Stripping 3D Printed Gears for Science

While 3D printing is now well on its way to becoming “boring” in the same way that a table saw or lathe is, there was a time when the media and even some early adopters would have told you that the average desktop 3D printer was perhaps only a few decades behind the kind of replicator technology we saw on the Enterprise. But as the availability of these machines increased and more people got to see one up close, reality sunk in pretty quickly.

Many have dismissed the technology as little more than a novelty, and even within the 3D printing community itself there’s a feeling that most printers are used for little more than producing “dust collectors”. Some would see this attitude as disheartening, but the hackers over at [Gear Down For What?] see it as a challenge. They’ve made it their mission to push printed parts to increasingly ridiculous heights to show just what the technology is capable of, and in their latest entry, set out to push a pair of 3D printed gearboxes to failure.

The video starts out with a head to head challenge between two of their self-designed gearboxes. As they were spun up with battery powered drills, the smaller of the two quickly gave up the ghost, stripping out at 228 lbs. The victor of the first round then went on to pull a static load, only to eventually max out the scale at an impressive 680 lbs.

The gearbox may have defeated the scale, but the goal of the experiment was to run it to failure. By rigging up a compound pulley arrangement, they were able to double the amount of force their scale could detect. With this increased capacity the gearbox was then run up to an astonishing 1,000 lbs before it started to slip.

But perhaps the most impressive: after they got the gearbox disassembled, it was discovered that only a single planet gear out of the ten had broken. Even then, judging by how the gear sheared, the issue was more likely due to poor layer adhesion during printing than from stress alone. No gears were stripped, and in fact no visible damage was seen anywhere in the mechanism. The team is currently unable to explain the failure, other than to say that the stresses may have been so great that the plastic deformed enough that the gears were no longer meshed tightly.

This isn’t the first time we’ve checked in with the team at [Gear Down For What?], just a few months ago they impressed us by lifting an anvil with one of their printed mechanisms. They’re also not the only ones curious to find out just how far 3D printed plastic can go.

[Thanks to Nils Hitze for the tip.]

33 thoughts on “Stripping 3D Printed Gears for Science

      1. Why irrelevant? Making it obscure to ca. 90% of the world population by using idiotic units that are only used in USA and Liberia seems quite silly. The complaint is not. HaD editors/posters could EASILY solve the issue by doing a simple unit conversion here and there. There is no excuse for laziness.

        1. By your own admission, you spent more effort writing your whiny post than you would have to make the conversion your self. HaD reported the story with facts as they occurred. That is not laziness. That is called good journalism, and it’s lacking in modern history.

          HaD reports units in the manner that they were acquired (at least most of the time). If you want a different unit, do the conversion your self. If you don’t know how to do the conversion, WolframAlpha can help. If you can’t be bothered to do that – keep your mouth shut. This applies to metric and imperial users equally.

          1. This is the real answer here.

            Of course it comes up from time to time if we should be converting everything on the site to metric. Even though the US is the single largest contributor of traffic to the site, we naturally have readers from all over the world where these units may not immediately be recognizable to them.

            But at the end of the day, we pass on the information that we get from the source. The original work was done in US units, so that is what is repeated here for the sake of clarity. Had the creator of the video given his measurements in KG I would have used that instead.

            In which case, naturally, we would likely be seeing the inverse of this complaint.

      1. Fake Future News: Hackaday accused of patronising readers when it does full metric/imperial conversions of all units mentioned. Readers say “It’s like they think we can’t do grade 5 math.”

          1. I see the phrase as a compromise, I think most people in the US would have written “5th grade math” and English speakers in most of the rest of the world would have written “grade 5 maths” :)

  1. man, i imagine i’m not the only one here who only prints custom things, and uses the hell out of what he prints. i mean, project enclosures alone…and household doodads…and toys for the kids. very pleased with my 3d printer. not gathering dust at all.

    1. I think it is more the dilettantes who thought they could just visit a free online catalog like thingiverse and make unlimited cool stuff a 3D printer gets lame-o pretty fast.
      But when you are making stuff that you cant buy and have designed specifically for your purpose it is almost irreplaceable at least for prototype stage and is cheaper and most often way faster than throwing a block of whatever at a CNC machine and carving it down way faster than making an injection mold.

