Harmonic vs Cycloidal Drive - Torque, Backlash and Wear Test

День тому

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Parts list (check website article for full list, affiliate links):
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In this video we will find out what’s better, a 3D printed harmonic drive or a 3D printed cycloidal drive. Here I have these two gearboxes or speed reducers that I made which have the same size and reduction ration of 25:1. I will compare them in several categories, measure their efficiency or torque output, measure their accuracy or backlash, and see how durable they are.
I will explain how I designed and assembled both of them, and I will give you some useful tips and tricks for 3D printing them, show you what can go wrong and what can we improve to get them better, things that I have learnt along the way of making several of these.
Actually, this is my 4th video talking about these gearboxes, and why is so? Well, these gearboxes are good choice for robotics applications and in future videos I plan to make some robots that will employ this type of gearboxes.
00:00 What are Harmonic and Cycloidal Drives?
02:13 Designing
07:56 3D Printing
09:09 Assembling
15:02 Backlash Comparison
16:25 Torque Comparison
17:46 NEMA23 Torque
19:56 Verdict
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КОМЕНТАРІ: 339

@HowToMechatronics 6 місяців тому

Check out my favorite 3D printers, the K1 Max: amzn.to/3txQUC6 or if you are on a budget, the Ender-3 V3 SE: amzn.to/3FkCPus I hope you enjoyed this video and learned something new! For more content like this, please consider supporting me on Patreon: www.patreon.com/howtomechatronics P.S. If you are interested in the measuring tools: Force meter: amzn.to/3FEUAnS ; Digital dial indicator: amzn.to/3PDvSco

@Dazdigo Рік тому

You should throw a planetary gearbox in there as well and use it as a baseline.

@Dustmadeout Рік тому

Yes please.

@JM_Tushe Рік тому

It wouldn't be an easy comparison, a planetary gearbox would require to be bigger than these (if we also want 1:25) or have gears with way smaller teeth (a 3D printer would have problems with that).

@ihydf Рік тому

If the intended use is robotics, isn't planetary gearbox excluded on account backlash?

@strictnonconformist7369 Рік тому

@@ihydf that depends on the use-case: not all scenarios require much precision.

@HowToMechatronics Рік тому

Yep, I guess I should try a planetary gearbox as well.

@charetjc Рік тому

I tried to 3d print small S springs in PLA for a circuit probe and found the PLA would brittle fracture if left under strain over night, and otherwise lose flexibility eventually. I switched to PETG and have yet to break the S springs. Might give PETG a try for the flex spline. It's more sticky than molten PLA, but doesn't require a heated enclosure like ABS. Excellent video presentation. Bravo.

@victisomega4248 11 місяців тому

That outcome really shocked me, in terms of durability over time. When I first saw them both in operation, the cycloidal looked like it had more flex and strain on some parts. But thank you, I’m not sure why this showed up in my feed, but it did and I learned something!

@adamrowsell938 Рік тому

Dude you're killing it. I need to work with you or for you. I love the delivery and competence and clarity. Nice walk through the progress of logical thought. Ontop of the work you kindly made a video. Thank-you

@Designbyapro Рік тому

Now that you have created wonderful 3d printed prototypes to prove the concept, I'd love to see this taken to the next stage, and produce metal parts, either from CNC parts, or maybe testing out parts made from metal 3d printers. Great work on all this.

@HowToMechatronics Рік тому

That would be cool, but I need to make some CNC machines myself first. :)

@Eduardo_Espinoza Рік тому

I'm so glad metal 3d printers are becoming a thing now!:D

@laharl2k 4 місяці тому

@@HowToMechatronics you should be able to make the cycloidal gears out of aluminium with one of those cheap chinese 2040 CNCs. the parts are ideal for a cnc, just make sure to check the backlash as those machines are known to have some.

@philipthalmann9216 10 місяців тому

Hats off to you! That was a heck of a lot of work by the looks of it and a very thorough look into this topic. Well done! I've increased my understanding as well.

