Experiments with Cycloidal Drives

[@jamesbruton]

Version 2 of my Cycloidal Drive is coming up in a couple of weeks!

[@derkonsument7061]

hype is real

[@georgemathieson6097]

Genuinely really looking forward to it James, I love videos like this where you're experimenting and innovating with robotics.

[@lbonnel]

Crazy thing :) you are amazing ! Have you seen this guy robot arm with cycloidal motor kzbin.info/www/bejne/anrJeWxpfb6WptE

[@JClemente1980]

Why not a "normal" planetary gear?

[@MuhammadDaudkhanTV100]

Great

[@FrancoGrimoldi]

This is becoming increasingly challenging to follow. I like it VERY much.

[@HaloWolf102]

Strange, I am following along perfectly. Though I do have problems following along with all the jargon for code, and coding programs. This is a breath of fresh air for me, compared to the other videos.

[@514_cricket]

Im glad to see you working on the robot dog again

[@EngineeringSpareTime]

I’d like to to point out that this is not an actual cycloidal transmission, even the animation doesn’t not show it correctly. The cycloidal disc has a specific shape to it which can’t be designed with a basic cad sketch - nonlinear. It has to be calculated and interpolated (e.g. matlab to dxf to cad). I built a full metal version for a robot link myself (video..), there is no room for shape imperfections :) The actual shape will improve output speed consistency, load distribution around the circumference. In addition: Multiple disc will help to reduce load induced eccentricity and vibration..improve the efficiency (back drivability). As a hint: every roller has contact to the cycloidal disc at any position in rotation. Might seem difficult, it can be described - for “each“ position - by means of ruler and compasses though

[@LiyangHU]

Aforementioned video link kzbin.info/www/bejne/pqu3qHiObs51p5Y

[@rdyer8764]

Is there a technical name for this type of 'cycloidal' variant, or is it just a bastardized version that only works if the materials are somewhat compliant or have large tolerances?

[@EngineeringSpareTime]

@@rdyer8764 I‘m not aware of a suiting name. It somehow appears as a cycloidal without being a cycloidal :) The cycloidal itself defines a specific shape that’s created by rolling one shape in relation to an other one and tracking a point one the moving element- e.g. circle over circle or circle over a straight line.

[@rdyer8764]

@@antitriangular2828 That's pretty damn cool! I think that equation gave me a mathgasm! I love seeing stuff from people way smarter than I.

[@antitriangular2828]

​@@rdyer8764 Hah. Unlikey, I just happened to have been working on an anti-backlash variant of Paul Gould's work after printing his version last week. In fact, Paul Gould includes his inventor files and the equation is embedded in the defining profile for the disks. I ended up looking up and re-doing it myself because I don't like using equations I don't understand (also - I couldn't get the ratios I wanted to work correctly, and wanted to understand why!).

[@taterthepenguin]

I am in my 30s with absolutely no engineering background and yet I've somehow stumbled into Gear KZbin and I can't stop watching

[@DeepRafterGaming]

If you optimize your teeth design you can make it contact 100% around the cycloidal disc, that's where the real benefits are with this type of drive

[@YoTu77]

correct, I see no reason why this should not work more perfect with real gear tooth design instead of these round teeth. But certainly much more efforts. I have seen this only once. All other designers do it as you do (with the half circles as teeth)

[@marsgizmo]

excellent project 👌😎 very curious about V 2

[@kostasdrakakis8386]

Yes it is , ... *** family guy characters staring in your eyes ***

[@RobertSmith-me3gs]

kzbin.info/www/bejne/qpiogKOibZ1jga8 for V 2

[@rogerbarton497]

I started out in the computer industry as a field service engineer in 1970 and some of the mechanical contraptions around then were unbelievable, I found electronics much easier to follow. Here we are over 50 years later and I'm still discovering these amazing mechanical devices.

[@ericvauwee4923]

Yes yes yes, i love seeing These cycloidal bois popping up all over KZbin. I am currently working on an actuator where i integrated a 16:1 cycloidal gearbox into the stator bore of a 8108 BLDC motor to make it super compact.

[@ChrisBigBad]

the shift going from the small inner gear to the 10-leaf-clover was very easy to follow. well done mate

[@kingjamez80]

Absolutely fantastic engineering. This is the kind of video that inspires people to learn... well everything, physics, math, statics, dynamics. It's amazing what youtube brings to the world through intelligent creators like you.

