The issue you noticed on the end is related to a tiny flaw on the design, you should use tapered roller bearings on the ends! There is force being applied axially as well as radially, thus it requires tapered roller bearings instead of just standard radial ball bearings.
Didnt know tapered roller bearings were for multi directional loads, explains why you see them in automotive drivetrain applications. Good to know thanks for the info
@@jasonwhite2028 yes but they have a large nut or snap ring to hold it in place, so it's not the bearing on its own, and it's only in certain cars, possibly just trucks, I believe. The hubs of most cars are just a large straight bearing that gets pressed into the knuckle. While trucks and anything larger has tapered bearings that are made to come apart so you can pack grease into it and then pop it back together and fasten it down
I hear mention of tapered roller bearings mentioned around machinist lathes. Depending on what angle you’re cutting the load could be axial, radial or a mix of both.
I don't know if it's useful, but it is hardly unnecessary. It may lead to a more advanced design. Try it with beveled helical gears and increase the gear contact by increasing the length of the gear teeth. You have a rather large gap between the teeth and shaft. More contact may increase stability.
I don't quite understand what you mean. Can you make a model in your workshop to illustrate the principle, and then upload a video showing how it works?
If you want it to operate smoothly, three things are to take into account : 1) the distance of each nutation gear to the nutation point depends on several factors such as tha nutation ratio and the difference in tooth count in each gear mesh, if not followed, the gears don't mesh perfectly 2) 3d printed gears need to be work smoothed by runing them with an abrasive to eliminate surface artifacts 3) greasing the gears is key in smooth and qiet operation. Back to the first point, all herringbone gears have an average contact point wich describes a circle, the center of the fear being the center of this circle. With a nutation angle α, and an offset of a nutation gear from the nutation point (where the oblique and straigt axes cross) δ, and a meshing gear of radius r1 the nutation gear average radius needs to be r1/cos(α) + δ*tan(α), if you trace the simple meshing on a piece of paper to find the proper dimensions, you will find this formula with simple trigonometry. On a side note, having the same nutation gears and meshing gears will simplify the design as the nutation gears will bea simetrical to the nutation point
So it’s possible to avoid the pulsing entirely if you design the gears to meet the constraints you described? I wonder if it would be zero-backlash like harmonic drives?
The tilted gear introduces a mass imbalance that wobbles the shaft. The mass needs to be balanced, like balancing the crankshaft and bottom-end assembly in a piston engine. Maybe the sides of the nutating gear that are tilted outward could be hollowed out to remove the mass asymmetry?.
Why do you say this doesn't involve deformation? The end plates appear to deform (this is most visible in the thumbnail design - the orange plates are clearly shifting, especially the output side). I'd be interested in a proper 3d model showing zero deformation necessary while maintaining constant output ratio & continual output torque - it's not obvious to me that such a design exists given the changing angle of the teeth.
@@wedmunds The outer plates cannot tilt relative to the center tube without deformation. And yet they clearly are tilting relative to the center tube. This implies deformation. You are correct in that the center tube could be deforming instead of the end plates; either way this involves deformation (my point).
If the materials choices were better deformation would be reduced or eliminated. Poor materials will cause deformation in any mechanical system, yet you seem to think it is a specific flaw to this drive? He even states in the video that as the materials are not solid it is deforming I suspect you only have the most surface level understanding of mechanisms. AND skipped most of the video.
@@backtoearth1983 Kindly stop with the unwarranted assumptions. The point of contact of the center cylinder with the outer plates shifts both axially and radially as the assembly rotates. And the gear extends a finite amount radially. It's easier to envision the problem if instead of treating the contact as two crown gears interacting, you unfold it 90 degrees and envision it as two spur gears interacting, where one spur gear has both a non-central axis _and_ said axle isn't square with the gear. This results in the contact point shifting both radially and axially. It shifting radially isn't the end of the world - non-circular gears do exist - however, it also shifting axially introduces an additional set of constraints between different planes of the gear. (Normally with a gear of finite width different planes of the gear are mostly independently constrained - see e.g. helical versus herringbone gears: you can effectively independently rotate each plane of the gear and still result in a valid (though potentially hilariously impractical) gear.) Non-circular gears are normally already fairly constrained. It is _not_ obvious to me that there exists a solution to the further constrained system, although I'd love to be proven wrong.
the fact that so many teeth engage at once makes it far more suitable for high torque 3D printed gears as demonstrated here!! typical configurations will result in the teeth breaking if they're a weaker material
Nice design. A few thoughts here: - Center shaft experiences bending load equal to 2x of gear teeth load (equals to 2 * output torque / gear radius). It's better to make it as stiff as possible - Unbalanced moment caused by big gear's nutation can be completely balanced out by two counterweights attached to the central shaft. If made from metal they should fit right between red and yellow gears.
The most useful aspect about it is making interesting UA-cam content like your video. Which I appreciate seeing stuff like this. Overall though it’s noisy, vibrates (even when compensated for), inefficient due to friction and overly complex thus expensive. Its the answer to a question no one ask. However like mentioned I really enjoy seeing stuff like this. Just because it’s impractical doesn’t mean it isn’t fun.
It’s easy to see that for a continuous input you have a pulsing outout. Even In the double gearbox configuration. You can improve the smoothness of the output by offsetting the mirrored gearbox by 90 degree rotation.
