I made a 3d printed nut and bolt sorting machine

I got tired of having frisbees filled with unsorted screws at the end of every build day. So I designed a screw sorting machine. It’s a flexure based design you can print out of PLA.

Part 1 gif
Part 2
Yes, it also works on imperial.
Assembly animation


That is awesome! Does it work well in practice?


In limited testing it has seen so far, so good. That said, flat head screws have a tendency to want to get jammed in between the rods at the far edges but if you don’t give it a ton of screws at once it works fine. A bunch of fixed width sieves for just the sizes you use are for sure way more practical but this is cooler and works on almost everything.

I love seeing these kinds of projects, keep up the great work!


This is awesome! Great Job! Hmmm, now if you can make one to sort by length? :sunglasses:

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The gifs are very hard to follow. However, the YT video linked from the prusa page effectively explains how well this machine works.

Start of demo

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Not willing to build it, but just line up the screws of a given thread size all parallel and use an oriented sieve for sorting short to long progressively. Or present each one using a robotic arm to a camera for visual sorting. That I’d like to see!

That’s super cool. I am still a little worried about performance with mixed Socket / Button head fasteners, but I’m sure it would still be useful.

Maybe the next step is to include strong magnets so you can sort by length, similar to this Nail aligner / packager machine:


Separating socket from button and flathead of the same size is tricky for anything smaller than M4 (number 8) screws but if you’re not trying to pick out specific head types it handles a mixture just fine. I’m evaluating different design concepts for a printed length sorting design but that will have to come later as I have another project that will be higher priority for the next few weeks. Although I love magnets in things, for this I would kinda like to avoid magnets for a variety of reasons:

  1. Doesn’t work so well on many stainless steel alloys
  2. Works too well on many steel alloys — turns them into weak magnets that attract steel shavings from the far corners of the shop unless they are demagnetized with an alternating electromagnet or similar
  3. Makes the design now require power if an electromagnet OR an abundance of rare earth magnets which can become sort of pricey if you need N52 grade

Initial idea is to do something like a coin sorting tower but make the path the screws travel along helical so the overall design is more compact and can fit in a normal print volume. I want it to support 6-10 length selections and support diameters M2-M12 with flat, button, and socket head types supported. I also want the length selections easily interchangeable for metric and imperial standards. I haven’t designed anything so far though. Just tossing ideas around.

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Or the ultimate challenge: Separating 10-32 from 10-24.


When the diameter is exactly the same it sounds like a good application for an optical (IE robotic sorter) as the total effort expended on that route I imagine would be much less than with a pure mechanical solution. In practice, if you already have a bin of assorted same diameter screws, the difference is visually and tactilely quite large and it’s quick enough to just manually separate course from fine screws. Of course, industrial contexts that deal with more screws than FRC may warrant more automated solutions and it’d still be a fun project someone…just not me.

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