[@mica4153]

This has got to be one of the best example of a 3D printed cycloidal drive already. definitely excited for two cycloidal discs and more bearings!

[@jamesbruton]

Thanks, it's coming up in 2 weeks

[@georgemathieson6097]

I don't know if I can hear it because of having young ears, but I love the high pitched sound that the motor makes when you were initially testing it - very cool.

[@ryo-kai8587]

I can definitely hear it, and it sounds awesome. If you can hear the high-pitched whine of a CRT TV, you can hear this.

[@CrimsonRegalia]

I was a vibration analyst in a previous life and these things are my worst enemies.

[@JL-pc2eh]

Thats nothing xD I saw CNC-machines that shook the building they stood in because they accilerated and stoped so fast^^ The building was checked regulary to withstand it but it was crazy. They once tested a machine not bolted to the floor and it moved like an arms length in a few minutes.

[@awemowe2830]

@@benjamin4321 veritasium has a video or two on vibrations

[@turbod1g]

@@JL-pc2eh Your run of the mill Haas has to be anchored to the concrete beneath because the rapids produce enough inertia to rock the machine when it comes to a stop. It is one of their huge downsides. Higher quality machines built with larger and heavier frames don't suffer from the same rigidity issues. Even if the Haas is anchored, the vibration from the lack of dampening will translate into surface finish issues on the part being machined.

[@samrevers742]

industrially they are built with multiple stages out of phase to counteract the imbalances, which he mention around 10:50

[@awemowe2830]

@@samrevers742 Found it. kzbin.info/www/bejne/qHbSlGOPpKZ_qpI It was Steve Mould

[@Twosies20]

I especially liked this video, James! The way you walked through the problem, iteratively introducing each part of the solution was very informative and satisfying.

[@wesleyooms]

A cleverly designed 2 stage belt system can be very compact and strong. The trick is to use a very small difference in cog diameter, have the second stage coaxial with the first stage, and then spin the casing that holds the cogs. So the casing becomes the input shaft, one of the cog shafts becomes the casing, and the other (coaxial) cog shaft becomes the output shaft.

[@a__duck]

Been watching Paul for months. Fantastic upgrade

[@vbtt]

The best revolution in James Videos!

[@jameshamaker9321]

I see what you did, there. It's a joke.

[@hardwareful]

It's time people switched to bearings pressed onto dowel pins. They're mass-produced precision parts, and all they need is a reamed hole in the plastic parts to receive them for repeatable interference fit

[@buckstarchaser2376]

That's going to be an unending joy, once your accellerometers get a load of 4 or more of these gearboxes.

[@jamesbruton]

Version 2 comes up in a couple of weeks with 2 discs in

[@sjorsschoenmakers3629]

I got interested in these Cycloidal drives to use for a self built CNC lathe for the C-axis. It would have to be clutched to the spindle when activating C-axis. I think you could use the same motor for normal spindle drive (high speed) and mechanically shift to C axis mode (high rigidity, low speed positional control). The reason to use a cycloidal gear is that it has almost no backlash and you can get very high reduction and rigidity (if made from something like steel, not PLA, and with tight tolerances). The point is however, on a lathe you often want a through spindle bore. The cycloidal gear would need to have a hole in the middle and I think I have found a way how to do it. Take a look at the output shafts. They basically are excenters aswell, so you could lose the excenter in the middle. Also those output shafts (that are the input as well) don't have to be inside of the cycloidal disc itself, but imagine a disc that does the exentric wiggly thingy (not actually rotating) and the cycloidal disc is "glued" onto it. Then the outer case actually becomes the driven output. Just some ideas. First idea works well in CAD, second one I'll have to dive in to and do some designing.