I am not sure how to explain it, referencing 8:32 But if you install the right side transmission to be 90 deg out of phase with the left side, that will it switch which side does the pushing. Essentially you can smoothen the output motion by making it so that the push (instead of being in sync) happens twice per rotation instead, right left right left…
@@marco_gallone I'm not sure if you are referring to the smoothness of the axial movements. But if you picture the circular motion, your suggested offset of 90 degrees or pi/2 is equivalent to the sum of a sine and a cosine, which results in a larger amplitude, which means more axial vibration in both directions. Mathematically, as you know, only a phase shift of 180 degrees or pi will cancel. Here are two examples in Desmos: 'qfcs5camdc' (180 degrees) and 'kkvv0zanus' (90 degrees).
Very interesting and bizarre stuff, I think the biggest shortcoming it has, is that the output is basically getting 'twitched' between gear meshes as a means of moving. So your output side isn't able to deliver a consistent level of torque in a direction. Also I think this means that despite the 40:1 ratio or so, the mechanical advantage is actually lower, each time it steps back it is undoing the mechanical advantage, then the forward stroke has to put it back that much further, so that's a sort of continuous movement ineffeciency. So it's mechanical advantage factor would be measured in the forward-wobble and advancement region only, if that makes sense. Basically it will act like a 40:1, but the input torque used to move it, will take the effort of something more like a 30:1.
This was my initial impression but actually I don't think this is a fundamental problem of the mechanism, but the tolerances/manufacturing of the part. Like, its not like contact is made to force the gear once per per rotation, the contact is made cyclically around every contacting gear tooth in rapid succession. I think that there are also ways to optimize the tooth design. Before involute gear tooth, the same (or similar) criticism could be made for simple gears!
I was thinking the same thing with the engage and disengage being horribly indirect compared to planetary or worm etc, but it also looks like it could be constantly engaged with just a portion of the gear as it wobbles rotating the contact position? Not sure but the vibration alone makes this seem pretty unviable, still cool to learn about
Maybe. But the real show-stopper is friction. Properly designed gear trains have friction only in the bearings but never on the teeth (rolling motion via evolute geometry). Here, there teeth are sliding into position. Big no-no in engineering and the reason why worm gears wear out so quickly.
Excellent work! I hope that students pursuing advanced degrees in mechanical engineering will consider focussing on this concept for their research thesis.
This is very cool! It seems that the imbalance of the inner (yellow) gear could be solved by inserting a mass strategically, like balance weights on a car wheel.
I would love to see a really high load on this gearbox. Maybe test its limits with what 3D printing material and precision you have, until a gearbox of a certain size fails. I bet if you optimize it as much as you can, it may be capable of producing much more torque for its size and mass than other more commonly used gearboxes.
@@renedekker9806 because of the amount of surface area in contact between the gears, the load distribution on them is completely different than other gearboxes. That means that the gears can handle many times the force before failure. This thing is only made of plastic, imagine one made of metal. Optimizing this box would be a really fun project for me, if I had the means to do it
@@christiangray7826 _"because of the amount of surface area in contact between the gears"_ - the real contact is still only 1 or 2 gear teeth, the force concentrates on those teeth. Because the gear teeth have an angle, that force also tries the gear teeth to disengage. In a normal gear box, that force is towards the centre of the gear, which is easily withstood by the gear. In this gearbox, that force is perpendicular to the gear itself, causing the gear and its axle to bend. I would not put large loads on it.
@@renedekker9806 We disagree on its function, but doesn’t that make it even more interesting to see it tested to failure? Whether it performs well or not, it would be very fun to learn more about. Maybe it has no potential. Maybe it has plenty. Only one way to find out, and that’s optimizing it
You can make the gearing ratio even slower if you have 1 tooth difference between the two yellow gears, and each orange gear having 1 tooth more than its yellow mate.
I’m very impressed by the finish on that clear cover! I used to work with acrylics and polycarbonate many years ago. That looks as good as an injection moulding. The gearbox is an impressive force multiplier! 👍🏻
as you mentioned, a solid casing made of thick steel plate, machined solid steel parts, some grease and this thing would genuinely be useful in a lot of industrial applications
@@Mike-jm5wttried tik tok once, it's still 100 times worse, not even joking. Tho youtube is getting worse and worse and content farms are also responsible for that
@@FadkinsDiet You'd have to ask the channel operator, but it's possible. According to several channels that have investigated, they took affiliate money from everyone they could, sponsored or not.
Don't know why you think that nobody talks about this, because this is well known solution for high gear rations. Nevertheless that's good you brought it out
It is possible to compensate any dynamic unbalance by adding counter weights to your swashplate. Increase the radii of your swashplate and bearing to create space for it. The increase will also provide for better stiffnes.
The Friction and Deformation Forces here are insane. Not only are you engaging and disengaging parabolic teeth at really weird angles, but you are also constantly forcing elastic deformation on all parts, making it incredibly inefficient compared to similar reduction arrangements. Main benefit is low amount of parts, I guess? but even then, your wear is gonna be much higher, due to the applied forces being extremely varying.
I had a winch that used a planetary drive but it was unusual, It had the motor connected to the planet gears and no sun gear. It drove between 2 ring gears which had a different number of teeth. One was mounted to the housing the other to the drum.
