Wave Drive with Rolling Elements - Cycloidal Gear Alternative!

[@TastySlowCooker]

People in my life think I’m really smart but the truth is I just coast on content by people like you

[@ZappyOh]

This guy didn't invent this drive ... We all stand on the shoulders of giants.

[@TomWilbourn]

i have never read a comment on youtube that called me out like this one did! LOL

[@TomWilbourn]

@@ZappyOh he never said this guy invented the wave drive? He was referring to the printable/parametric files that this guy made.

[@MishinMachine]

Community and open source are very inspiring. It encourages sharing and coming up with new ideas

[@Luigi-q4q]

This is amazing :)! I stopped building cycloidal gears, because of the many bearings, rollers and less stability.. and this type of cyclo is solving all these problems :)

[@ErosNicolau]

You're the first guy Isee measuring backlash with that pointer on a wall, after me, many years ago :D (I used to do it at 10-12m distance, for greater acuracy) Careful: at 8:35, going one way, returning, then going that same way and returning you're not measuring backlash, but repeatability. To measure backlash you need to go one direction, return to zero, mark the position, then go the opposite direction and then back to zero, mark the new position and measure the difference. You might also want to measure the same under a relevant load. You will find backlash increasing with the load. That's called torsional rigidity and the smaller is the better. With plastic I imagine quite a load of it. On my Aluminium + Steel pancake system I was measuring 0.75 arcminutes under zero load (like you measured here) but 10 arcminutes extra per every Nm of torque added. Anyway, amazing work, especially explaining it and creating the parametric model!! That's awesome!

[@MishinMachine]

Thanks for the useful info! I've never tested backlash and torque before. Next time, I'll pay more attention to this.

[@cooperised]

I think the backlash measurement was when he attempted to manipulate the actuator by hand. It would require a lot of care to automate a backlash test because any asymmetric load is likely to take up the backlash (e.g. the action of gravity on the mass of the laser pointer in this setup).

[@ErosNicolau]

@@cooperised He's using a laser to measure, which is clear evidence he's perfectly aware that any external load can have in impact on the measurement, and that measuring at a distance is orders of magnitude more precise than the test people usually do (wiggle it like there't no tomorrow and concluding there's no backlash based on the perceived stiffness). So I don't think he was trying to Measure backlash when attempting to manipulate the actuator by hand, just to Assess if there's a gross amount thereof. Also, the laser pen is so light that the friction forces inside the unit are overcoming any imbalance the pen might induce, so that's negligible. Ask me how I know :D

[@tommyliao5508]

Been looking for something like this for a while now. Adjusting my backlash + torsional rigidity metrology systems now based on this, thank you!

[@evren.builds]

This is pretty amazing, first time seeing such a design. Thanks for sharing the model as well ❤

[@gotbread2]

The fact that you not only made one model, but a fully parametric one to generate all variations, is impressive! and really useful!

[@ThisIsToolman]

I can’t even begin to say how impressed I am!

[@swannschilling474]

This is great!!! Also the script is such an awesome addon!! What a gem!! I will definetely try this!! Thanks a lot!! 😊

[@critical_always]

Nice work! This is what the internet and 3D printing is for. Quickly try things and not immediately running to a patent office.

[@theavaliengineer]

I believe this is called an Abacus Drive - I've seen this sort of design talked about in papers, but never implemented by a hobbyist. Nice work!

[@MishinMachine]

Now I know about the Abacus Drive, thank you so much! As I understand it, it's a bit different: it uses a second cycloidal wheel on the wave generator instead of a round wheel.

[@theavaliengineer]

@@MishinMachine Interesting! It would be cool to see a comparison between the two devices, including full characterizations of the drives. This solution seems a lot easier to build, so I might incorporate it into some of my projects!

[@klausnielsen1537]

Great demo and how to. Really love that you also made your models available 👍 That's a beautiful move 😁Thank you.

[@rs4race]

I found this video a week ago and after deriving the equations for the wave profile, I realized I could just sweep the bearing cross section along the bearing path (cycloid). I got caught up yesterday with the bearing cage, but after watching your video I realize the bearings are allowed to move radially and shift angular pattern. This is pretty interesting, it makes me wonder if there will be any skidding that could be bad for wear and efficiency.

[@danh9002]

Great video! Thank you for sharing!

[@iopfarmer]

Great model! Thanks. I didn't know this type of drive existed 😊

[@curiosity-creates]

This is great! It would be very interesting to see the actual load carrying capacity and the efficiency of these drives. Thank you for the great video.

[@mehmetgul8686]

it is so amazing, thanks for sharing; it is what I need, there are so many cycloidal gear videos but yours is the best explained. thanks again, sir

[@surajjaiswal1371]

2:21 That ball drop sounds so satisfying!!!

[@RoboCNCnl]

Love this idea ! thanks for sharing

[@ahmedwaly9073]

Amazing gear drive ❤

[@Jorgefer88]

Very interesting your approach to a cycloidal gear! It makes me think about future designs, thanks! Quality content!

[@MishinMachine]

@@Jorgefer88 thank you!

[@stefanguiton]

Excellent work!

[@JesseSchoch]

I found and made a tooth type called the heliocentric gear that was fun to play with. I also made a ball reducer which also works with balls but uses tracks that are more like thrust bearings (not axial) thanks for sharing your design, i'll have to give this a try.