[@SaHaRaSquad]

I recently experimented with cycloidal drives myself because I find the principle really fascinating. I didn't do it with such a high-torque or clean design but here's two interesting things I discovered: If you use a correctly calculated cycloidal shape with well-tuned tolerances you can *drastically* reduce the eccentricity(wobbling movement). This not only reduces the strain on the motor and other parts, it also allows for more compact designs as - like you showed in the video - the holes for transmitting the movement from the gear to the output shaft depend heavily on the eccentricity. The drawback of this is of course that tolerances become more significant. The second thing is probably not as relevant for your project because it's more suited for high gear ratios and hurts the ability to backdrive the mechanism, but double-staged cycloidal drives can be simpler to print and build as the output is automatically a non-wobbling rotation without the need of this transmission via holes in the cycloidal disk. So it can again be made smaller. I combined those two aspects to print a tiny double-stage gear with a ~1:1000 reduction, with an eccentricity of just 0.6mm! It's not very practical but it was more of a quick feasability experiment and a lot of fun to make, and interestingly works more smoothly than my failed first try using a single stage.

[@warboat1]

Cycloidal drive is basically a lob sided subset of planetary gear drive method. Planetary gear set so much stronger, balanced, tighter, efficient and reversible.

[@heyitsthatdude17]

Really interesting video as always James

[@MrAdzielinski]

I knew you would get to cycloidal drives eventually. Amazing work.

[@martinsmith2948]

super cool stuff, you are a master of design

[@shaun6828]

Pretty cool to see one of these built dogs home built.

[@Here_is_Waldo]

That's really neat! I'd never even heard of a gearbox like this, I just thought it was going to be a planetary gearbox. Thank you for introducing me to a different type of drive that can be 3d printed, and looks so interesting when it's running!

[@frederickbowdler1509]

Fantastic product excellent staying power i am in awe!!

[@Redneckmfg]

James, You Boggle my Mind more and more with every Video you Post... Your a Modern Day Genius to the power of 10 !!!!

[@matthewarchibald5118]

2:16 you quoted stratus productions as that video source which is technically correct as that’s the url, but the channel name is rctestflight

[@-repkid-4724]

what he said

[@zaggery]

Yip I was confused. Had no idea that was his channel url as the video links are always shortened kzbin.info/www/bejne/h4fIoWyfiL2Jm9E

[@bragr_]

Weird, I was sure for second he was crediting a freebooted version of the video. The more you know

[@fauxjito7402]

Fantastic video! This is a brilliant explanation of both the function of a cycloidal drive AND your thorough design and iteration process. Really like it - looking forward to seeing v2!!

[@Exerkitus]

I absolutely loved this! Your channel inspired me to study engineering and this video really reminded me why I made that decision. Thank you!

[@Steve_Just_Steve]

thats by far the best 3d printed one I've seen!

[@harryman01]

You have a cnc router, why not use that and cut all the parts in aluminium Even might be smaller than 3D printed

[@jamesbruton]

I really want to make it accessible. If I can make it 3Dprinted, then I can always upgrade later.

[@atharvbhalerao3062]

@@jamesbruton this is patent worthy

[@titter3648]

@@atharvbhalerao3062 No Cycloidal Drive have been in use for a weary long time. Nothing novel here.

[@DerKrawallkeks]

@@jamesbruton I'm really thankful for that!

[@taleg1]

CNC mill a version of it out of metal when you have a model that works like you want and use that to make it both smaller and more solid. Epic cycloidal gear by the way :D

[@santosvella]

I came here to tell him that too. I love my 3d printer but there's only so much its capable of. Gears not really one of them for this.

[@Francois_Dupont]

@@santosvella he want to make his robot 3D printables.

[@taleg1]

@@santosvella It's good if you want to do testing. One you have something that works, then you go for the milled metal parts. If that works or not, you tweak it, rinse repeat and soon you have your working device or prototype.

[@santosvella]

@@taleg1 Yup, that's what i use my 3d printer for. Wish i had a cnc though.

[@taleg1]

@@santosvella Maybe one day soon we'll get new 3D printers that are able to do multi materials that include ceramics and metals. I know we can do that now with some really expensive gear, but imagine what we could try with 3D printers that could created items of durability. I saw this demo of a very very custom and very advanced 3D printer being researched that more or less could do any material. It could even do 3D milling. It was insane and the cost was in the millions. But we'll get there one day.

[@avejst]

Great design Thanks for sharing your experience😀👍

[@PatrykAndrzejewski0]

Insert another rotor (yellow) on offseted 180degree bearing on the motor shaft this will neutralise most off the vibrations

[@JohnJaggerJack]

If you use prime numbers of teeth for the gears you can get the teeth to wear out more evenly.

[@ziad_jkhan]

Glad I came here looking for potentially useful comments

[@JohanDegraeveAanscharius]

The best version I've seen so far!

