120Nm 3D Printed Cycloidal Drive

Ad: Thanks to PCBWay for sponsoring this video:www.pcbway.com/
Do you remember when I built openDog version 3 and I designed cycloidal drives - there’s 12 of them in that machine and it’s still going strong. The motors are brushless motors controlled by ODrives and I‘ve got some more projects coming up this year using the new ODrive S1 servo kit which you’ll see in the next few months.
I want to build some much bigger machines though, which will probably move much slower, and I also want to make the designs accessible.
In this video I’m going to design a Cycloidal Drive using a DC brushed motor which already has a gear head on it, and if it goes well I’ll be using it to build some much bigger machines later in the year.
CAD & Code: github.com/XRobots/CycloidalD...
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Huge thanks to my Patrons, without whom my standard of living would drastically decline. Like, inside out-Farm Foods bag decline. Plus a very special shoutout to Lulzbot, Inc who keep me in LulzBot 3D printers and support me via Patreon.
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Below you can also find a lot of the typical tools, equipment and supplies used in my projects:
Filament from: www.3dfuel.com/
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Bearings from: simplybearings.co.uk/
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CAD content is sponsored by Autodesk Fusion 360

[@FaffyWaffles]

Open Dog is one of the coolest projects on the internet

[@Alessandro---]

James Bruton IS possibly the coolest creator on the Net.

[@NealFosterHD]

Has anyone else made one from his designs?

[@wktodd]

You might have room in the hub for a third disc to give three phase drive . That should prevent the cyclic load that you're hearing. You might have to split the cam to get the bearings on.

[@Fabian3331234333]

The belt is actually quiet genius, as it's limiting the torque and prevents the gearbox from exploding

[@GaryTheRCcar]

I think it's better for the motor to just stall, the belt will wear out real quick shipping like that.

[@ashtonhoward5582]

​@@GaryTheRCcar but the belt is cheaper.

[@Unmannedair]

Belts are basically mechanical fuses

[@conorstewart2214]

@@ashtonhoward5582 Just current limit the motor, you can limit the torque then too. A motor stalling isn't necessarily bad, its what happens after it stalls that is the problem, like continuing to run current through it and at that point it is just a resistor.

[@GaryTheRCcar]

Just because the motor stalls doesn't mean it will break. as long as it doesn't overheat it will be fine. He can limit either the voltage or current to achive this@@ashtonhoward5582

[@BlizzyFox]

My favorite part of these videos is when James puts his hands in places where the 3d prints can crush him

[@MattDunlapCO]

Holy crap. I was whole-body cringing and holding my breath when he was trying to stop the drive with his hands.

[@AJ-Palermo]

I was thinking the same thing! With the 20:1 gearbox that's over 4500kg/cm!! A finger probably wouldn't even slow the motor down! It'd be a slight increase in current draw and a significant decrease in fingers!

[@MattDunlapCO]

@jamesbruton, please do a follow up where you feed meats and various other objects into the gears or between the belt and idlers! Another demonstration showing how much more dangerous these machines are when wearing gloves would also be fun.

[@AJ-Palermo]

@@MattDunlapCO that's a cool idea! I know firsthand (pun intended) how dangerous gloves are around machines with rotating parts. I work in a warehouse with conveyor belts, I'd never stick my hand in anything, but I was curious and stuck just my glove between the rollers, and even though the rollers lift up so they don't crush your fingers, there was still an impressive pulling force on the glove. If you were to stick your finger in there, it would definitely hurt, but you wouldn't lose it. With a glove on, especially a grippy one, you could easily lose your fingers or hand, maybe even your arm!

[@MattDunlapCO]

@@AJ-Palermo my daughter may have lost fingers to a drill press if she'd had on gloves tougher than cheap cotton knit. Thankfully the material failed before her hand.

