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Extreme Reduction Gearing Device Offers an Amazing Gear Ratio 148

ErnieKey writes: The 3D printed extreme reduction gearing device, created by long-time puzzle maker M. Oskar van Deventer, may leave you puzzled for its obvious applications, but the coaxial cranking mechanism offers potential in a variety of real-world applications with multi-colored gears that move in opposite directions at a ratio of 11,373,076 : 1. This 3D printed reduction gearing device is compact and multi-colored, and looks deceivingly simple at first glance. Developed through a complex algorithm, it could possibly offer potential as parts for machines like 3D printers, aerospace and automotive components, as well as perhaps robotics and a variety of motors.
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Extreme Reduction Gearing Device Offers an Amazing Gear Ratio

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  • it could... (Score:5, Insightful)

    by drinkypoo ( 153816 ) <> on Tuesday July 07, 2015 @12:34AM (#50060257) Homepage Journal

    it could possibly offer potential as parts for machines like 3D printers, aerospace and automotive components, as well as perhaps robotics and a variety of motors.

    Correct me if I'm wrong, but wouldn't that much reduction be fairly pointless? Wouldn't you basically have to make it out of unobtainium (the high-torque parts, anyway... most of it, that is) in order to do useful work with it?

    • Yeah, I don't see a practical application for this. You don't need that high of a ratio for any serious applications that don't also undergo tons of stress.

      • It would be a good test of internal stress. But there are so many directional stresses, it would probably be best for something claiming to be the best in most directions.

        Requires a lot of further testing, but this would probably eliminate the early ideas.

      • by kcelery ( 410487 )

        Print the gears,
        Connect the crank shaft to a 9 volt battery motor.
        Connect the slow side of the gear to a simple block that pulls a rope.
        Take the gear to second floor, connect the rope to a frig or washing machine.
        Make a video of lifting a frig with 9v battery, put it on Youtube and become famous.

        • Re:it could... (Score:4, Insightful)

          by Anonymous Coward on Tuesday July 07, 2015 @02:52AM (#50060623)

          The weight of the fridge, transferred via the rope and pully, will rip the gears clear off the end of the shaft and tear this 3D printed device apart.

          As the GP was getting to, the multiplicative effect of the gearing on the torque is only useful if the structural strength is there to match.

          A car analogy applies to rev heads fitting low-geared diffs and transmissions to their cars, to only find they do stupid things like twist the chassis out of shape or rip bearings or thrust spindles apart!

          • Re:it could... (Score:4, Informative)

            by donscarletti ( 569232 ) on Tuesday July 07, 2015 @04:11AM (#50060845)

            The weight of the fridge, transferred via the rope and pully, will rip the gears clear off the end of the shaft and tear this 3D printed device apart.

            I think the point of the grandparent is that the torque caused by a fridge dangling from a rope is far from extreme, a 100kg fridge on a rope wound on a 0.5m diameter capstan would exert 245Nm of torque onto the axle, less than the engine from a standard family car does before reduction gearing.

            While that little hand held plastic toy might not handle the stress, if you were to scale it up or 3d print it out of metal (as some newer 3d printers can do) it would handle it easily.

            The point of the 9v winching example is not that a fridge exerts a lot of torque onto the capstan, it is that a battery driven electric motor exerts so little.

            • Re: (Score:3, Insightful)

              The 9v battery would have to be changed very frequently.

              Anyway '9v battery' analogies and references are now obsolete. Have you noticed how expensive those freaking things are now? All modern designs have switched to batteries made out of a few AA cells.

              • by jfengel ( 409917 )

                Well, lessee... a bit of Googling says that your average 9V will have about 15 to 20 kJ. Let's go with the high number.

                For a 100 kg fridge, if I'm doing the math correctly, that comes out to 20 meters. Not bad, actually. Or 15 meters for the low end.

                Of course you can't really get that kind of efficiency, I'm sure. And 100 kg is actually a pretty light fridge. But it's actually not completely out of the realm of possibility.

                (Unless I've screwed up the math, which is entirely possible.)

                • by KGIII ( 973947 )

                  Just switch the fridge out for a keg. It will net the same number of viewers and possibly more. You could also try lifting up a pig and processing it into bacon. That might just win the entire internet.