    2. I think that one of the under-appreciated uses for 3D printed models is the representation of data. Before my retirement I headed a group in our large pharmaceutical company and brought in color 3D printing while it was still in its infancy. We made 3d models of all sorts of things, biomolecules, membrane structures, viruses, process optimization data etc. Often discussions with colleagues and management were greatly improved by having a 3d model of the thing (or things) under discussion, I can remember one case where the president of the division hopped on a plane and spent a few million dollars to buy a company that had been collaborating with us because he FINALLY understood the value of the relationship.

      1. Is it just the ‘wow’ factor for the marketing team in multi-million dollar deals that’s enough to justify the comparatively small investment for the company?
        Perhaps they need to be seen to be fully appreciated but what does a 3d printed pharmaceutical model convey that ball and stick kits (at considerably less investment) available for decades don’t?

    1. Its not longevity that’s an issue, it’s plastic creep which will set on within minutes of you actually lifting anything with a winch made entirely of plastic.

      Lift and engine block and leave it hanging, and half-an-hour later you won’t be able to wind it down anymore because the gearboxs has gone pear shaped.

      1. A couple solutions:
        1) Anneal the plastic (PLA works especially well with this, since it also solves the main issue with PLA: it’ll deform in a hot car or hot water). This will distort it a bit, but that’s fine for some objects, and it’s possible to compensate for it if you take this into account.
        2) Use a filled plastic. This reduces creep but can make things more brittle.
        3) Simply operate with a healthy margin of safety.

    1. Yeah, wifes and their opinions. Classic.

      I used to have an ’06 Impreza, bought it before i even knew my now-wife. She didn’t like it too much. It was ok and she did get to be driven around in it, but said it was impractical. Right up until it got wrecked – screw you, people that use phones at the wheel – and i bought a ’00 Forester. That’s when she started missing the ‘preza.

    2. hmm… perhaps I’m the lucky one, mine didn’t complain when I build one and she didn’t complain when I printed 2 replacement shower curtain rings (my first successful print). Now I’ve rebuild my printer into a better one, she still doesn’t complain about the device, it’s smell or presence. Only the noise, she did complain about that once, and to be honest, she was right. Those stepper motors (even with heavy micro-stepping) can produce loud and anoying sounds, because most of the sound was contact noise, you could hear it through the entire house (if you put your ears against the wall. I could eliminate that by placing the entire printer on an inflated bicycle tire (inner-tube only). The printer now can only be heard in the room and the wife is happy again.

      PS: force/load in lbs, kilo, stones or elephants is non-scientific, just use Newtons, these are accepted world-wide (or at least in my world).

      1. “…she didn’t complain when I printed 2 replacement shower curtain rings…”

        Initially the 3D printer is seen as a toy…
        Typically the first prints are little more than figurines to test it out.

        But when you use it to print something that makes their lives better,
        shower curtain rings in your case, faux candle sticks in mine.

        Then they view the 3D printer as a tool, not a toy. ;)

  2. I’ve printed outlet covers, drink openers (of course!), a tool for removing the fuel pump to help me fix my car, curtain rod holders, key chain holders, some kid-resistant cabinet locks (ended up designing them myself after kids broke the ones from thingiverse), baskets for odds and ends, all sorts of toys for the kids, am currently working on a drainage/irrigation system for my garden and a greenhouse frame, and a bunch of things I can’t even remember. There are lots of fairly practical things you can print.

  3. I don’t think I’ve ever printed out a non-function object with my printer. I’ve made many many drones out of it, mechanisms, shrouds, cases.. You’d be amazed at what a printer is capable of when you use the parts correctly and design them correctly, IE: Factor in the grain of the print, design to avoid overhangs that are too steep, memorize how the printer messes up dimensions and pre-scale features in the part so they are dead on when it prints, etc. I have made incredibly complex parts, and jigs for welded parts and assembled parts, with my printer. I love abusing its patience and love of accuracy so I don’t have to sit there and drill a bunch of holes or line a bunch of parts up, when it can instead. Make it work for me, not against me. ;)

  4. Wear is a huge factor in any geared system however saying that a process I have been recently playing around with is nickel plating plastic components. I have not yet tried it on a gearing system but given that nickel has a really high resistance to wear and the plating process creates a really hard surface its tempting to try it out.

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