[@noahwomack9929]

Great video as always James! For once I might be able to help you out with a design. I've been working with a university rover team to design and build cycloidal reduction drives for use in our 5 axis rover arm. The idea you tried at the beginning of the video is actually what we're currently using, with the output of the gearbox being the housing of the cycloidal itself. If you'd like to take a look at our cad or ask any questions about it's performance I'd love to have a chat with you about the subject.

[@kimtae858]

He doesn't read comments after the first few hours of a video going live. Twitter or Instagram are better places to get his attention, but be succinct about it. He doesn't read long messages, lol.

[@Hawk7886]

​@@kimtae858pretty sad really, the comments are great in videos like this

[@davidcatanach2620]

Feel like he’s just phoning it in

[@WarwickAllison]

His joke is getting very old. But he'll keep doing it to generate all this pointless "engagement" as his channel goes down the toilet with all the other meme-chasers.

[@WolfmanDude]

@@WarwickAllison Why are you so mad about a minor visual joke in the intro? Not even normal mad, your comment reads like you are about to strangle someone :D

[@ionkill43]

@@WarwickAllison It's his microphone

[@FrodeAltink]

No, it is not his microphone! His microphone is on the neck of his t-shirt. The phone is just a prop. And I am loosing my focus half way through the video because of that stupid phone. Please, just stop using it.

[@WarwickAllison]

@@WolfmanDude Bored of it rather than "mad". Every KZbinr doing the same joke gets boring fast. I actually like that he's doubled-down - helps the meme run its course quicker.

[@Xailow]

Giant open dog/AT-AT? Brilliant design!

[@excitedbox5705]

To put the motor inside the gearbox you need to "cup" the motor with mounting points around the lip of the cup and the shaft through a hole in the bottom of the cup. Then you can put the bearings for the cam shaft around the cup. Or look for a motor with mounting points in the base. The size of this drive makes it kinda impractical, but it did lift 2 tons at 1 cm. Maybe going with 100% infill you can shrink the size a bit.

[@erictheepic5019]

>Or look for a motor with mounting points in the base. Or he could *make* mounting points. I'm thinking either a battery spot welder or a (reversible) adhesive.

[@lukedoesnotlie]

The first cam which incorporated the motor was beautiful.

[@HelenaOfDetroit]

Having been watching you for almost a decade it makes me smile to see you learning and using mechanical principles. You've always been an amazingly talented electrical engineer with computer programming and maths skills beyond my abilities, but as I'm more inclined towards mechanical engineering then some of the earlier designs were sometimes difficult to watch. Nowadays though? Nothing but smiles! You've grown so much and you're getting so good at mixing the two specialties together to design and make incredible objects. Keep up the amazing work James! Thank you for sharing so much of your hard work, progression, information, knowledge, and passion.

[@jamesbruton]

lovely thanks!

[@patrickjdarrow]

Really love this kind of video that focuses on practical and fundamental elements James!

[@Gregulations]

Wow this may well come in use for one of my next projects! Thanks!

[@jeremyniemiec9252]

hello, you helped to inspire my senior design project in which I developed a 13:1 cycloidal. To reduce weight SLA printed bushings where used and they worked great!

[@Eddesignful]

That is a monster drive. Keen to see the project that needs it.

[@RiderRickMaker]

Made my first cycloidal about 3 years ago... milled and 3d printed with servos... that thing was savage. But..... metal is metal! :) Excelent project tough!

[@soodonym]

I enjoyed that immensely. Thanks.

[@rommelfcc]

😊 very satisfying to watch cycloid gearbox drives 😊 💖⚙️💖

[@GrayGames1542]

nice to see your still doin stuff

[@matthewrennie1110]

Bro I swear you have the bast ratio of skill, dedication and talent. Doing a couple of my own projects right now but definitely planning on making an open dog at some point. Keep it up man love your videos

[@AJ-Palermo]

And creativity! He comes up with really intriguing ideas!

