouldn't I, as a beginner, be better off just using that dobson instead of going the DIY route? Is the DIY telescope only better for portability, or are there other advantages to building it?
- chantepierre 1y agoThe 6" f/5 can often be found cheap and without a mount, but if you are beginning, absolutely find some secondhand dobson before going DIY. Or better : attend a few nights at a nearby astronomy club, that will allow you to get a feel of the practice, what you can see, what you should expect... Depending on your location (city? middle of nowhere?) and willingness to drive to darker skies some types of instruments and targets are better than others. This kind of kit is focused on being compact and lightweight, but that can be an advantage or a non-goal depending on what you want to do.
- chantepierre 1y agoFor 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)
- dylan604 1y agoSince this is hand tracked, how's the feel of the movement while tracking or slewing in general?
- chantepierre 1y agoDobsonian mounts are made to feel great and work with friction between (here) plastic and teflon pads, both in the altitude and azimuth axis. The goal is to have your telescope properly balanced so there is no need to apply force to hold it in position, nor need more force to start a movement than to keep moving, which would lead to jerky motion. Properly balanced, everything must feel smooth and easy.
- incomingpain 1y agoI 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 1y agoThe 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 !
- cchance 1y agoI've wanted to build one for a while, but seems theres not much info on the actual optics and which ones are worth getting do you have a list anywhere of where you had good results from?
- chantepierre 1y agoHey, I missed your comment. Nowadays the best source for optics is often a secondhand instrument where you scavenge the optics. If we specifically talk about a 6"f/5, most recent industrial tubes have really decent optics. Buying new optics online, avoid any ad where the price seems surprisingly low. For example you can find 6"f/5 mirrors advertised as lambda/8 precision. There's a lot of abuse with this denomination : some sellers use surface precision, whereas we usually talk about reflected wavefront, so lambda/8 becomes lambda/4. Then, there are a lot of ads for optics at great prices that aren't specified as parabolic (in the case of newtonian mirrors). Most often those are spherical, which is totally unsuitable except for longer focal ratios (and that quickly becomes impossible as diameter grows). On the other hand, I recently ordered a 40$ "lambda/8" spherical mirror, and it was a great sphere, so a great starting point to polish it to a parabola.
- tanvach 1y agoI’ve just been looking for a telescope that’s backpackable. Thank you for posting this!
- jxjnskkzxxhx 1y agoSlightly 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?
- ethan_smith 1y agoThe 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.
- wickedsight 1y agoAccording 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. 0: https://youtu.be/mziT7KV-fRI https://youtu.be/mziT7KV-fRI
- javchz 1y agoDepends on the material and settings. But for example PETG it's as strong as a water bottle.
- filcuk 1y agoThat 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.
- leetrout 1y agoTIL Bahtinov Mask https://en.m.wikipedia.org/wiki/Bahtinov_mask https://en.m.wikipedia.org/wiki/Bahtinov_mask That’s a clever device for focusing a small scope.
- ajsnigrutin 1y agoIs there some more info? What else do you need, other than a spool of not-PLA? How much does it cost? Where can you source the other materials?
- chantepierre 1y agoThere are a bit more information on his website [1] and I've made a temporary grouped BOM [2] : [1] https://la3emedim.fr/assets/SMALLEST%20-%20README.pdf [2] https://docs.google.com/spreadsheets/d/1XXZB4jRtvtlDIqlR69C0FRri8x8lZDpxO6ZGnSp3L2Y/view Basically anything but PLA will work, PETG will be the best difficulty/cost compromise.
- cchance 1y agoreally wish stuff like this was just all correlated on github or something so a community could easily grow for projects like this
- chantepierre 1y agoI'll push him to tidy this up :)
- mhb 1y agoWhy four sets of support struts?
- chantepierre 1y agoIt's a compromise between having a geometry that is rigid enough to ensure the bottom and top planes stay aligned while the telescope slews up and down, while having a practical shape at the bottom (a square) and avoiding struts going into the light path, which happens if you do an hexapod shape without making the base larger to compensate. Since his initial goal was to make this printable on an ender3 build plate, the smaller square shape was preferable.
- aquir 1y agoGreat build, but I can't find the README and what is the recommendation if it's not PLA? PETG? (I will give this a try with PLA-CF...)
- chantepierre 1y agoYeah his site isn't currently the clearest for that. Here's a direct link to his build instructions [1] and I've made a temporary by-item BOM [2] while he improves things. PETG is great, ASA and ABS might be better if you have the capacity. [1] https://la3emedim.fr/assets/SMALLEST%20-%20README.pdf [2] https://docs.google.com/spreadsheets/d/1XXZB4jRtvtlDIqlR69C0FRri8x8lZDpxO6ZGnSp3L2Y/view
- jakogut 1y agoWhat about glass or carbon fiber filled PA6?
- chantepierre 1y agoI don't have enough experience with nylon to assess whether it would be suitable for a full telescope, sorry.
- bb88 1y agoAll plastic is going to warp over time. So that probably seems like overkill unless you're planning on abusing it. That said, I would give PETG-CF a try. I've made parts with that and it's certainly been good, and is definitely better than PETG.
- seanthemon 1y agoPla-cf is generally more brittle because of poor layer adhesion due to the fact that carbon fibre doesn't stick to carbon fibre. Pla also doesn't need the additional stiffness CF provides so it's just a gimmicky filament. Petg is a better option.
- kube-system 1y ago
- tregoning 1y agoSeems very cool but all of the photos and videos I could find is about how to build it not the most important thing.. how good it is as an actual telescope how does the moon/stars etc look though it
- BenjiWiebe 1y agoThe actual view has little to do with the build of the telescope, and lots to do with whatever optics you put in it. The mechanical part can influence the view via "tube currents" (air flowing in the optical path due to heat convection) or by not allowing good heat flow to and from the mirror so it stabilizes quickly. There's a few more things to consider, but remember it's mostly the optics.
- tim-fan 1y agoDoesn't the mechanical part need to position the optics with a fair amount of precision to get a good view? Id imagine very slight movements or misadjustments could cause issues. I don't know much about telescopes :p
- chantepierre 1y agoYou need smooth movement on altitude and azimuth axes, then the telescope must be still and vibration-free to enjoy the view. The other constraint is structural integrity to maintain alignment of the optics. Those two things are the basis of all builds (except for optics!).
- petee 1y agoIt'd be great to hike with one; I've heard a some of the Appalachian Mountain Club huts have telescopes. On the subject of viewing targets, I unexpectedly found Globular Clusters to be really neat. As your eyes adjust, the stars just keep multiplying. And you can easily catch great looking photos.