[@swannschilling474]

Hey, I did a version of a Cycloidal Gearbox with all printing files available and a Fusion 360 script which lets you create the reduction ratio on the fly... it is backdrivable! I am a big fan of Cycloidal Drives! Keep it up!! 😀

[@makerbeelab5546]

Hi James, you can totally get to 10:1 reduction if you use a pulley force multiplier. Essentially if you replace a big pulley with a large bearing fix one end of the belt back on the body while putting an idler on the leg so that for 2 times the movement of the belt you will have 1 time the travel of the leg.

[@Will_Huff]

I am so glad you are designing and testing these types of gears. Dare I say you are putting the ole Bruton spin on it (pun intended). Looking forward to next version!!

[@hunter00047]

Wow you're on another level, amazing well done.

[@Mkidcraft]

Since I recently got a 3d printer, I now fully realize just how much you are able to get done on one within a week. A lot of my prints have averaged at 24 hrs per print. But even with smaller prints, they take longer than I thought. You have several printers now to help you get more done, but even with 1 printer, you seemed to work fast.

[@dekutree64]

Try 1mm nozzle and either .25mm or .4mm layer height, 45mm/s, 210-220C for PLA. Thinner layers allow steeper unsupported overhangs. Supports can add a lot of print time and material use, so design to minimize them. If you have something high up on a model that needs support, see if you can build one in that angles up at 45 degrees from a nearby surface. Much more efficient than a tower all the way from the build plate.

[@ArnaudZANETTI]

For a similar result, but with everything running perfectly "round" have a look at "Split-Ring Epicyclic Gear" (or "differential epicyclic gearset", "compound-planet epicyclic", lots of names for the same device). It is also back-drivable (but there is more friction). You might also consider the "Strain wave gearing" that is also compact, has massive reduction-ration and no backlash (and is supposed to be back-drivable, even if this doesn't seem obvious) ; it is 3D printable but requires one "gear" to be printed with TPU or equivalent, because is relies on deformation to transmit the motion.

[@Kyocus]

I can not express my happiness and relieve when I looked right and saw "Cycloidal Drive V2"

[@jamesbruton]

There's also a better testing video that was published a couple of weeks later.

[@NapalmSticksToChildren]

i subed and liked just because this video made my day and was super wholesome

[@jamesbruton]

Thanks, V2 is coming up in a couple of weeks.

[@GregorShapiro]

Me too!

[@literate-aside]

Loved this. Looking forward to v2.

[@shashanksharma6881]

This was very informative. It helped me with the exams. Thanks!

[@julienpepin6]

Such a very elegant design you made, Bravo !

[@impuls60]

You can use M3 of M4 bolts of 12.9 steel quality instead of M6 overkill bolts. Smaller bearings would also allow you to make the device much smaller and lighter for a better impulse response. Looking forward to see it in action!

[@jamesbruton]

All the bolts are M4

[@rajuyadavk5812]

Way of explanation is high level sir

[@frogsshadow4189]

Since you're sticking the shaft through the center with a cam To stop the vibrations you could mount a weight on the shaft that matches the weight of the gear and stick it 180⁰ out of phase. That way you don need a crank that has to go through two gears. Though getting them balanced perfectly would be difficult. (but you do have the sauce for that in the current design due to the cutout hole)

[@tomboyd7109]

Mounting the bearings on shoulder screws instead of bolt threads works nicely. Properly shaped gear teeth would probably help too.

[@charleshughes2683]

Hey man great content really well explained all throughout. Also loved the modelling you did for the wallet ;) take care

[@OtherDalfite]

Awesome video. Excited for the next episode! Subbed

[@machinesandthings9641]

That’s pretty damn impressive sir.

[@sabrinazwolf]

Nice job James! I love watching your robot videos.

[@OleZZ222]

Consider, bearings without sealing with less friction probably better suited for this project. Great job!

[@technoandrew]

You previously had issues with the motors in Opendog 2 heating the plastic, so you fitted those metal plates to dissipate the heat. Might be worth doing similar again.

[@jamesbruton]

Probably, although this is 10:1 and the belts were 5:1, so I get the same torque for half the power/heat.

[@marco_gallone]

I love this design!