[@tHaH4x0r]

For your first design, the problem with your wobbeling is indeed with the motor itself, but not necessarily with gripping it. Essentially you have an overconstrained problem here. On one hand, the discs (through the frame and bearings) want to determine the center of rotation, and on the other, the motor wants to fix it as well. So what you would want to do, is release certain degrees of freedom keeping the motor in place, and only constraining the DOFs that you need. In this case, you would want to constrain rotation around the motor axis (otherwise the housing would turn as well), as well as translation along that same axis. You probably want to somewhat release the other two rotational degrees of freedom, although they are of lesser importance here. What is most important, is that you release the two translational degrees of freedom. That would allow the motor to 'self allign', and to 'track' the center of rotation. This would prevent the thing from wobbeling loose due to excessive forces, and likely also fix that flexing issue of the outer case. That second design, the belt essentially fixes this overconstrained issue. It is pretty compliant in those translational DOFs (and rotation as well).

[@sydnerd]

I really love that something as simple as the belt tension can be utilized as the max lift safety-limiter to avoid breakage of other parts that would break otherwise. Go Open Dog!

[@faeranne]

A very nice build that's well explained, but I gotta ask... wasn't the intent to keep the motor inside the hub? I feel like about half-way through the video, the goal was kinda lost there. Might be worth re-tackling the original concept again, cause I'd still love to see a successful through-motor build.

[@DanJanTube]

mind your wall thickness when you're designing those 3d parts. and use a inside radius whenever possible, carries the strain better than a sharp corner

[@aserta]

You can still have it in the center, just go to a larger bearing and make a casement that brings mounting points to the back of the gearbox (of the motor).

[@TheGeniusSavant1]

That's exactly what I was thinking. At 3:48, it looks like it would be no problem to extend the sleeve and add mounting points at the back of the motor near the leads.

[@leptok3736]

​@@TheGeniusSavant1third along the lines of: Was thinking, could he increase the diameter of the collar he puts around the motor to run some tubes along the motor back to a solid foundation? Then everything else is the same just with the center diameter enlarged to accommodate it?

[@Wizarth]

I think a simple thing that would make these projects easier is a big switch for turning on & reversing the battery power. You could even make it comically large, so you can throw it forward/reverse with lots of visibility on the camera.

[@CollectiveSoftware]

I love that solution for making an effective huge bearing out of plastic and small bearings

[@vell0cet517]

3d printed cycloidal drives always get me excited. I think they're going to play a major role in affordable robotics. One thing I will say about your design is that large bearings are expensive and heavy. I also get that sometimes you have no choice. Great video and I'm looking forward to what you're working on next.

[@technologyhobby]

I recently rebuilt a 4 tonne excavators final drive which is a very similar design to yours, but with a planetary gear set at the end, and three cam shafts spread out around the cycloid gears rather than a central cam to create that walking motion. The strength and reliability of these cycloid gear designs is incredible!

[@ed.puckett]

I first found your channel during the "Iron Man" period, and you never stop impressing me with what you are able to accomplish!

[@BloodyMobile]

I'm genuinely impressed it managed to do 200 NM for a moment and the only thing that "broke" was the belt no longer being tight enough.

[@jamesbruton]

yeah

[@davidhannan2672]

A fun thing you might try with the phone is to swap the earpiece and microphone leads in the jack, and then speak into earpiece. It will sound more like what you would expect a phone to sound like. Its not the microphone that gives old phones that characteristic tone, its the speaker

[@killingtimeitself]

its also the phone network, as well.

[@Micreathonn]

you amaze me every time

[@pruthvimeka3259]

to stop the wobble and the mis alignment once in motion, you can screw the 2 cycloidal gear parts together while maintaining the offset. that restricts the wobble while achieving motion that the cycloidal gear system is supposed to achieve.

[@lucasrogers8021]

I'm building one of the Open-dogs right now.

[@jessiejames3029]

post a video!

[@jac2206]

So Impressive, for a 3D printed cycloidal. Everyone who still thinks 3D printing Is useless, should Watch a James Bruton video

[@ws6002]

Well done.

[@nevernether3368]

"Assign a point of failure or it will assign one for you" -engineer somewhere

[@RGD2k]

Great work as usual.