Very interesting. BTW I watch youtube on a Humax box and it is not easy to flag a LIKE if the video ends immediately. 10 or so seconds of warning at the end would give me time to hit pause and LIKE.
I think even though it looks like there's a lot of teeth engaging it's still only one at a time. The teeth in front of and behind the one in contact are about to touch but aren't touching yet.
Great work. If you use a much finer gear pitch, the distance of nutation can be reduced greatly, reducing imbalance forces. If you casually look at a harmonic drive, the gear pitch more closely resembles a straight knurl rather than gear teeth.
Maybe good for solar panel tracking because of the slow movement required. Could probably have the gearbox sealed and filled with oil for low maintenance since solar arrays are pretty remote sometimes
Idk about the torque situation - I'd say it's only actually engaging on or two teeth at a time, a lot of other teeth are really close, especially the closer they are to the contact point but unless the gears are flexing, no additional teeth are actually making proper contact. I'd think a next step could be to compare and contrast the design to a planetary configuration to see if there are any benefits but it's definitely interesting either way.
Usefull in the circumstances you don't have access to flexible material for an harmonic drive. Harmonic drive don't have the wobbling of middle gear, much greater ratio and tooth engagement.
in praxis you can make the wobblator and its shaft out of 1 part, id opt for a much larger shaft thoug, id go so far to increase its diameter to the point where its just a bit smaller than the inner diameter of the ring. stator
I'm sure the angle for the shaft needs to be big enough for the gear teeth to pass by each other as it spins, but reducing this angle as much as possible will reduce the vibrations as well.
Since the input and output are co-axial I think you could make a cool clock design with this, with a 1rpm input that gives you your minute hand with the input shaft going all the way through to the front and then with a design with a 1:60 reduction then the output wraps around the minute hand and gives you the hour hand and the low speed means that the noise and balance is not so much of an issue
Just a different form of what I know as a harmonic drive, only a lot worse performance. Harmonic drives have high gear reduction, they're relatively compact, have close t0 0 backlash, run smooth/quiet, and are robust. They are commonly used on CNC machine centers to drive automatic tool changers. We have a bunch of Toyoda's that use them, a few machines are over 30 years old, never had to touch the harmonic drive sections.
Fascinating. I think that, with a different way of meshing the teeth, the engagement could be gentler, like helical gears, though the vibration will remain an issue.
I like this. Still not sure about it vs worm drive but either way I will take the extra arrow for my quiver. The one thing I can say is worm drive vs this has a perpendicular input naturally so this might have some advantage for situations.
Steel gears with tapered bearings, immersed in a gearbox full of heavy oil would probably solve most of your issues. No more flex, significantly less noise/vibration/wear.
Interesting idea, my only concern would be high vibration, possibly having the gearbox on a floating platform and a lovejoy style coupling to absorb vibration going to the motor. The torque output has to be insane though
instead of other gear to oposite the angular momentum, why dont you use a metal ring attatched with the first yellow gear but with the oposite angle for balance the wheght, adjusting its centr of mass to reduce vibration
I'm sure there's an application somewhere that's useful vs a worm drive. Maybe if you needed a large ratio like a two stage worm drive might be less desirable than this nutating layout esp considering the lower stress on teeth. Also mechanisms that might depend on specific gear ratios for timing, since your 1:409 ratio is super compact for that kind of specific extreme ratio
With just a pair of metal worm/gears in series like the ones you showed at the start, you'd get 1600:1. Metal, simpler, stronger, quieter, cheaper, so, ...! Great to explore this kind of stuff, though!
Its a matter of use cases. Most of the time you don't need a planetary gear, but when you do its very useful to have. Same thing here, a worm drive is fine if you have the space. But if you are limited in space a design like this is nice to have.
Certainly a nice gadget but not a solution for real-life problems: the show-stopper is friction. *Properly designed gear trains have friction only in the bearings but never on the teeth* (rolling motion via evolute geometry). Here, there teeth are sliding into position. Big no-no in engineering and the reason why worm gears wear out so quickly.
That's wrong. Checkout the harmonic drive or the cycloidal drive. They are zero backlash drives and require friction on the gears. Here's a good explanation of the harmonic drive: ua-cam.com/video/7QidXf9pFYo/v-deo.html
That's not true. Involute gears have sliding and rolling contact. Pure rolling only happens at the pitch radius. Some sliding is a benefit in operation as it keeps the oil film from collapsing.
@@zachary3777 Haha! Correct! Totally accept your response in the context of substantial forces & hardened steel surfaces. However, in the concept shown in the video, we are seeing a "dry" system built from a low-melting-point material. Here, we should aim at a system where we only see rolling motion & big radii if we want the system to survive for a reasonable time... self-lubricating materials would be a bonus too...
That is interesting. In a sense , it looks like a mechanical relative of the planetary gear, or even the differential, If the output is the center and you hold one shaft while spinning the other. Perhaps counterweights in the nutating gear would cure the problem of being out of balance.
It’s an interesting concept. Have you done a comparison with a traditional gear with the same ratio for friction? I have a feeling the friction may be too high for practical purposes. Adding bearings to the shaft to reduce the friction there was a great idea, but as you mentioned in the video, there are multiple teeth meshing simultaneously instead of just one and that means more friction.