@jerryocrow1 Рік тому

Very impressive. It takes a lot of engineering education, training, experience and testing testing testing. Thank you.

@nigelhungerford-symes5059 Рік тому

For the Australian Rover Challenge I used a flexspline that was printed in solid TPU of 95A Shore hardness and it performed really well. This choice was landed on after a significant amount of testing.

@_..-.._..-.._ 2 місяці тому

TPU is amazing stuff.

@1003hafiz Рік тому

The amount of deep work to achieve this result is crazy respect

@EclipseAtDusk Рік тому

I’ll have to go watch that Cycloidal drive video after this one - I used to work in a factory that made cycloidal drive three phase motors, and I always wondered what was so special about the cycloidal drive

@rdyer8764 Рік тому

Been a subscriber for a long time. Your stuff gets more and more technically sophisticated. 👍👍

@HowToMechatronics Рік тому

Thank you! :)

@jonamr Рік тому

I think that you can increase the durability of the flex spline if you add a radius of 2 or 3 mm in the bottom of the cup around the wall.

@markogts Рік тому

I agree. Or also, build the ring without the bottom. Create a separate disc for bottom. Connect ring and bottom with "L" shaped brackets. In this way you can have different materials, plastic for the flexible toothed ring and metal for the torque transmission.

@Eduardo_Espinoza Рік тому

Agreed, it even has extra space for additional reinforcement:)

@lukearts2954 Рік тому

That, and using vertical slots would also greatly improve the longevity. It would also allow for a more shallow cup, reducing the lever and stresses at the corner.

@damienmartinguillerez Рік тому

For the flex spline, it is something that need to flex, so I would definitely go with TPU or Nylon, PLA is nice for prototyping and part that needs strength but not for flexibility. Anyway this is a really interesting test, I'd love to see it with a different material for the flex spline.

@HowToMechatronics Рік тому

Yep, thanks for the input! I should try different material as well as different design.

@RobertQuattlebaum Рік тому

Yep, Nylon would work great.

@Daniel-bu4gx Рік тому

I would try PTEG for the flex part. It's way more flexible than PLA but nearly as easy to print. I also worked with TPU and would guess that it is to soft for this application. But maybe some of the harder variants could be worth a try.

@andybrice2711 Рік тому

@@Daniel-bu4gx I reckon a TPU with Shore Hardness D60 or greater would be good for this. That's similar to a skateboard wheel. It would have excellent resistance to abrasion and creep. But yes, even a regular PETG would be vastly better than PLA in this application.

@mustafabhadsorawala9608 Рік тому

Adding a fillet at the fallow edge on the flex spline might also solve a lot of issues!

@lessspeech7129 9 місяців тому

Awesome, love your channel a lot

@paaabl0. 9 місяців тому

Wow, great video! One of the best dyi on this topic. Really awesome job! Thanks for sharing your experiences and very interesting comparative approach.

@mircon2198 Рік тому

Nice, and greetings from Germany. Best for 2023 :)

@Engineering4Life 11 місяців тому

Excellent work and great presentation!

@mattw7949 Рік тому

Excellent video. Thank you for doing these.

@MaxMustermann-sm4qu Рік тому

Thank you very much for this great video. Little Tipp: You could try to shrink the length of the teeth on the harmonic drive, so you don't need to stretch the material that much. Also it might be a good idea, to use 1 bigger bearing instead of 3 (or one) smaller ones, to stretch the pressure / load.

@barfboy2000 Місяць тому

with printing one could try a few things in geometry on the flex spline to reduce strain energy while mitigating loses in torque strength since your stuck with thick walls due to plastic. When you handle the metal harmonic drive splines it becomes clear that the thickness is very important. The way it necks down just outside the mounting flange is interesting, probably ground, and the teeth are way shallower than your model. They have a more stubby trapezoidal tooth profile. They also have pretty tight tols when it comes to housing alignment and offsets, getting a plastic printed one to work as proof of concept is pretty cool.