[@fluffylynx6643]

It also has the bonus of sounding cool as hell, come on, I saw this video and thought you were going to be making a spacecraft haha

[@magnus4437]

this is what I call a great youtuber

[@owenwilson3750]

Im no engineer James but I am a mechanic and we use molybdenum disulfide grease for CV shafts, diff installs and I rebuild my old tools and use it on the sintered gears. My theory is because of the nature of that shit, moly grease should be perfect for a 3d printed gearbox if you use hard-wearing plastics because it'll soak up into the print lines and it sort of embeds the gears with a harder metal so they last longer. I don't understand this as I say I am a humble mechanic and I know near to nothing about 3d printing but I hope that this may help in future. Love Owen.

[@OliverMotorized]

What type of filament do I need to 3d print those belts in the beginning?

[@alt.animate]

that's really cool. like 3d printed version of a mazda rotary engine in reverse, and rotary engines stack together with offset crankshaft too.

[@ReiverBlue1971]

Wonderful stuff! You got me hooked with the balance gyro ;D

[@JulianMakes]

Awesome! Im so impressed it’s back-drivable

[@rpavlik1]

What a really neat design!

[@TheAstronomyDude]

Super cool! I've been trying to make my own cyclodial drive for a tiny jumping robot for a while now.

[@patprop74]

James, I am just sharing my input, take it as my opinion and nothing else, You know I have been following your channel for a very very very long time, this video and last few for that matter, the way you have been producing (and or scripting) them, they are sounding more and and more like a Tom Stanton video's, There is nothing wrong with Tom's videos he has his own thing going on, he is just not everyone cup of tea, you have almost 1M subscribers because of your energetic energy and your brilliant approach to accomplish the project at hand, which was reflected in the way you made your video's, that is why we are all still subscribed to you, you are so close to the 1M, now is no time for to change. I and the many thousands of us, that have been subscribers before you had even 100k subs, all want to see you hit that Millon sub.

[@jamesbruton]

Hey, yep trying to find a balance (but also fix the low view counts ;-)

[@patprop74]

@@jamesbruton It is none of my business to suggest anything, as you have already surpassed our expectations and then some, James, you have shown us years ago how brilliant, you and your approach is, you have nothing to prove to us, we already know all that about you. I do understand your point, So perhaps the answer you seek is in the past, as of late, your average view count per upload, has been somewhere between 50k to 90k some a little more some a little less, however, go back 2 or 3 years it is more like 90k to 200 plus k, Perhaps it's not your "balance" but the projects? don't forget most of us AKA the loyal subscribers that have been around for the last 7 or 8 years, are old dogs, we need to be stimulated with diversity loll Take Collin, for example, none of his video's features the same project more than one or two video's, sure he will go back and revisit them now and again. IDK Perhaps bring back that Arty hottie maker friend of yours, on videos more often, mix it up a bit, nothing brings views like a hot maker chick as an assistant haha. JS, James, your videos will always get a like from me.

[@walterbunn280]

Ehh... So with regards to strengthening the plastic parts, in general, you can add high strength epoxies. If you get the right epoxy it offers a smooth, wear resistant part that the force of the movement can work into better than raw pla/abs/nylon. With regards to keeping the gear the same shape, instead of using a smooth bearing, you could use a v-groove bearing. If you go this route, the v, or rail, that the bearing rides on will add to the diameter of the 10 toothed gear, which might allow you to keep the gear the same size. In addition to that, you could use an aluminium liner inserts. A small piece of aluminium lining the hole that the bearings rotate on seems fairly straight forward for adding strength, and, if you can find a small novelty can of soda that matches the diameter of the hole you need, making it seems super cheap. Even if there isn't a canned soda that matches, you could just find a piece of aluminium pipe that does (it comes in many sizes), it might add a small amount of cost, but since you need such a small amount of pipe ( the depth of the gear in the thinnest plane times the number of holes) it should still be cheap. Like, assuming you're bad at cutting pipe, you still have to buy pipe in discrete units depending on length, usually a meter (around 3ft) at a time; you shouldn't need more than a single unit of pipe.

You could mill an aluminium part to replace the one that broke. Some things aren't meant to be 3d printed.

[@MrHantz101]

1:21 - those headless cricket dogs are terrifying

[@smokey04200420]

A better ratio formula would be (Bigger/smaller)-1 or (B/S)-1. Easier to write. Easier to compute with a standard calculator. Less mistakes will be made.

