3D Printed Mechanical Counter

[Music] thanks for dropping in if you follow me on twitter you know i've been working on a mysterious gear related project for the last month well today i finally get to show off the result this is a 3d printed counting mechanism and it's the first step to a larger project i have planned for tracking new year's resolutions this mechanism functions the same way a car odometer does well the ones that are mechanical at least as the rightmost wheel rotates all the other wheels remain stationary until the exact moment the count carries over to a second digit if that second digit is also ready to carry over the movement transfers to a third wheel and a fourth and so on but how does this work it can't just be a series of ten to one ratio gears a setup like that would result in every gear moving slightly with each turn of the first wheel the result would be an illegible scramble of misaligned numbers the solution to this problem has been known for a long time as any old car odometer will attest but i never really gave much thought about it until i saw a series of youtube videos by matthias wendall where he creates a large wooden counting mechanism and breaks down how it works i will of course link to those in the video description because there's no way i can improve on his explanation so i just made a 3d printed version of matthias's design right wrong i had to make things a lot more difficult for myself most counting mechanisms you'll find are a series of numbered wheels that use external indexing wheels for reasons that will come later i needed all the parts for this mechanism to sit inside the counter itself see no wheel so the inside of this frame must be crammed with gears then right no once again my rhetorical questions have led you astray most of this mechanism is completely empty and the vast majority of what remains is there to provide structure not mechanical function this is one digit of the mechanical counter scaled up for the sake of this demonstration it's comprised of a single indexing gear this transfers motion between the wheels a stationary core which just holds everything together in a rotating exterior ring that's it as the wheel begins to rotate the indexing gear remains stationary this isn't just because nothing's pushing it around it's actually locked into place half the gear's teeth are taller than the rest and these taller teeth are unable to move over a short lip on the inside of the number wheel so the gear can't turn until that is we get to this part of the rotation a small gap opens up for the index wheel to roll into the gear is forced into a 90 degree rotation after which it will once again be locked into place let's talk about printing this thing on one hand these parts are very printer friendly at least half of my time was spent removing overhangs and simplifying the shapes no supports are needed and what bridging remains is very minimal but these parts are very small and the clearances are by necessity very tight even minimal over extrusion rough seams or printer blobs will be a problem so if you plan on printing this i strongly recommend printing only a single layer one number ring one core and one index wheel to make sure the parts slide smoothly together if they do print one more layer and make sure those mesh together even though this is basically a prototype i've included a few different customization options the ring comes in three types a simple number ring which you've already seen a control ring which has a grippy surface that you can use as your input and a combination number and control ring with the two parts merged together if you use a control ring the counter will only go up every full rotation of that ring this is great for well control in how quickly the counter advances the combination ring on the other hand translates that movement directly into the first digit so that's ten times faster by default the core has three millimeter holes that you can use to bolt the layers together but i also have an alternate glue version that doesn't have those holes at all if you're making a very small counter only two or three digits the glue version is probably fine but anything longer than that really should use the bolt option it helps eliminate any wobbling in the assembled counter i hadn't mentioned them until now but this design also has start and end caps and those are available both enclosed and open variations the closed option gives you yet another bolt hole to hold everything together the open option of course gives you a view into the mostly empty interior of the counter there's also this optional drive gear use this if you want to hook the counter up to a motor every full rotation of the drive gear will advance this wheel by four if you want to test this design to the limits and possibly end up with a broken counter this is the fastest way to do that use caution and expect to smell plastic some of you are probably wondering how long can this thing get [Music] well let's find out now i've got a lot of extra parts in 150 millimeters of m3 threaded rod for this assembly i'm going to build this bottom up that is to say starting with the initial counting digit the first thing that goes on each layer is the wheel it should sit on the surface of the previous layer or in this case the starting cap and it should rotate freely [Music] next add the core these two spots on the bottom should line up with two pegs on the previous layer make sure you line it up so that the portion of the wall that's open this part right here lines up with the portion of the wall that's open in the previous layer like that next we're going to add the indexing gear one side of the gear is completely flat but the other side has teeth at different elevations this side is going to be face down and it connects on this little peg right here when you place the gear on it needs to be rotated so that way it falls into the spot and you'll know that it's correct if you can rotate the outer gear and have it advance as expected before going on to the next layer i'm going to move this ring so that it's engaged with the indexing gear like so the gear is right between nine and zero as i build up the layers i want to be able to test advancing the gear forward one and back one so if everything's working right it will go from zero zero zero zero zero to nine nine nine nine nine without any significant problems now i'm just going to take the next ring and continue this process all the way up the counter because i intend to turn this into several smaller counters later i'm only using a single threaded rod to hold this whole assembly together regardless of whether you use glue one threaded rod or three threaded rods don't force the layers together too tightly that can bind up the mechanism all right we're out of threaded rod if we include the actual rollover that means that this counter can reach one billion at one rotation per second that's over 30 years so i'm obviously not going to be able to test that fully but what i can do is check the last rollover which engages every single index gear in the device so we are currently at 999.94 and if we increase that slowly all the way to nine and there we are zero zero zero zero zero one now um something you'll notice is as the length of the device gets longer there's a gentle slope that's introduced in these numbers not so much that you can't easily read it but it's definitely there and if you're familiar with the actual odometer meters in cars they tend to do this too although not as obvious because the clearances involved for a 3d printed part are just so much larger than the injection molded gears that you would find in a car odometer but it does work i also can't say for sure whether or not this would be easier or more difficult if you were to scale up the design on one hand the clearances would definitely be more forgiving but that slope issue i was describing would also increase so is that a good enough trade-off i don't know if you are not counting up to a billion having that extra slop probably wouldn't be that big a deal this isn't the last you're going to see of this mechanism but i think even this prototype was fun to build and i learned a few things even on this assembly for this video for example don't max out your threaded rod it means that you can't actually fully tighten the device in the end and that's making this feel a lot more sloppy so until next time happy printing and thanks for stopping by [Music] you

Channel: 3D Printy

Views: 1,088

Keywords: 3D Printed, 3D Printing, Mechanical, Counter, Mechanism, Gears, Fidget

Id: M1kdm8jpN80

Length: 10min 20sec (620 seconds)

Published: Mon Dec 20 2021