            • a rope wound on a 0.5m diameter capstan

              You pick up 0.5 m diameter capstans on reguar brasis?

          • Or maybe the real advantage lies not with torque multiplication, but reduction of movement.

            Precise angular displacements of down to a billionth of a degree, at a scale you don't need an electron microscope to see.

            • by Anonymous Coward

              The [lack of] precision in the bearings is much more significant than angular precision.

              A good quality stepper motor can achieve the slow angular velocity you are after, and a "normal" reduction (10000:1 or so is commonly availble) via a regular gearbox will do the rest.

              • Re:it could... (Score:5, Interesting)

                by Smidge204 ( 605297 ) on Tuesday July 07, 2015 @06:09AM (#50061201) Journal

                The [lack of] precision in the bearings is much more significant than angular precision.

                You solve that with better manufacturing techniques.

                Harmonic drives are already used industrially and commercially. This is essentially a double harmonic drive driven with a planetary gearset. Nothing some good precision manufacturing couldn't create something amazing with.

      • by TheCarp ( 96830 )

        Everyone is so stuck on the maximum ratio. I think the point is the mechanism has interesting properties and is quite small. Looking at his materials, he lists several gearing configuratios including output reductions of ~2, 87, 1000

        That plus its ability to hold its output load, and do it all so compactly with so few parts makes for a more intetesting device than just the maximum output set he printed.

      • How about fine-grained telescope/antenna rotation to track stars across the sky as they move for (radio-)astronomy. You'd or course need a complement mechanism for the elevation.

    • Re:it could... (Score:5, Insightful)

      by serbanp ( 139486 ) on Tuesday July 07, 2015 @01:24AM (#50060407)

      I once built an extreme gear reduction (3600rpm to 0.1rpd - d stands for "day") using ordinary plastic gears. The target use was to demonstrate pulling a salt mono-crystal from a saturated salt solution. No high torque, just a veeeery slow motion needed.

      • Re:it could... (Score:4, Interesting)

        by Hadlock ( 143607 ) on Tuesday July 07, 2015 @06:39AM (#50061287) Homepage Journal

        Is there a video/paper on this experiment? Sounds interesting. How big is the resulting crystal?

        • by serbanp ( 139486 )

          I did it together with my (then) 9yo, after he became interested in crystals (he got as a present some sort of "crystal science" kit).

          The contraption operated for 2 days, after which I messed it up trying to add some water to the solution. At that time the crystal was about 15mm long (and not really a monocrystal, as I was hoping).

          The gear box is still around somewhere, gathering dust. Maybe I'll try again when the little one reaches a similar age. In the meanwhile, I learned how to do time lapse photograph

    • This demonstrates that you can have any gear ratio you want, in the palm of your hand. UP TO 11 million : 1. It's essentially unlimited.

      You may have dealt with some problems related to the 2GB or 2TB disk size limits in Windows and MBR. At the same time, other people had storage systems which would support up to 8 petabytes, or even exabytes. Exabyte storage volumes didn't actually exist, so one could say the large disk formats had no practical application, but the practical application was that it was

      • by Anonymous Coward

        I see this the same way - it demonstrates a design that has practically unlimited ratio.

        Except theoretically it is quite clear you can keep adding gears, and as there is no limit to how large you can multiply numbers by, there is no theoretical limit to how much gear reduction you could do. And you could easily make something much smaller than this if just trying to create some theoretical illustration, as a couple of credit card sized reducing gears would give you something with the same theoretical reduction ratio that you could lose in a crack in the floor.

        As far as demonstrating practical

    • by Kokuyo ( 549451 )

      Unless I have an error in my understanding of physics, I don't see the main application in moving big weights or anything of the sort. I'm thinking of another thing: Precision.

      I'm not really all that well versed in electric motors but isn't the precision of an electric motor dependent on how precise the bursts of current are applied to it? I am assuming that any electric motor has a set minimal step it must take... well, now you can up the precision by a factor of 11 million. Or you can use a much, much les

      • Stepper motors have a minimum step, based on the construction of the motor, though many designs permit some fractional stepping. A "regular" electric motor doesn't move in steps, but become imprecise when the amount of force applied is small in relation to internal friction forces.