[@RGD2k]

I did wonder about changing the offset on the two cams from 180, to 180 - 1/4 * 1/21 * 360 (about 175.71 degrees), the idea being to stagger the two cycloids so the engagement/reengagement cycle is a 1/4 step apart rather than a 1/2 step apart. (quadrature rather than antiphase), which I'd hope would be almost as good as going three phase for getting the oscillating torque (and load noise) to be steadier.

[@someguy4476]

This is awesome

[@ManlyJack]

What's with all the recent videos being phoned in?

[@SCU3A_S7EVE]

@@MaariSuave- r/woooosh

[@UptownBoogieDown]

Boom boom tsck

[@Maltese82790]

I know so little about any of this, but I look forward to one day seeing you post a video about how you have made your very own Mech Suit.

[@RinksRides]

120Nm?! From Plastic bits?! Are U MAD?! Cool gearbox, like the smaller bearings round the perimeter, I might S.T.E.A.L. that part of the gearbox in my own design. Not sure if that's more eco or just machining 5mm ball grooves between inside and outside housings.

[@timehunter9467]

This has to be one of the best projects on KZbin right now, I need to learn more about programming.

[@joinslayer]

That's a big servo! 😋

[@TradeWorks_Construction]

I liked the circumferential bearing solution, using multiple smaller bearing held into a grove rather than using a single massive bearing or bushing. I’ll remember that trick going forward.

[@Advil1024]

The most powerful 3D printed servo on the planet. Time to make BIG robots.

[@TheMeditron]

Wow, that drive is so impressive! I keep thinking it would be sweet to see you build a scale version of an AT-ST, that drive might work in the joints?

[@gcl2783]

You're a gem.

[@preferredimage]

Really committed to that phone gag..... :)

[@filemorf]

More like :( getting old fast, find it distracting, I will be skipping ahead here and there to reduce my view time. Too bad I usually enjoy and look forward to his content. Hopefully just a quick fad of a meme and over with it soon. I don't want to keep talking about it either due to the Striesand effect.

[@GooopGoooop]

@@filemorf imagine being this emotional over an insignificant prop

[@_DML_]

I love how everyone uses the time-tested "can't stop that with my hands" method to show that something is awesome and will be useful.

[@wecirclethesky]

Nice James

[@avarig]

nice job🎉

[@rikschaaf]

Increasing the belt reduction (if only a little bit) would also make the belt more tight.

[@quacker8230]

hey james, i noticed how cleanly some of your parts fitted together and I was wondering what offset you would use for say fitting a circle within another circle? thanks tyson:)

[@eski5195]

For 3d printing your big parts, i'd suggest a 3d infill like cubic or gyroid. It doesnt add much time and make parts somewhat isotropic and more tough

[@CleverGoatee]

OH YEEEEEEEEEEEEEEEES ANOTHER VIDEO OF CYCLOID DRIVE THANKS

[@mrwoodandmrtin]

Brother, you are getting pretty blase' about putting your hands around highly geared moving parts. You really need to check yourself. This stuff is now getting finger mangling strong. You need new safety protocols.

[@Hawk7886]

Yeah those pinch points would blow up fingers like hot dogs hit with a hammer

[@The12gaged]

Ya. Ngl, even though I knew this was posted and nothing likely happened, I clenched when I saw that. It not being bolted down, with the self collision issue, while all the sketchy finger work was going on was a recipe if i ever saw one. Glad it went like it did.

[@BouncingBallGames]

Ooof that was painful to watch.

[@Fanny-Fanny]

I disagree. I think it made it more exciting

[@mrwoodandmrtin]

Good point.. It's just a bad ROI in my honest opinion. Entertaining you briefly in exchange for the premiant loss of a very useful fingertip. @@Fanny-Fanny

[@steffen1182]

wats up with this red phone? I dont get it! 🤔

[@AnonymousAnarchist2]

Cant say why hes using a microphone inside a bright red phone, however I can say bright red phones have an association with important direct lines for a kind of neato oddball humor.. ish. I fail to find the humor myself but he seems to be enjoying it so.. meh.