@willam5065 2 місяці тому

Good job. Creative use of bearings for wave generator instead of using sliding surfaces

@PhG1961 Рік тому

Really awesome ! Outstanding work !

@HowToMechatronics Рік тому

Thank you!

@ThomasEWalker Рік тому

Thanks for this comparison! Really interesting!

@HowToMechatronics Рік тому

Glad you liked it!

@tctn Рік тому

We are using harmonic gearbox with 80:1 ratio as a phase adjustment device between two or more rotary axes on printing presses. There are many different cases where these compact gearboxes are used for other than just speed reduction. You can cover those cases at some point of time. That would broaden your viewers perception of gearbox.

@DaveEtchells 9 місяців тому

It may be too much to explain in just a comment, but how does the harmonic gearbox work for phase adjustment between axes? It sounds like an interesting application that I’d never heard of before.

@_..-.._..-.._ 2 місяці тому

@@DaveEtchellsI would assume the stepper that drives the secondary print rollers is mounted on the harmonic drive or attached and spins forward or backward to change the phase. Just like automotive VVT technology that advances and retards the camshafts in relation to each other and the crankshaft, despite all being driven by the same chain. It’s used to optimize valve timing.

@user-sv7pp7qh6z Рік тому

넌 진짜 천재다.. 너무 고마워

@0102MOA 7 місяців тому

I believe it would be very interesting if you made a motor for an e-bike.

@LaserFur Рік тому

one thought on the flex drive is to take advantage of the 3D printing and make a series of bellows or waves in the plate and tube.

@ericgolub8589 Рік тому

Great video/channel, keep up the good work

@HowToMechatronics Рік тому

Thank you very much!

@andysPARK 11 місяців тому

Really good work, thanks

@julienlogeard Рік тому

Merci beaucoup mec, excellent taf !

@brandonb417 Рік тому

Hey all, just FYI, the equation as copied and pasted into SW had some issues. I copy and pasted it directly into SW2022 and it came up with something that looked more like a flower than a gear. After watching a video on Stepbystep-robotics channel I was able to figure it out. He had done some intermediate calcs on a couple of the terms and then replaced those terms in the equation and removed the associated parentheses that are no longer needed. This solved the problem. Also, in SW you can use the equation editor to lay out your terms and then put the equation into the sketch using the terms with, with " around each term. This makes your disk editable without having to re-copy/paste the equation in.

@PawelGrzelak Рік тому

This is just beautiful. Thank you.

@HowToMechatronics Рік тому

Glad you like it!

@pascaljean2333 7 місяців тому

What about a hybrid tpu/pla harmonic drive? Pla for shaft inserted into a tpu geared cup

@escain Рік тому

To be totally fair, the cycloidal drive has quite some metal parts, which the harmonic drive don't. Also, the size is optimized for the cycloidal drive, not for the harmonic drive. I suppose an harmonic drive with longer deformation, could even have smaller diameter and get better result. Also, the joint between the back and the side of the harmonic inner gear (the one breaking), could be reinforced in many ways.

@HowToMechatronics Рік тому

Yep, you are totally right.

@piconano Рік тому

I think they are both great if made of right types of steel, and not plastic. They are very compact and expensive, but zero backlash is what they are also known for.

@baorozzo Рік тому

I use them for work, they really have zero backlash. They also are efficient only on specific range of torque. If wrongly dimensioned for the work, they became inefficient really quickly.

@HowToMechatronics Рік тому

I believe that's right. Thanks for the input!

@IamusTheFox 7 місяців тому

I wonder if something like petg would do better for the harmonic drive?

@tapirath Рік тому

you could also try with an inverted timing belt. a hefty 8 mm pitch would work well I think in your case. I have a design with 3mm pitch and it works really well. durability would be quite good theoritically.

@HowToMechatronics Рік тому

Yeah, I believe that could work well. Thanks for the input!

@ArnaudMEURET Рік тому

The audience _is_ impressed. As usual here. 😊👍

@HowToMechatronics Рік тому

Glad to hear it, thank you! :)

@johnathonwalty8915 3 місяці тому

Very cool. What was the weight difference between the 2 drives?