        It's also a function of the machining tolerance of the parts and of the design, including issues of gear backlash - the dead zone that results from a change of direction, where all the looseness of fit in one direction is released

      • > I'm not really all that well versed in electric motors but isn't the precision of an electric motor dependent on how precise the bursts of current are applied to it? I am assuming that any electric motor has a set minimal step it must take..

        No, for tasks which require controlling the position or rate of rotation, the precision is NOt dependent on how precise the bursts of current are. You used the magic word there, "step". If you want to control the rotation of a motor with any precision, you use a

        • ... continued (Score:4, Interesting)

          by raymorris ( 2726007 ) on Tuesday July 07, 2015 @04:07AM (#50060831) Journal

          My browser submitted the post before I was done writing it.

          Distributing those pulses to the different windings has to be done externally, via transistors or other controlling electronics. So the pulses don't need precision timing or anything, you just have to count them.

          On the other hand, stepper motors can only have a certain number of steps per revolution (64 steps is a typical example, but other values are available) . So if you want something like 1/1000th turn, you do need a gear or screw of some sort.

          For very slow rotation, such as clocks, synchronous motors are normally used. They use the ac swing from positive to negative rather than a commutator. They're quite accurate, and used to be more so, because the ac supply is regulated to exactly 60 hertz in order to allow power companies to interconnect. Again you don't have to deal with any intricate control of the pulses, just count the number of swings from positive to negative and back. The precision of the 60 hertz ac rate was recently reduced in the US, but it's still precise enough for most purposes.

          • by Kokuyo ( 549451 )

            But that still implies that for highly precise operations, you'd need to build either a stepper motor with a lot of steps per revolution or you have to make absolutely sure that the frequenzy you apply is precise.

            To my thinking, with such a gear ratio you'd need only a 11 millionth of the precision on the motor side to reach the same outcome or, converesely, you achieve 11 million times the precision of the motor you use. Of course, it would be really, really slow, but for tiny applications? You could attac

            • by bbn ( 172659 )

              You assume the gears have no imperfections. You will find that it is not actually giving you the expected accuracy. Just a little bit of slack in the final gear could equal thousands of revolutions in the input gear.

          • Not even close in the US. UK and Europe count the cycles and try to average 60 Hz over minutes/hours/day with minor adjustments. The US has massive drift and variability.

            • My local power company has four generators, wired together to provide power for the city. They are connected into a regional grid with hundreds of other generators, but to make it simple to understand ignore those and just think about the four generators which are right next to each other . What do you think happens if one generator is trying to push the grid positive while another is trying to push it negative? That doesn't work out to well, so all the generators have to be in sync to within a few mil

    • by Ashtead ( 654610 )

      The closest I can think of when it comes to real-world devices that have a large reduction ratio, would be something like the mechanical tachometer/hour counter combinations seen on old tractors and similar -- where the dial indicates something like "hours at 1500 RPM". That makes for a reduction rate of 900000 from the engine shaft to the rightmost wheel of the counting device if that were to rotate once per 10 hours.

      But in these, the reduction would be done via several stages of worm-drives, and the redu

    • by bbn ( 172659 )

      You need torque to turn this thing. Due to the extreme reduction, the needed torque has little if any relation to what you put at the output. Instead it is just the internal friction of the plastic gears. Which means there is a point where further reduction does not make it any easier to turn.

      You need strength in the part to use the output torque. Due to the extreme reduction, output torque is practically limited only to the point where the plastic gears break. There is a point where further reduction does

    • It strikes me as more of a proof of concept. While this sort of ratio is probably not all that useful, it does demonstrate that essentially anything useful is also possible.
    • by DarkOx ( 621550 )

      I think it might be useful for applications like printing or engraving where it isn't necessary to put much load on the 'output shaft' the ability to make very very fine movements possibly much finer than any stepper or solenoid etc we can manufacture may be very useful.

    • by tlhIngan ( 30335 )

      Correct me if I'm wrong, but wouldn't that much reduction be fairly pointless? Wouldn't you basically have to make it out of unobtainium (the high-torque parts, anyway... most of it, that is) in order to do useful work with it?

      I think the point is it's a gearbox that's quite small for its reduction ratio. And to make it that small requires basically being unable to assemble it in the traditional fashion because there's a lot of gears that going about inside one another.