[@gregarnold7516]

I love all of your videos. It would be awesome to see what you could come up with if you made a 6 DOF motion platform.

[@andrewslater6846]

If you have a method of measuring the concentricity of the motor housing to the shaft, you might be able to find why it was warping the outer ring. I think if you could constrain the cam shaft radially and just have a torque arm to prevent the motor from rotating, you would eliminate some tolerance stack up. But a torque arm would only work well if the motor was securely attached to the cam shaft (taper shaft or bushing) more than just a key and screw. Which isn’t really common for a 10mm shaft. But basically you reduced the number of axis you need to have tight concentric alignment by having a belt drive.

[@CrudelyMade]

if you put a support bar between the motor on the shaft side and the center of the gear, it should keep the plastic from bending and moving the motor toward the gear, keeping the belt as tight as it is initially. it's really jsut a space that you might be able to put on/off, I don't think it'd have to be super duper sturdy to work, with the way it'd be arranged.

[@piotrnod6489]

That belt slip could be a safety feature, so your new entrance barrier (to the parking spot at your house maybe) wont kill anybody xd

[@terencem9962]

I really appreciate folks that contribute significantly to open source technology development. So many smart and talented people do, and the world is way better because of it. I think the mentality people have to developing technology openly and collectively is a superior way of existing than the purely capital and greed driven alternative. Sure capital and greed driven projects have given us a lot, but had these been open source developments i think the world would have advanced much quicker. Look at 3d printers. It was only the expiration of patents that saw the technology really take off, and even though prior to that systems were available to those willing to pay, they were so few and far between and too prohibitively expensive that they really weren't the great contributors to productivity that modern 3d printers have become. Maybe i am wrong about this. I only know the pub science facts, but that is my take on the whole 3d printer patents thing.

[@ceerstar851]

I like to see the mistakes and fixes.

[@crystaldragon141]

you could probably put the belt side in double shear with one more plate. It would be nice if the motor had a longer shaft so that could be supported as well.

[@whatthefunction9140]

beast

[@sharkyshark1]

You could always brace the motor mount to stop that flexing to allow you to take it higher before it flexes again.

[@Z0M8I3D]

That poor-man's big-bearing seems like a good solution for the flexing. Too bad the back end of the motor isn't keyed for a better inlayed holder for that center drive idea to work but with the second version (including thinner profile & the guide bearings [poor-man's big bearing]).

[@Machine1136]

I am vexed and flummoxed by the phone.

[@jamesbruton]

I am speaking to you

[@dekutree64]

I can't believe how well that second one worked while still having the skinny ring. I've always proportioned them with OD = 1.5x disc diameter, whereas yours looks like 1.2x.Taking some rough measurements from a screenshot, I think that would make the solid ring (excluding the teeth) about 3x thicker, so 27x stiffer. Maybe I've been overdoing it...

[@nekobyoneko444]

I'm curious if this could be a feasible option for something like a (relatively) slim high load elbow joint for a mechanical arm alternative to hydraulics. Seems like if it was made of sturdier material then it could move a heck of a lot for such a small setup. Either way looking forward to see what you do with it in the future.

[@nlingrel]

Seeing it back-drive with the long lever arm made me think about a water wheel for generating power.

[@QIKUGAMES-QIKU]

You seem to be still stuck on Hold every video 😁

[@JessWLStuart]

If James Bruton was on Gilligan's Island the castaways would have been home by the end of the first episode!

[@cbs1556]

So much work being put into something that will last 3 months of continued use maybe. I wish you would implement more aluminum T slot frames to negate some of the slop in your material of choice. just plan your 3d prints around the T slot frames and you would run into less issues.

[@Pillazo]

I'd be very interested to know how you design the belt sprockets! I have belts but no idea how to design the sprockets for them to run on.