@ADBBuild Рік тому

The Fanuc robots we have at work use all metal harmonic drives in their joints. I've always been fascinated with them since I first saw them there.

@TheBananaJoint Рік тому

May I ask which type are you using? I remember that the cycloidal gear is also commonly used in their R2000 series.

@fearapjr 3 місяці тому

The bigger the Fanuc robot, the more you'll see a Cycloidal@@TheBananaJoint

@spolkyc777 Рік тому

For the flex spline, what if you mad that separating it in to 3 types of parts. Back plate to couple in to the input, a ring gear for the output, and several "fingers" (basically cantilever springs) that go between the input plate and output gear. This would kinda look like a drawn out clutch pressure plate. The advantage is the printing direction could be down the axis of the flex spline. You could also curve in where it connects to the input plate, reducing the stress concentration and mix up the materials for each part. Great video and lots of fun!!

@spolkyc777 Рік тому

Or I guess you could get something like a 1/16" thick sheet of HDPE and wrap that in to a cylinder instead of printing the cantilever spring fingers. Either way thanks for sharing the projects!!

@Bianchi77 11 місяців тому

Nice video, thank you for sharing it :)

@temyraverdana6421 Рік тому

Thanks a lot for another wonderfull lesson and see you next

@HowToMechatronics Рік тому

My pleasure!

@holikarbon 7 місяців тому

Thank yok for STL files.

@gppl77 Рік тому

There are quite wide 3GT closed belts, like 20-25 mm width, with various lengths. You could glue one side to output shaft and use another as running track for wave generator. With PLA the glued side will still be the weakest point - the belt under load might just rip out PLA it's glued to. So the next sorta improvement would be to glue the belt not to a 3d printed part, but to an aluminium disk of appropriate diameter and thickness about 3mm. With an epoxy and proper surface preparation it should be quite strong. It'd be very interesting to see how much load it can survive:)

@simplygenius4847 Рік тому

Wow, learned so much

@user-zh2ws2qh5f Рік тому

Cool reductors!

@DIYGuitarMods Місяць тому

I've 3d printed several strain wave gears of a very similar design. I got the backlash quite low but had the same delamination problems with the flexible geared part and put the project aside for now. I'd love to try your cycloidal design!

@HowToMechatronics Місяць тому

They are so cool be hard to get them functional with 3D printing. I also should give it few more tries, printing them with a bit different design and also with other materials like Nylon or ASA maybe. Cheers!

@DIYGuitarMods Місяць тому

Yes! I bet a good option would be to have that part MJF printed in nylon12 by like JLCPCB or Xometry. Also, the reason I wanted to build the strain wave gear in the first place was to make a DSLR camera tilt and pivot set up. This is such an awesome choice for that if the backlash can be improved @@HowToMechatronics

@dylanpendlebury23 Рік тому

the teeth on your flex spline are pretty big. You can probably get them down to MOD 0.8 which will reduce the amount of deflection the flex spline will need to undergo AND increase the gear ratio per the same gearbox diameter. Also, try making a elliptical bearing with BBs like the youtube ZeroBacklash does with his strainwave drive gearbox.

@HowToMechatronics Рік тому

Thanks for the input! Yeah, a smaller gear module would help as we would need less deflection of the flex spline. Though I'm not sure how low we could and get a accurate one with the 3D printers. We can definitely achieve better results with improving the design.

@DaveEtchells 9 місяців тому

I was surprised to see that much backlash in the harmonic drive; commercial metal ones are zero-backlash. Looking at the video, it seems like the flex spline teeth could be a little bigger without binding, that’d probably reduce the backlash a good bit. I still wouldn’t expect it to be as strong as the cycloidal mechanism, but a tighter-fitting nylon spline should be both more durable and lower backlash. (Nylon is also “slippery-er” than PLA, so might be more efficient.) Great series, BTW!