      To assemble a gearbox with that kind o

  • by Anonymous Coward on Tuesday July 07, 2015 @12:53AM (#50060307)

    It has a very specific meaning and the way it is used in this article is not it. Sorry, pet peeve.

    • by Nyall ( 646782 )

      Hard to judge. They might be using it incorrectly or they might be using it in context of what this device is. The overall gear ratio is achieved by feeding one gear stage into the next. Where each additional stage providing a further multiplication. That sounds like exponential growth to me.

  • TFA seems to conflate the ideas of speed ratio and force multiplication. That is only true if the mechanism is perfectly efficient. In practice some of the input force will instead be consumed opposing friction in the mechanism and the output force will be limited by the stretch of the parts. So the maximum force multiplication achived may be substantially lower than the speed ratio.

    To make a high ratio gearbox practical for force multiplication the low torque high speed parts need to be small to minimise friction while the low speed high torque parts need to be large to prevent them from breaking.

    To make it practical for accurate rotational positioning again the low speed parts need to be large, otherwise flexibility in those low speed parts will compromise the ability to accurately maintain position.

    • by the stretch of the parts

      Sorry typo, that should have said strength of the parts.

    • It's basically a couple of harmonic drives made with plastic. These can be practical and fairly strong as well as compact. I know of one use for one in the aerospace industry, which I probably should not post about(the use, not the gearbox).

      The metallic harmonic harmonic gearbox we are using works very well. It does not have such an extreme ration (I forget the exact ratio), but it is very strong and compact for what it does.

  • Missing something (Score:3, Informative)

    by BitZtream ( 692029 ) on Tuesday July 07, 2015 @01:19AM (#50060389)

    Other than being printed, what's the special part? What makes it different from every other transmission other that it has many gears and uses excessive/bad ratios between them that make the device worthless from a practical perspective.

    its got 5 tooth pinions FFS, that'd be so rough and wouldn't last any length of time under load ... And then he discovered that if repeatedly chain those gears you get larger ratios still.

    You can do the same thing with fewer worm gears and smoother operation.

    This isn't even a little bit new, he's just chained a bunch of gears and is using the inside of the circle rather than the outside.

    Someone show this guy a traditional automatic transmission or a newer CVD and watch his head explode. His gadget is pretty trivial, certainly nothing novel about it

    • Re: (Score:3, Insightful)

      by Anonymous Coward

      The "special" part is that it's 2 planetary sets driving a third acting as a coaxial differential, *not* a long chain of reductions.

    • by Required Snark ( 1702878 ) on Tuesday July 07, 2015 @02:32AM (#50060585)
      So if you're such a genius, what have you done recently that's as creative as this? (Sound of crickets...)

      Did you bother to look at the video and see how he worked out the gear ratios? With a relatively small number of gears he managed to have a one in the denominator of the ratio equation and at the same time he made the numerator be 11,373,076. A design with those properties doesn't leap off the page the first time you try it. It's really hard.

      He said it was compact for the extreme ratio. I'll bet if you tried to do something similar it would be a lot bigger, need a lot more gears, and might not even work. Care to prove me wrong? (Hint: no combination of worm gears comes even close.)

      You're just another Slashdot Pundit, living in your parents basement and sneering at people who get stuff done in order to make up for the fact that you're utterly useless. Anyone with a life would never make such a stupid comment.

      • Re:Missing something (Score:5, Informative)

        by BitZtream ( 692029 ) on Tuesday July 07, 2015 @07:37AM (#50061503)

        ... Everything I do is more creative than this. Just because you have no clue that this isn't impressive doesn't magically make it so.

        I know how it works, there is nothing new about it. The video doesn't demonstrate anything new or uncommon, the only uncommon part about it is that he used shitty ratios that would break the instant it wasn't free wheeling. You can not use 5 tooth pinions if you want to do anything more that a free wheeling toy.

        Hint: LOTS OF THINGS SMALLER CAN EASILY BEAT THAT RATIO GIVEN THE SAME CONSTRAINTS. Those things are just worthless in a lot of cases.

        Open up a old school watch. That's impressive. Then get back to me about how compact this thing is for its ratio. Combine any two hand wound mechanical wrist watches, just the gears between hours and seconds, your already at 1:12M, and many times more "compact"

        Get a clue before you make an ass out of yourself next time.