Some perhaps interesting ideas, a different tooth profile, like herringbone might be more forgiving and yield a more silent operation at a higher speed. Alternatively, could you not just make the sides flat and simply surface the sides with a "sticky" material like an o-ring or silicon coating/layer? Are the gears even needed for it to nutate if there is sufficient compliance and friction in the surfaces?
I spent a bit of time working on it but I could not justify the cost of adequate tapered bearings for my experiment. They seem to work best when the input speed is relatively low but provide great torque in a fairly compact package, printing them is a problem because all the tolerances compound and you get a lot of vibration out of it.
Try swapping the incoming and outgoing rotation. In order not to slow down the final rotation, but rather to accelerate it. Is it possible to create a propeller based on this transmission mechanism ? For example, for "pedal catamarans".
just a tought , dunno if this would work at all, but instead of adding a second gearbox if you make the two outer gears each half the weigth of the diddle gear , and then give them an oposite inclination to the middle on so when the midlle one force is maximum at one point the two other max out in the other direction ?, would put more strain on the shaft but i think its doable
Would it be possible to play with the weight distribution of the wobbling gear to make it stable? I guess that might be more dependent on manufacturing quality compared to adding a mirrored gear, but at least it would only be one unit
The main advantage of a pericyclic gearbox is vey high output torque because several gear teeth are in contact at the same time. Because of its inherent design, we have this vibration problem causing the gearbox to self destruct. The only way to cancel out the vibration is by adding a "mirror image" of the gearbox. But then the output is now in the center of the whole gearbox which leaves us no other option but to use a spur or helical gear which is quite counterintuitive.
I could really see this in some super low speed application that needs only torque. So you could stick a smaller motor on it and call it good. That 400-1 is crazy! and could be useful, just needs some optimization
Yes, but this design is much more 3D printer friendly. James Bruton did some experiments with a printable hamonic/strain wave drive but ultimately settled on cycloidal drives for his projects because of issues he had. ua-cam.com/video/QoBgSWkJyM4/v-deo.html Maybe someone will see a solution to the balance issue other than using a second gearbox and a better system of bearing (or maybe even something like a delrin bushing) might further improve things.
I've seen high torque gearboxes before, and now I've seen a high twerk gearbox.
Work it baby, work, work, work.
that was my nickname in highschool
That joke really *grinds* my *gears*…
out
The issue you noticed on the end is related to a tiny flaw on the design, you should use tapered roller bearings on the ends! There is force being applied axially as well as radially, thus it requires tapered roller bearings instead of just standard radial ball bearings.
Might as well make the gear teeth like the cycloidal gears as well.
Didnt know tapered roller bearings were for multi directional loads, explains why you see them in automotive drivetrain applications. Good to know thanks for the info
Slab bearings. Barrel shaped like old right axles on Mercedes swing axle
@@jasonwhite2028 yes but they have a large nut or snap ring to hold it in place, so it's not the bearing on its own, and it's only in certain cars, possibly just trucks, I believe. The hubs of most cars are just a large straight bearing that gets pressed into the knuckle. While trucks and anything larger has tapered bearings that are made to come apart so you can pack grease into it and then pop it back together and fasten it down
I hear mention of tapered roller bearings mentioned around machinist lathes. Depending on what angle you’re cutting the load could be axial, radial or a mix of both.
I don't know if it's useful, but it is hardly unnecessary. It may lead to a more advanced design. Try it with beveled helical gears and increase the gear contact by increasing the length of the gear teeth. You have a rather large gap between the teeth and shaft. More contact may increase stability.
Recreate this with magnets. No friction.
I don't quite understand what you mean. Can you make a model in your workshop to illustrate the principle, and then upload a video showing how it works?
@@ParaBellum2024 That's a weird way to troll. 🤔🤨
@@mspeir i just looked at your channel bc i was interested if you had a workshop due to parabellums comment , you earned a new sub.
@@sayorancode I haven't posted in years, but thank you.
If you want it to operate smoothly, three things are to take into account :
1) the distance of each nutation gear to the nutation point depends on several factors such as tha nutation ratio and the difference in tooth count in each gear mesh, if not followed, the gears don't mesh perfectly
2) 3d printed gears need to be work smoothed by runing them with an abrasive to eliminate surface artifacts
3) greasing the gears is key in smooth and qiet operation.
Back to the first point, all herringbone gears have an average contact point wich describes a circle, the center of the fear being the center of this circle. With a nutation angle α, and an offset of a nutation gear from the nutation point (where the oblique and straigt axes cross) δ, and a meshing gear of radius r1 the nutation gear average radius needs to be r1/cos(α) + δ*tan(α),
if you trace the simple meshing on a piece of paper to find the proper dimensions, you will find this formula with simple trigonometry. On a side note, having the same nutation gears and meshing gears will simplify the design as the nutation gears will bea simetrical to the nutation point
So it’s possible to avoid the pulsing entirely if you design the gears to meet the constraints you described? I wonder if it would be zero-backlash like harmonic drives?
The tilted gear introduces a mass imbalance that wobbles the shaft. The mass needs to be balanced, like balancing the crankshaft and bottom-end assembly in a piston engine. Maybe the sides of the nutating gear that are tilted outward could be hollowed out to remove the mass asymmetry?.