@NabtescoMotionControl 3 місяці тому

Backlash is defined differently by different gearbox manufacturers.

@zrebbesh Рік тому

Test the harmonic planetary drive! I think it's better than both. It's a harmonic drive that can be made with completely rigid parts. Two ring gears of the same diameter with tooth counts differing by one, one of them fixed and the other connected to output. A rotating input carrying (at least) three spur gears around in contact with both ring gears. Two of the three spur gears have teeth out of phase by one-third of a tooth, but all have the same number of teeth in contact with both rings. Reduction ratio is equal to the tooth count of the output ring.

@DaveEtchells 9 місяців тому

This sounds *really* interesting!

@_..-.._..-.._ 2 місяці тому

Wow, amazing idea.

@jonathanp___________3606 Рік тому

I think you could shorten the length of the flex spline gearbox by adding flexibility to the flex spline walls and shortening the flex spline. If you removed material from the thin wall of the flex spline in an n-tuple helical pattern, it would allow greater displacement of the side of the spline with the teeth. It’s possible removing material would cause too much increase in stress concentrations though.

@de-bodgery Рік тому

I think even if you made the flex drive from thin spring steel for maximum flexibility and decent durability, You'd still break them! You can't have parts flexing all the time without it stressing them in some way. Probably with spring steel, you'd stress the areas between the teeth. Something that will probably improve durability, but will increase back lash is to have the flex ring float in dove tail slots in the back plate. This will let them move independently of each other a little bit. The flexible section will have to NOT be constrained from flexing anywhere so that there are no high stress zones.

@maciejpospiech4371 Рік тому

You probably do not need any "Expansion" setting, they are not needed to get dimensionally good prints. Most important setting is (if you're using Cura, I don't know in other software) the "Slicing tolerance" set to "Exclusive". I was struggling like you with prints until I changed "Slicing tolerance" setting from "Middle" to "Exclusive" end now every print is perfect to the 0.05 I would say (I tested some clearances changing by 0.05, and you could tell that there was change). You can find this setting in "Experimental" section in Cura. Even 3D printed threads right from the Fusion 360 are working righty away without any change in clearances. This "Horizontal expansion" setting, as many other settings, was created when 3D printing was at its beginnings. People back then tried to solve problems in not always to say the best ways. And now these settings still are there, but they are not really have to be used nowadays. There was a video explaining that phenomenon on UKposts but unfortunately I Forgot channel and name guy who made it. Maybe someone reading that can comment below the link. EDIT: Of course for this to work printer have to be calibrated (e-steps)

@justaguycalledjosh 11 місяців тому

For future harmonics, i'd try making the flex out of two parts, a rigid backplate and a more flexible ring, perhaps TPU?

@smithtorreysmith Рік тому

Awesome video. Thanks!!

@HowToMechatronics Рік тому

Thanks!

@newgreen956 Рік тому

You can reduce the backlash of the cycloidal drive by offsetting the two eccentricities by a couple of degrees.

@Leroys_Stuff Рік тому

This was a great test build break repeat

@JM_Tushe Рік тому

Thanks for the video! I think I still stick with the harmonic drive because of the reduced backlash but I can't deny the durability of the cycloidal drive is very appealing. 👍

@HowToMechatronics Рік тому

Fair enough! :)

@tortenschiebermitsenf9282 Рік тому

They have no backlash. If they do, they are broke

@jawawookie Рік тому

Would there be a hobby accessable way to cast the flex spline? Or spin one out of thin metal sheet?

@mehmetumut2163 7 місяців тому

weight? (harmonic gear box 3d and cnc)

@ErosNicolau Рік тому

If you plan on properly (and by that I mean more thoroughly) testing the harmonic drive principle you might take a look at the less known double rigid external gear config (one with 50 and one with 48 teeth, exactly as many as the belt flex spline). For the same compactness of the design you're getting a much higher torque...