[@ihydf]

Sweet! Now make a harmonic drive with a spline that isn't made of jello and a wave generator that doesn't just support the spline where the teeth engage!

[@buzz1ebee]

Ah the genZ youtube style of holding a headset whilst talking. Love it!

[@weirdsciencetv4999]

Could you please do an episode on dynamically balancing things? Like a setup that measures amplitude and phase of vibrations and then computes what amount of mass to remove and where.

[@ethanmiller5487]

You could make that a hands-free phone with a rubber band or sweatband like all the cool kids lol

[@111elf1]

is it possible that on version 1 one of the excentric 21gears was rotated 60° and thus the excenters are out of sync? (this sentence makes sense in my mind)

[@furmek]

seems like it! The internal 20 lobed - 6 holed parts have only one axis (plane?) os symmetry. If you rotate them by 60 degrees of what the supposed to be you will start pushing outer "race" out of shape.

[@Acamperfull]

Could you reduce the wobbling if you had three discs where disc 1 and 3 are in sync (same cam angle) with half the with of the middle disc which is running on cam opposite to the other cams. I think the cams wobble forces on the ring could balance each other this way? Very nice solution with the poor mans big bearing btw!

[@ethrilswifthawk3769]

i think in the first version one of the inner cams was a tooth off or something causing the output bolts to press them further out then the diameter of the housing, thus the flex

[@nicholasbackus492]

where do you get bearings that size? all of the ones i look at are super expensive

[@mastasolo]

How often do 3D printed parts get scrapped with your projects? if it's a lot, I think a fun project would be to try and reclaim some of it and make your own filament spools.

[@mhenlopotter1612]

Petition for James to buy a small 12V screwdriver 😂

[@ObserverChat]

What PWM controllers are used to control 3 phase BLDC forward and backword? thanks. these days i use stepper motors with gcode streamer. - I just love this channel.

[@RevUnstableBoy]

I think what was happening with the first design was the gear was out of proper timing between the holes for the output bearing and the gear teeth. much like having to put the gear halves together so that the holes and the gear teeth line up, they have to be timed inside the outer gear so that they mesh properly with the holes lining up properly.

[@Pgr-pt5ep]

The size of the 3D printed parts he makes scares my like a kid would when getting close to a steam locomotive.

[@42maneatingplants14]

I love that it's a compact gear reduction the size of a basketball.😂

[@eelcohoogendoorn8044]

Seems the first version may have been assembled at an offset? I think there is multiple almost-aligned ways of getting the discs in there; looks like that to me.

[@MrEthereal]

I always wonder if it's a struggle for you to get the tolerances correct between all the press-fitted parts, or if you usually get it first try nowadays.

[@Blue-bf8lv]

allowing the public to create their own customizable robo dogs is amazing.

[@Mikiek82bit]

I get flashbacks to Henry Winkler using the phone in The Waterboy in your last few videos.

[@SacredHeart0520]

This guy is like einstein but with engineering in modernday

[@Eddy_AREA99]

Hi James, huge fan here. Your content is always a source of inspiration, blending creativity with technical insight. It's clear the role sponsorships play in facilitating your projects, and while support is essential, the recent increase in sponsored segments seems to detract from the fluidity and engagement of your videos. Perhaps there's a middle ground where sponsorships can be integrated more naturally, without overshadowing the fantastic work you do. Maybe shorter sponsor messages or a dedicated spot that doesn't interrupt the project flow could help maintain the integrity of your content. Thanks for all the hard work you put into your channel. Your projects have been incredibly inspiring, and I look forward to seeing how you'll navigate this challenge. Keep up the great work!

[@freakinccdevilleiv380]

Awesome

[@corwin.macleod]

So you have an rv gearbox, a planetary gearbox already mounted on a motor and a belt transmittion on top of it. I think there is some room for optimisation here.

[@Psyconinja1532]

So are we safe to assume that the "much bigger project" is gonna be a ride-able open-dog?

[@filonin2]

Why are you holding a phone? Did your mic break?