Neat fact related to your use of 4 degrees, that's also the same degree that water will travel uphill against gravity due to capillary action.
i think this was genuinly one of the least annoying sponsor presentation ive seen,nice job bro
Looks like a neat variant of the harmonic drive that doesn't involve deformation
Why do you say this doesn't involve deformation? The end plates appear to deform (this is most visible in the thumbnail design - the orange plates are clearly shifting, especially the output side).
I'd be interested in a proper 3d model showing zero deformation necessary while maintaining constant output ratio & continual output torque - it's not obvious to me that such a design exists given the changing angle of the teeth.
@@TheLoneWolfling the plates are tilting not bending. If anything, the center tube is the one that should be deforming
@@wedmunds The outer plates cannot tilt relative to the center tube without deformation. And yet they clearly are tilting relative to the center tube. This implies deformation.
You are correct in that the center tube could be deforming instead of the end plates; either way this involves deformation (my point).
If the materials choices were better deformation would be reduced or eliminated.
Poor materials will cause deformation in any mechanical system, yet you seem to think it is a specific flaw to this drive? He even states in the video that as the materials are not solid it is deforming
I suspect you only have the most surface level understanding of mechanisms. AND skipped most of the video.
@@backtoearth1983 Kindly stop with the unwarranted assumptions.
The point of contact of the center cylinder with the outer plates shifts both axially and radially as the assembly rotates. And the gear extends a finite amount radially.
It's easier to envision the problem if instead of treating the contact as two crown gears interacting, you unfold it 90 degrees and envision it as two spur gears interacting, where one spur gear has both a non-central axis _and_ said axle isn't square with the gear.
This results in the contact point shifting both radially and axially. It shifting radially isn't the end of the world - non-circular gears do exist - however, it also shifting axially introduces an additional set of constraints between different planes of the gear. (Normally with a gear of finite width different planes of the gear are mostly independently constrained - see e.g. helical versus herringbone gears: you can effectively independently rotate each plane of the gear and still result in a valid (though potentially hilariously impractical) gear.)
Non-circular gears are normally already fairly constrained. It is _not_ obvious to me that there exists a solution to the further constrained system, although I'd love to be proven wrong.
the fact that so many teeth engage at once makes it far more suitable for high torque 3D printed gears as demonstrated here!! typical configurations will result in the teeth breaking if they're a weaker material
Nice design. A few thoughts here:
- Center shaft experiences bending load equal to 2x of gear teeth load (equals to 2 * output torque / gear radius). It's better to make it as stiff as possible
- Unbalanced moment caused by big gear's nutation can be completely balanced out by two counterweights attached to the central shaft. If made from metal they should fit right between red and yellow gears.
The most useful aspect about it is making interesting UA-cam content like your video. Which I appreciate seeing stuff like this.
Overall though it’s noisy, vibrates (even when compensated for), inefficient due to friction and overly complex thus expensive. Its the answer to a question no one ask.
However like mentioned I really enjoy seeing stuff like this. Just because it’s impractical doesn’t mean it isn’t fun.
It’s easy to see that for a continuous input you have a pulsing outout. Even In the double gearbox configuration. You can improve the smoothness of the output by offsetting the mirrored gearbox by 90 degree rotation.
I'm struggling to understand what you mean. Can you make this design in your workshop, and then upload a video showing how it works?
I am not sure how to explain it, referencing 8:32
But if you install the right side transmission to be 90 deg out of phase with the left side, that will it switch which side does the pushing. Essentially you can smoothen the output motion by making it so that the push (instead of being in sync) happens twice per rotation instead, right left right left…
@@ParaBellum2024 bot
@@sayorancode Wot?
@@marco_gallone I'm not sure if you are referring to the smoothness of the axial movements. But if you picture the circular motion, your suggested offset of 90 degrees or pi/2 is equivalent to the sum of a sine and a cosine, which results in a larger amplitude, which means more axial vibration in both directions. Mathematically, as you know, only a phase shift of 180 degrees or pi will cancel. Here are two examples in Desmos: 'qfcs5camdc' (180 degrees) and 'kkvv0zanus' (90 degrees).
Very interesting and bizarre stuff, I think the biggest shortcoming it has, is that the output is basically getting 'twitched' between gear meshes as a means of moving. So your output side isn't able to deliver a consistent level of torque in a direction. Also I think this means that despite the 40:1 ratio or so, the mechanical advantage is actually lower, each time it steps back it is undoing the mechanical advantage, then the forward stroke has to put it back that much further, so that's a sort of continuous movement ineffeciency. So it's mechanical advantage factor would be measured in the forward-wobble and advancement region only, if that makes sense. Basically it will act like a 40:1, but the input torque used to move it, will take the effort of something more like a 30:1.
It's very much like on a worm gear reduction, friction takes away quite a bit of the performance.
This was my initial impression but actually I don't think this is a fundamental problem of the mechanism, but the tolerances/manufacturing of the part.
Like, its not like contact is made to force the gear once per per rotation, the contact is made cyclically around every contacting gear tooth in rapid succession.
I think that there are also ways to optimize the tooth design. Before involute gear tooth, the same (or similar) criticism could be made for simple gears!