      • by Keick ( 252453 )

        Creative? Maybe. Revolutionary? No.

        Look, his toy is very neat but it uses ideas and designs that have been used since at least the 1960's. He has a planetary gear inside a harmonic drive, which looks to be driving a second planetary gear inside a 2nd harmonic drive.

        A typical planetary gear is good for 30:1, a harmonic anywhere from 200:1 to 300:1. [] []

        Taking the low numbers, 30*200*30*200 yields 36Million to 1.

        So his 11 mi

      • I've designed many gear trains for various devices. The reason this is useless is because you can't drive anything with it.

        Harmonic Drives have been around a long time. []

        The problem when you couple them together is you get more torque then the teeth can handle.

        The reason most gear trains are larger is because you are typically trying to do something useful like taking a small high speed motor and using the gears for a high torque low speed application. This requires large gea

    • This isn't even a little bit new, he's just chained a bunch of gears and is using the inside of the circle rather than the outside.

      I can hear the scoffing arrogance in your voice. It's also entertaining that you're wrong. The operation to me looks very much like a bunch of chained strain wave gears, but without the actual strain wave. It seems to be achieved using a inner gear smaller than the outer one so that a rotational offset can propagate round much like the strain wave.

    • Yes. It is like a Weston differential pulley, except with gears. [] I have not met this before, but I recognize what it is and how it works. I expect you found the Antykythera mechanism really obvious, and sneered at that too. Oh dear, oh dear...
    • Size is most notable - you could achieve the same ratio with a chain of screws or stacked gears loose on two shafts, but it would take up a lot more space.

      The plastic is too weak for use with serious force, but a variation of the design might find some application as a mechanical counter.

  • by Nonesuch ( 90847 ) on Tuesday July 07, 2015 @01:20AM (#50060393) Homepage Journal
    In the end, a slightly less impressive variation on "Machine with Concrete. []"'?
    • by dtmos ( 447842 ) *

      This was my thought, too. There is a hand-crankable version of the same thing in some hands-on museum in or around MIT that I visited some years ago. It's amusing to be able to crank the first gear in a chain as fast and as long as you like, with the final gear in the chain welded to the frame.

      • by muridae ( 966931 )

        I don't know about a hand crank version, but MIT did have a bunch of his works on display a few years ago. I had to do a spring break report for a new media art course, and my spring break happened to be a trip to Boston to see family. I stared at "Machine with Concrete" for a while, working out how long it would take to move the tip of a gear tooth one Planck length; assuming no backlash. Pre-loaded with backlash, that machine could go well past mankind's existence before the concrete felt any force.

        And I

    • "The final gear is fixed in a block of concrete. If it were free to turn, it would make a complete revolution in about two trillion years."

      I'm guessing that because of the amount of "play" in the gears, there will be no stress building up inside that concrete any time soon... amiright?

  • by Bruce Perens ( 3872 ) <> on Tuesday July 07, 2015 @01:25AM (#50060415) Homepage Journal

    This is a fun device that can show you what can be done with 3D printed plastic. That said, it's useless. It would be really cool if I could apply 1 pound of force to the crank, turn it a Million times, and have it apply a Million pounds of rotational force at the other end. But it's made of plastic, so it won't do that. Indeed, the fast-rotating parts would wear out before the slow-rotating part made a single turn. So it's not even good as a kind of clock.

    All that said, it's a good conversation piece, and probably worth the price for that.

    • by Roblimo ( 357 )

      What Bruce said. Not everything needs to have a practical application to be interesting. Some things are just fun.

      That thing (made out of metal) would make one heck of a 'granny gear' for my recumbent trike, though.

  • by Solandri ( 704621 ) on Tuesday July 07, 2015 @01:34AM (#50060435)
    And you get Machine with Concrete [] by Arthur Ganson.
    • You know, I can't help but wonder, if you stuck a really, really high RPM drive on his machine whether you'd bust the concrete at the final stage or blow up the first gearbox stage first?

      Or, assuming you put the fastest drive on the first stage that wouldn't blow it up, whether the concrete would weather away before being broken off?