@samuelkleiner6143 Рік тому

Any links for this? I can't seem to google it

@ErosNicolau Рік тому

@@samuelkleiner6143 I posted a link twice already, my replies keep vanishing. Just look for "FR pancake gear" and you'll see it

@HowToMechatronics Рік тому

Hey, thanks for the input. Yes, that kind of setup could work better and we could get better results with materials like this.

@ErosNicolau Рік тому

@@HowToMechatronics i know, I built a full metal one myself. Seeing your video makes me wanna build a 3d printed pancake one myself just for shits and giggles 🤭

@_..-.._..-.._ 2 місяці тому

@@ErosNicolauSo you suggest something, the person says “that’s a great idea” and you basically say “duh, that’s why I said it” new project: social skills.

@RoboticsNerd 27 днів тому

For robots, mass is critical. Torque Density would have been nice to compare too. But fantastic work!

@SimonSozzi7258 Рік тому

I never saw that deforming gear ⚙ version. That's so clever. That's not how the metal version you show works, no? I mean, the end result is the same but achieved by a different mechanism. Seems so simple. (Wave generator! I love it.)

@Akideoni Рік тому

The flex gear for the harmonic drive could be replaced with a vulcanized rubber timing belt for better reliability. As for it's operating limits it did be interesting to find out. But from an operation and maintenance stand point I could see people might go with harmonic drive due to the reduced need to troubleshoot point of failure. As the common saying goes on the shop floor "the more the parts the more points it would fail"

@josepheirman4987 5 місяців тому

harmonic gearboxes usually have a flexible bearing as the wave generator, it leads to smoother operation. you are right that the flex spline is the weak link. but that's a failure of the material. I've seen metal ones where the teeth ripped off the flex spline before the wall of the flex spline failed.

@Kumurajiva Рік тому

fabulous

@shashikantsingh6555 Рік тому

Hello Dejan, i really like the quality of your 3d printer.. could you please tell me which 3d printer you use?

@quinnobi42 Рік тому

I would recommend trying to print the flex spline in PETG, which is more flexible than PLA and just about as easy to print.

@HowToMechatronics Рік тому

Yep, it would be better for sure.

@conorstewart2214 Рік тому

Trying different materials would be a good next step, like more flexible materials for the flex spline. Nylon might be a good choice, it is quite flexible whilst being very tough and having very good layer adhesion, it is also low friction.

@mrebholz Рік тому

Also using the 3d-parts as positives for mold building to test more materials that cannot be printed easily but manufactured with molds.

@DaniGirl6 Рік тому

Great video! Looks like that was a lot of work. I'm surprised PLA performed that well. I'm curious how much of a difference switching to PETG would make. Would the extra elasticity help the harmonic drive enough to make a measurable difference in reliability and performance? How much of a difference? Also would that elasticity hinder the cycloidal drive max force?

@HowToMechatronics Рік тому

Thank you! Yeah, I would like to know what difference PETG would make, but I didn't have the chance to test it this time. I will try to make some tests with different materials in a future video. Cheers!

@Arduino.bibassata Рік тому

Good idea

@Aldrenean 11 місяців тому

Is the play explained by the imperfect fit of the metal pins in their bushings?

@calebr4961 Рік тому

98A TPU might work well for the flex spline of the harmonic drive.

@electric_boogaloo496 Рік тому

Regarding the cycloidal drive, I was wondering if a much durable version can be made with bicycle components. Rollers in the chain wil act as the rollers, the sprocket with act as the cycloidal disc.

@danielsaenz5570 Рік тому

Wow, very interesting stuff in this video! Your content is superb! Since you're a mechatronics engineer, you took both Mechanical and electrical engineering. Driving motors is considered what? Mechanical or electrical? Thanks a lot!!

@simonjeppesen9484 Рік тому

Great video, but the tooth profile of a strain wave gear is different from the tooth profile of spur gears.

@Naxt366 Рік тому

please do a second comparison run on both 25percent bigger gearboxes!

@chriscockrell9495 5 місяців тому

Solid works for makers

@theofficialczex1708 Рік тому

PETG is a much better choice for flex splines. It isn't as strong as PLA but is more durable, flexible, and better at elastic deformation.