@@MatrixRay19I am unsure of this. I think at first glance you'd assume something similar of cycloidal gearboxes
I was thinking the same thing with the engage and disengage being horribly indirect compared to planetary or worm etc, but it also looks like it could be constantly engaged with just a portion of the gear as it wobbles rotating the contact position? Not sure but the vibration alone makes this seem pretty unviable, still cool to learn about
Maybe. But the real show-stopper is friction. Properly designed gear trains have friction only in the bearings but never on the teeth (rolling motion via evolute geometry). Here, there teeth are sliding into position. Big no-no in engineering and the reason why worm gears wear out so quickly.
Excellent work! I hope that students pursuing advanced degrees in mechanical engineering will consider focussing on this concept for their research thesis.
This is very cool! It seems that the imbalance of the inner (yellow) gear could be solved by inserting a mass strategically, like balance weights on a car wheel.
I would love to see a really high load on this gearbox. Maybe test its limits with what 3D printing material and precision you have, until a gearbox of a certain size fails. I bet if you optimize it as much as you can, it may be capable of producing much more torque for its size and mass than other more commonly used gearboxes.
It is not suited for high load. With a 45 degree tooth angle, the output force is equal to the bending force on the inner gear.
@@renedekker9806 because of the amount of surface area in contact between the gears, the load distribution on them is completely different than other gearboxes. That means that the gears can handle many times the force before failure. This thing is only made of plastic, imagine one made of metal. Optimizing this box would be a really fun project for me, if I had the means to do it
@@christiangray7826 _"because of the amount of surface area in contact between the gears"_ - the real contact is still only 1 or 2 gear teeth, the force concentrates on those teeth. Because the gear teeth have an angle, that force also tries the gear teeth to disengage. In a normal gear box, that force is towards the centre of the gear, which is easily withstood by the gear. In this gearbox, that force is perpendicular to the gear itself, causing the gear and its axle to bend.
I would not put large loads on it.
@@renedekker9806 We disagree on its function, but doesn’t that make it even more interesting to see it tested to failure? Whether it performs well or not, it would be very fun to learn more about. Maybe it has no potential. Maybe it has plenty. Only one way to find out, and that’s optimizing it
You can make the gearing ratio even slower if you have 1 tooth difference between the two yellow gears, and each orange gear having 1 tooth more than its yellow mate.
Exactly, the ratio increases as the number of teeth get closer together.
6:12 FWIW, the teeth on *BOTH* sides of the center gear are engaged, so the total force is _really_ spread out.
I’m very impressed by the finish on that clear cover! I used to work with acrylics and polycarbonate many years ago. That looks as good as an injection moulding. The gearbox is an impressive force multiplier! 👍🏻
as you mentioned, a solid casing made of thick steel plate, machined solid steel parts, some grease and this thing would genuinely be useful in a lot of industrial applications
my thoughts exactly. could you imagine them being used with a diesel engine? the torque output would be insane.
They are very interesting and you have great physics and cad skills
Neat. It's a shame that UA-cam is working hard to commit hara-kiri because I'm really going to miss channels like this one.
@@Mike-jm5wttried tik tok once, it's still 100 times worse, not even joking. Tho youtube is getting worse and worse and content farms are also responsible for that
Hopefully they move to one of the pop up competitors like odysee or something
Were the affiliate commissions for the jlc3dp stolen by honey?
@@FadkinsDiet You'd have to ask the channel operator, but it's possible. According to several channels that have investigated, they took affiliate money from everyone they could, sponsored or not.
You have amazing skills in explaining things clearly. Well done.
Don't know why you think that nobody talks about this, because this is well known solution for high gear rations. Nevertheless that's good you brought it out
Looks useful for high torque applications, such as driving a winch and spool.
It is possible to compensate any dynamic unbalance by adding counter weights to your swashplate. Increase the radii of your swashplate and bearing to create space for it. The increase will also provide for better stiffnes.
The Friction and Deformation Forces here are insane. Not only are you engaging and disengaging parabolic teeth at really weird angles, but you are also constantly forcing elastic deformation on all parts, making it incredibly inefficient compared to similar reduction arrangements. Main benefit is low amount of parts, I guess? but even then, your wear is gonna be much higher, due to the applied forces being extremely varying.
yes 👍🏼 you're correct
that's why this gear formation alway's goes under " reverse gear "
Sort of like a harmonic drive that doesn't require the fragile circular spline element. Cool!
@7:05 the screws start to loosen. And that, ladies and gentlemen, is how Harley Davidsons are made.
I had a winch that used a planetary drive but it was unusual, It had the motor connected to the planet gears and no sun gear. It drove between 2 ring gears which had a different number of teeth. One was mounted to the housing the other to the drum.
Very interesting. BTW I watch youtube on a Humax box and it is not easy to flag a LIKE if the video ends immediately. 10 or so seconds of warning at the end would give me time to hit pause and LIKE.
A former Czech friend many years ago came up with a compact compound planetary gearbox that was actually capable of infinity to zero gear ratios.
I think even though it looks like there's a lot of teeth engaging it's still only one at a time. The teeth in front of and behind the one in contact are about to touch but aren't touching yet.
cool idea. maybe the center gear could be balanced by modulating the infill percentage at least a bit.
This broke my mind a bit but it is awesome
you could make it half the size and 3d print it in metal to get strength and precision . great work!
Great work. If you use a much finer gear pitch, the distance of nutation can be reduced greatly, reducing imbalance forces.
If you casually look at a harmonic drive, the gear pitch more closely resembles a straight knurl rather than gear teeth.