[@seanregehr4921]

Make the cam shaft out of metal. Instead of a straight pole off center, make a centered pole with a kink. This will also make it simpler to secure on the other end. The craftsmanship is good enough as is for the rest to hold up to higher torque.

[@nicolassimard5847]

This is an absolutely brilliant job. Well done 👍 Very interesting video, well edited. Thanks for that

[@SpencerPaire]

This is so cool! I've been thinking that cycloidal drives would be perfect for OpenDog for a while, but I always figured either there was some missing feature or you'd get around to them eventually. I'm really excited to see V2!

[@parthpatel9602]

For measuring torque you can get those spring weight measuring tools and hook it to the handel at 90° and then lett it run you'll get the torque.

[@lohikarhu734]

at 15:04, I can see some damage to the cycloidal plate, and, when running, the backlash appeared to come from a very poor fit of the motor cam drive bearing in that cycloidal plate... tolerances!!

[@AlexanderTzalumen]

Looks like the cam sheared at the layer lines. A high stress part like that might need to be printed at 100% infill and remelted in salt to get uniform shear tolerance.

[@ThomasRonnberg]

the quality of these videos is astonishing.

[@nerd1000ify]

You could save a lot of space by replacing the ball bearings on the ring and the output disc with plain bearings (aka bushings) running on smooth steel shafts. They can be 3d printed from nylon or graphite filled pla. Obviously this arrangement will have a shorter service life and more friction but the cost, size and weight savings may outweigh that, especially since well designed plastic plain bearings actually last a really long time.

[@jameshogge]

Think this could use some M10 smooth rod: - Ditch the exterior bearings and run the rotor directly up against the rod. Rotot on steel + silicone lube should be fairly low friction - Same for the bearings inside the rotor: just put small smooth rods through each hole - Finally, even the centre axle could be replaced. Then add a 3D printed cam and drill a fixing bolt through the rod = smaller, fewer parts by ditching all the bearings and easy enough to build if you have a rotary tool with a cutting disc

[@crayder1100]

This would make a good bed shaker alarm. I'd buy one.

[@bobthompson4319]

awesome design . it looks like the clutch on an atv or motorcycle. lol

[@hoah]

You can push the output pin on brushless motors through the body, to convert them to work inboard rather than outboard.

[@jukkapekkaylitalo]

This japanese invention used in Hajabusa blanes. Usually has two inner teeth in 180° ankle from each other to reduce resonance, and tear when there is allways atleast 2 inner teeth touching outer teeths in opposite sides. The durablity is better.

[@recklessroges]

I thought that cycloidal gear reductions couldn't be back-driven, but I was reaching that conclusion based on OskarPuzzle's "11 million to one gearing". It's nice to be able to update my mental models.

[@enriquegarcia7613]

Amazing work as always!

[@nic0fpvnicolas606]

You should increase the overlap between walls and top surfaces on your slicer, because you 3d print has holes. It will make then stronger. (In cura I use 30% but the setting really depends on the slicer you use)

[@aoverhage5181764]

Might also try a stain wave gear / harmonic drive setup. I have seen them made with timing belt. Seems light there might be less to ware with that setup? Look forward to version 2.

[@jamesbruton]

Yep I'll be trying that too, although they don't back-drive well.

[@aoverhage5181764]

@@jamesbruton True. Holding is one of the "features". Maybe not in this case though :)

[@hypercube33]

Epic levels of under extrusion on those prints dude

[@vide0viwer]

The sound for the cycloidal sun gear is a bit noisy, you could try to change to using Alloy 910 nylon filament with a petg core to reduce the noise and wear. With your bearing design I doubt there would be any wear with nylon.

[@outofthebots3122]

I look forward to seeing version 2. I certainly think once you sort out some of the bugs and create a good design it will work well for lots of your projects.

[@CMBProjects]

This is very nice!! Great job!!

[@PrinceCharles23]

i like the detours in no-so-common-ground but still do not really understand why this design is easier to follow/rebuild/source than a planetary gearbox

[@thereal-stl_slim]

Magnets instead of bearings. No friction=no wear. Great video!👍

[@lucalauro_]

And try to lower the eccentric offset, it would make it more solid and efficient, less vibrating but a bit less back drivable i think