@PoldLp Рік тому

I would be interested to know how much the cyloidal drive with 3d printed pins would withstand

@johnlocke9609 5 місяців тому

Hello friend, use a closed timing belt htd8m as a flexible part, you'll get long durability also the outside part could be another timing belt just inside out to the rigid part.

@geppetto3244 Рік тому

Hello, taulman Bridge Nylon will be your best friend for the harmonic drive ...

@prdoyle 5 місяців тому

Could the flex spline cup curve in at the bottom, rather than have a sharp 90 degree joint? Would that make it less likely to break there?

@mikeboudreaux2964 Рік тому

What was the mass difference between the two actuators? Seems like the steel pins in the cycloidal would make the mass of the cycloidal much higher.

@jakeiven1985 Рік тому

I’d be curious I saw a video about rv reducers hi would that compare having more surface to carry the stress

@j0hn7r0n Рік тому

What would be a good material for the flex spline? PETG? Some composite?

@Robonza Рік тому

Great video. It would be interesting to see how good a cycloidal would be with laser cut parts which will be much stronger

@kearneylackas Рік тому

Or even just using 100% infill. The cycloidal tooth probably would not have collapsed if there weren't voids in the there.

@HowToMechatronics Рік тому

Thanks! Yeah, it would be interesting to see that.

@jesseservice7828 Рік тому

Muito bom !

@alpgenrobotics Рік тому

perfect 🤩

@HowToMechatronics Рік тому

Thank you! 😀

@greggv8 Рік тому

A more durable way to build a 3D printed harmonic drive is instead of printing the flex spline cup, invert a cogged belt. Print an internally toothed ring with a plug or plate or a groove inside into which one edge of the belt will fit. The part the belt goes into has the same diameter and number of teeth as the belt. There's a cup with a rigid connection to drive and bearings, with a supremely flexible spline that is not going to fatigue and break along layer lines.

@konradkisiel2067 Рік тому

I think that some filet or chamfer on the area where the break in harmonic drive occurs would be a good improvement. Also, PLA is not suitable for parts which are under constant deformation, probably PET-G, nylon or ABS would be better for this application. Thank you for interesting content.

@HowToMechatronics Рік тому

Thank you!

@thebloxxer22 Рік тому

Instead of PLA, wouldn't TPU be a better choice for the Harmonic Flexible Gear? Do a comparison between the two please.

@xTreme.Power. Рік тому

Hello, why you not simply print the deformable part of the Harmonic drive in hard TPU ? ( D58 shore) I use it in some customers project where they need flexibility and hardness. It can deform completely and never break at all

@woutervossebeld4664 Місяць тому

put a chamfer in the harmonic drive flex spline where the wall meets the bottom side. That's a general 3d printing 'rule'.

@locknload517 Рік тому

better than any colege study in Brasil.

@dzidmail 10 місяців тому

What would you say is a minimum gear ratio with any of these gearboxes? I am currently using metal 5:1 planetary. I doubt I could achieve reasonable backdrivibility with these, because of large ratios.

@BigJoePotato Рік тому

Happy holidays 🎄 dan.

@HowToMechatronics Рік тому

Happy holidays!

@telelaci2 7 місяців тому

In the real life the Harmonic Drive is made from special alloy steel, the strength of the flex spline is not a problem at all. The number of teeth is much-much higher on both circular spline and flex spline so the backlash is really zero, at least unmeasurable. That makes it perfect choice for robotics, where the zero backlash is fundamental. Although the Cycloidal Drive's backlash is also very low, this gives an advantage to HD. Another problem you didn't meet, that is the vibration. You know the real machines may rotate at much higher revolution and that might add vibrations to the Cycloidal Drive due to it's eccentric nature. That can be a serious problem, vibrations kill machines in long term. Your 3D printed elements are not strong, not heat-resistant, dimensionally not accurate things, very hard to make good power transmission and driving elements with these properties.