Maybe good for solar panel tracking because of the slow movement required. Could probably have the gearbox sealed and filled with oil for low maintenance since solar arrays are pretty remote sometimes
Idk about the torque situation - I'd say it's only actually engaging on or two teeth at a time, a lot of other teeth are really close, especially the closer they are to the contact point but unless the gears are flexing, no additional teeth are actually making proper contact. I'd think a next step could be to compare and contrast the design to a planetary configuration to see if there are any benefits but it's definitely interesting either way.
Thank you for sharing your knowledge on the gearing
Usefull in the circumstances you don't have access to flexible material for an harmonic drive. Harmonic drive don't have the wobbling of middle gear, much greater ratio and tooth engagement.
in praxis you can make the wobblator and its shaft out of 1 part, id opt for a much larger shaft thoug, id go so far to increase its diameter to the point where its just a bit smaller than the inner diameter of the ring. stator
I'm sure the angle for the shaft needs to be big enough for the gear teeth to pass by each other as it spins, but reducing this angle as much as possible will reduce the vibrations as well.
Since the input and output are co-axial I think you could make a cool clock design with this, with a 1rpm input that gives you your minute hand with the input shaft going all the way through to the front and then with a design with a 1:60 reduction then the output wraps around the minute hand and gives you the hour hand and the low speed means that the noise and balance is not so much of an issue
In practical sense, all tork is on one/ two teeth , balance can be mitigated, nice work thanks for knowledge
Interesting variation of the harmonic drive. 👍👍
Just a different form of what I know as a harmonic drive, only a lot worse performance. Harmonic drives have high gear reduction, they're relatively compact, have close t0 0 backlash, run smooth/quiet, and are robust. They are commonly used on CNC machine centers to drive automatic tool changers. We have a bunch of Toyoda's that use them, a few machines are over 30 years old, never had to touch the harmonic drive sections.
Thanks I will look those up
Fascinating. I think that, with a different way of meshing the teeth, the engagement could be gentler, like helical gears, though the vibration will remain an issue.
this would've been a great example for my machine design course
I like this. Still not sure about it vs worm drive but either way I will take the extra arrow for my quiver. The one thing I can say is worm drive vs this has a perpendicular input naturally so this might have some advantage for situations.
There should be a counter balance weight installed to keep the center of mass around the center of rotation.
I think there may be less friction losses in comparison to worm gears. I think it might be used to aim anti missile batteries. Real slick!
Excellent job on making this video and explanation. Thank you for sharing with us.
3D printing is showing us so many new systems.
Sürekli kendini geliştiriyorsun dostum tebrik eder başarılı işler dilerim.
Could be great in a clock escapement.
Very inspiring! Ever considered to make a calender clock this way?
Yes 🙏🏼 It could come of a side way 30 to 31 and every fifths year, you get to minus one reset a day for April's fool
I have an idea for a clutch mechanism, that would require a lot of pressure but not a lot of parts.
Steel gears with tapered bearings, immersed in a gearbox full of heavy oil would probably solve most of your issues. No more flex, significantly less noise/vibration/wear.
Keep in mind, mirroring the gear boxes doubles the gear contact area. 2x the strength, or same strength, half the weight neaded in materials
Might have a use in gear reduction socket drivers unless planet gears are still better.
This is exactly how an e-park brake can work with only a tiny 12V brushed DC motor. At least all VW group cars have this design.
e-park brake? 😂 Thats a new one. I always say parking brake because thats the purpose of it, designed to save your pawl when parking.
Interesting idea, my only concern would be high vibration, possibly having the gearbox on a floating platform and a lovejoy style coupling to absorb vibration going to the motor. The torque output has to be insane though
Superb! I wonder how well this would work in low speed conditions like bicycle gearing? I’m looking forward to see more. Thanks
These would be great to have in the hubs of each wheel on a vehicle with the proper gear ratio
Now we need a competition with 3D Printing Academy
LoL 👍🏼 3D principal printing's are like climbing up the Qualities of a predrodic table's
seems like a good application for differential gear
instead of other gear to oposite the angular momentum, why dont you use a metal ring attatched with the first yellow gear but with the oposite angle for balance the wheght, adjusting its centr of mass to reduce vibration
I'm sure there's an application somewhere that's useful vs a worm drive. Maybe if you needed a large ratio like a two stage worm drive might be less desirable than this nutating layout esp considering the lower stress on teeth. Also mechanisms that might depend on specific gear ratios for timing, since your 1:409 ratio is super compact for that kind of specific extreme ratio
With just a pair of metal worm/gears in series like the ones you showed at the start, you'd get 1600:1. Metal, simpler, stronger, quieter, cheaper, so, ...! Great to explore this kind of stuff, though!
Its a matter of use cases. Most of the time you don't need a planetary gear, but when you do its very useful to have.
Same thing here, a worm drive is fine if you have the space. But if you are limited in space a design like this is nice to have.
Smart idea, but how strong is it? Will it be stronger than a worm gear set up, also what about long will it last under load?
Certainly a nice gadget but not a solution for real-life problems: the show-stopper is friction. *Properly designed gear trains have friction only in the bearings but never on the teeth* (rolling motion via evolute geometry). Here, there teeth are sliding into position. Big no-no in engineering and the reason why worm gears wear out so quickly.