  • In order to find practical applications, I think it's important to quantify what it you've got through measurements, mainly by breaking them. You want to know what kind of torque the later stages of that 11million+ ratio gearset can actually withstand. I'd probably try hooking a dremel on the "fast" end and some kind of lever pressing on an obstacle or a digital scale on the "slow" end. I suspect that some stages would be prone to failure much sooner than others. Different materials and more precise constru
    • I'd have fun clamping the opposite end, then counting to see how many revolutions it would take before it skipped or tore itself to pieces.

  • Tried to build this with my 3d printer. Something broke, and something seized, and to my amazement, it turned out to have 1:infinity gear reduction.

    • Yeah, I'm not so sure it would be all that possible to create on a desktop 3D printer. I don't know if part quality would be good enough. The creator here used Shapeways who uses an laser based 3D printer.
  • by Anonymous Coward

    The tip of a wind turbine typically moves with 75m/s. The generator turns with 1500rpm. For all sizes of blades.

    At 50m blades (100m diameter) that means the roter turns 7.5rpm. The gearing ratio needed is 1:200 - transporting 3MW continuous energy.

  • by Anonymous Coward

    This video: Grinder Gears [] shows the key to the gearing ratio. The 'one rotation = skipping just one tooth' is demonstrated here, and it's also shown that the gear is not reversible. You can't reverse the process by turning the output gear and have it spin the input gear, it simply won't budge because it's not a direct gearing. The inner "yellow" gear rocks around a bit like turning a straw in a small soda pop bottle opening. That is: The smaller opening provides a restriction and the longer ends of the

  • It reminds me of the harmonic drive [] - a low backlash, high ratio compact gear.

    Other comments have noted that a very high ratio would need very strong matariels to transfer significant power.
    That's true, but sometimes the point isn't power, the point is to move things over very small distances precisely.

  • Even on a power drill, you're not going to move anything very far. So you need to hook it up to something where there's not much power and lots of turns on the input.

    Screw it, I'm hooking mine up to the hamster's wheel.

  • What sort of devices is this invention geared towards?

  • I can see an instant application for this, obviously using a lower ratio: hand winches.

    Same principle as a block and tackle. For every turn of the crank, you can reduce the ratio to something like 1 in 100 and lift (theoretically) 100 times the crank load 1/100 the outer circumference of the spool. For a motor-driven winch, you could use a low voltage, low torque, high speed motor (like you'd get in a Dremel), spin that at 10,000rpm, reduce it in one of these blocks by 1/1,000 and end up with (again, theore

    • Only if you're very weak. The gearing mechanism probably wouldn't be able to cope wit anything an average human couldn't lift. It's plastic!
      • by Roblimo ( 357 )

        So laser-print it with metal. Might not be ultra-strong, but way better than plastic. - []

  • Both the design and potential torque are astonishing.

    Thanks /.

  • I see someone discovered the planetary gear system.

    I love it when kiddies discover what has been around even before steam.

  • That's the point of something like this... Assuming the gears could take the weight. You'd want to build the gears out of metal obviously because towards the end they'd need serious torque. But lets say you have a very low power situation... maybe a little wind mill or a small solar powered electric motor... then you need to do something that moves something huge but you don't really care if it takes a month. You set this up... walk away... come back in a month... boom.

    • by Anonymous Coward

      I'm guessing the boom is when the 3d printed gears explode under the pressure they've been exposed too?

  • This is just another example of why 3D printing isn't "There" yet...
    The concept is cool, but the material it's made out of isn't strong enough to make this a high torque device. That leaves precision, but 3D printing isn't nearly precise enough either... by the time this has made enough turns to make the output even do one revolution, the sketchiness of the printers output makes even the idea of labeling it 3,000,000/1 kind of a joke.

    Maybe you could use the parts as cast forms to make metal parts out of? Bu

    • by PPH ( 736903 )

      But even then, why not just mill it?

      Proof of concept/prototyping. Go out and get an estimate to have this gizmo milled.

      Yeah, its pretty useless. But it's just a technology demonstration.

  • My God, when will this ever end? It's like trying to find the end of Pi, or the guy who spends his time adding "1" to the total.
  • How can I get this car out of second gear []?

"If you lived today as if it were your last, you'd buy up a box of rockets and fire them all off, wouldn't you?" -- Garrison Keillor