That's wrong. Checkout the harmonic drive or the cycloidal drive. They are zero backlash drives and require friction on the gears.
Here's a good explanation of the harmonic drive:
ua-cam.com/video/7QidXf9pFYo/v-deo.html
That's not true. Involute gears have sliding and rolling contact. Pure rolling only happens at the pitch radius. Some sliding is a benefit in operation as it keeps the oil film from collapsing.
Even ideal evolute gears slide, this is plain wrong
Worm drives if properly designed with suitable materials and tribology do not wear out quickly. But it is so easy to make a badly designed worm gear.
@@zachary3777 Haha! Correct! Totally accept your response in the context of substantial forces & hardened steel surfaces. However, in the concept shown in the video, we are seeing a "dry" system built from a low-melting-point material. Here, we should aim at a system where we only see rolling motion & big radii if we want the system to survive for a reasonable time... self-lubricating materials would be a bonus too...
I feel like you could mechanically tether a counterweight to be driven by the same motor to oscillate at the same speed.
I think this kind of gearbox is used in some of the electric driven parking brakes in cars (usually at the rear wheels)
What an interesting little gearbox. Im sure theres a few applications for it
I could see this as like an Torque converter or smth like that mabye used in machines that has to run bit harder idk?
Can you measure gearbox efficiency by applying known torque to the input and measuring output torque?
A very pertinent question.
That is interesting. In a sense , it looks like a mechanical relative of the planetary gear, or even the differential, If the output is the center and you hold one shaft while spinning the other. Perhaps counterweights in the nutating gear would cure the problem of being out of balance.
Cool, another gearbox that acts like a cycloidal gearbox. I already have a functioning print of a harmonic drive and a cycloidal drive.
This is more like a split ring planetary
It’s an interesting concept. Have you done a comparison with a traditional gear with the same ratio for friction? I have a feeling the friction may be too high for practical purposes. Adding bearings to the shaft to reduce the friction there was a great idea, but as you mentioned in the video, there are multiple teeth meshing simultaneously instead of just one and that means more friction.
i love energy converters, does it gets hot? i like my ECs cool and chill.
This is great for high ratio needs.
Something like this would be perfect for a home telescope.
Some perhaps interesting ideas, a different tooth profile, like herringbone might be more forgiving and yield a more silent operation at a higher speed.
Alternatively, could you not just make the sides flat and simply surface the sides with a "sticky" material like an o-ring or silicon coating/layer? Are the gears even needed for it to nutate if there is sufficient compliance and friction in the surfaces?
I spent a bit of time working on it but I could not justify the cost of adequate tapered bearings for my experiment. They seem to work best when the input speed is relatively low but provide great torque in a fairly compact package, printing them is a problem because all the tolerances compound and you get a lot of vibration out of it.
are there useful applications for this with internal combustion engines?
seems like a fun concept but must be one helluva thing to balance properly
Try swapping the incoming and outgoing rotation. In order not to slow down the final rotation, but rather to accelerate it.
Is it possible to create a propeller based on this transmission mechanism ?
For example, for "pedal catamarans".
just a tought , dunno if this would work at all, but instead of adding a second gearbox if you make the two outer gears each half the weigth of the diddle gear , and then give them an oposite inclination to the middle on so when the midlle one force is maximum at one point the two other max out in the other direction ?, would put more strain on the shaft but i think its doable
Would it be possible to play with the weight distribution of the wobbling gear to make it stable? I guess that might be more dependent on manufacturing quality compared to adding a mirrored gear, but at least it would only be one unit
It appears you used involutes for the gears. Might a saw tooth or acme work better?
Maybe use a counter weight like in car engines crank shaft to balance the gearbox without adding a mirrored gearbox?
The video is very interesting, but I don't understand where this type of gear would be used, could you give examples of practical application?
I wonder if you can scale that down to be used in something like a model train locomotive? It could give it true scale speed operation smoothly.
The main advantage of a pericyclic gearbox is vey high output torque because several gear teeth are in contact at the same time. Because of its inherent design, we have this vibration problem causing the gearbox to self destruct. The only way to cancel out the vibration is by adding a "mirror image" of the gearbox. But then the output is now in the center of the whole gearbox which leaves us no other option but to use a spur or helical gear which is quite counterintuitive.
Nice video, thanks :)
I could really see this in some super low speed application that needs only torque. So you could stick a smaller motor on it and call it good. That 400-1 is crazy! and could be useful, just needs some optimization
I'm wondering about how it could be miniaturized - high torque, low part gearboxes with less tooth shearing could be quite useful in robotics.
Similar to a strain wave gearbox, it should have extremely low backlash due to the large number of teeth engaged.
Yes, but this design is much more 3D printer friendly. James Bruton did some experiments with a printable hamonic/strain wave drive but ultimately settled on cycloidal drives for his projects because of issues he had.
ua-cam.com/video/QoBgSWkJyM4/v-deo.html
Maybe someone will see a solution to the balance issue other than using a second gearbox and a better system of bearing (or maybe even something like a delrin bushing) might further improve things.
Yeah, looks interesting
Unlike strain wave gearing, this only connects at one area, until another mirrored part got added. Very similar mechanism indeed.
My husband would understand this. It is interesting. 😊😊👋👋❤❤
Same result as an "harmonic" gearbox used in robotics but this design shown would handle more torque due to the large number of teeth engaged.