[@jamesmcgrene1379]

Awesome. Been looking for a more compact alternative to cycloidals for miniature robotics.

[@chuongnguyen4980]

Excellent design. Thank you for sharing. I will try it

[@MethoughtMagrathean]

Great work! Looking forward to new videos!

[@MishinMachine]

Thanks!

[@leogray1091]

This is a really really cool design! I love it ! The only thing I'm wondering is what about using mini ball bearings for the rollers? I can see that the roller cage is one point where it's sliding friction. It's probablly not bad, but seems less optimal. It is certainly not an option for small gearbox, but maybe an option for large gearbox?

[@MishinMachine]

This is a good idea! It should improve efficiency and precision, it can also solve the problem of a weak separator.

[@leogray1091]

@@MishinMachine Actually looking again at the video, I'm not sure how would you use the ball bearing as roller. I just realize the separator is not moving in the ecentric motion, which mean the bearing needs to go in and out on the seperator.

[@MishinMachine]

The separator's thickness is greater than the eccentricity, so the ball's center remains within the separator at all times.

[@bano99]

Awesome work, thank you for sharing this, you just got a new subscriber!

[@aldrickpeter]

I am looking for a reduction mechanism for my final year project. Imma implement this

[@Jim_One-wl4ke]

Awesome 👏, thanks for sharing.❤

[@CamdenWallraff]

Giving this one a whirl for sure - attempting to make a 6mm OD gearbox for some coreless motors with it

[@ellafoxoo]

Nice. Feeling a bit inspired to take this one step further, and make a compact 3D printer extruder now

[@MishinMachine]

@@ellafoxoo that would be awesome!

[@snapo1750]

this is so cool thanks

[@DaveEtchells]

What a great design, and an excellent vid explaining it! Thanks for the model too! The backlash seems quite good as it is, but I wonder if it could be even further improved by introducing a slight offset between two phases? That could make assembly difficult, but it might not be too bad if you assembled the two phases separately and then applied some torque as you were screwing the two parts together. This would increase friction and thus cost efficiency, but that might be fine in applications where zero backlash was important. With two sections 180 degrees out of phase with each other, is the rotation completely smooth or is there still some input/output nonlinearity?

[@MishinMachine]

Thank you! I don't quite understand how to offset the phases. But you can, for example, increase the size of the wave generator wheel a little and use precision hardened steel shafts as intermediate rollers. In my test I used nylon standoff spacers and a tiny offset in separator holes because my old 3d printer is not quite precise. Actually I haven't tested 180 degrees out of phase setup yet. Got carried away by another variant of this drive where this balancing issue should be resolved.

[@NathanDavidDodd]

@@MishinMachine The slight offset I think he is referring to is; instead of 180degrees, make it 179degrees for example. On the second phase. This intentional angle offset is used for involute gears now for the same result. Because the phase will be "misaligned" by 1 degree in this case, the tooth will likely collide, hence "no backlash". But they only work well with relatively light loads and present other eccentric output speed problems. (unless you rotate the Cycloid profile as well by 1 degree, but that eliminates the offsets purpose). Which is usually a deal breaker. Realistically even if you try for perfect 180degrees offset between crank lobes, you wont get it. So the natural tolerances do this for you in a way.

[@evanlane1690]

That's awesome! Do you need to stack two stages similar to cycloidal to avoid vibration? Edit: never mind. I just got to that part in the video. Great content!

[@dainazinas]

Nice vid. How do you get to the parameters tab @9:11?

[@MishinMachine]

Thanks! You need to double click on the "Roller Wave Gear 1" feature in the left sidebar.

[@M0darn]

Nice video! It's great that you're including some testing too. ( I agree with the other commenter saying that for backlash you should approach from different directions) Have you seen @LeviJanssen 's video of a co-planar compound cycloidal gear? "The Compound Cycloidal Drive - Something Novel" would love to see you make a video exploring this idea.

[@i-make-robots]

Cool. Got a torque load test?

[@MishinMachine]

I tried to test the load, but I haven't done it before and only had laggy Ikea scales. The results also really depend on the current of the motor driver. In my tests, the highest load was 1.4 kg on a 20 cm lever for a 20:1 reducer.

[@evren.builds]

@@MishinMachine was that with a nema17 stepper as well?

[@evren.builds]

@@MishinMachine So around 28kg*cm or 2.8Nm? holding torque and active torque can be a bit different but if we say nema17's are around 0.2-0.3Nm So its somewhere between 50-70%efficient? Would love to see more tests ^^

[@MishinMachine]

@@evren.builds yes

[@MishinMachine]

@@evren.builds I need to learn more about how to do these tests properly, and maybe I'll make a video about it in the future.

[@rupantaradhikary6580]

I am really interested in the small reducer it's look really nice and compact

[@김동길-q7y]

Hi, Thank you so much for sharing your work! I am trying to make my own version using parametric design that you provide but, I am wondering how can I do in 00:01:58 this ways?

[@MishinMachine]

Hi! You can just flip the separator, and you might need to put some bearing between the separator and the input(motor) shaft

[@김동길-q7y]

​@MishinMachine Thanks for the comment! Sorry, what i meant was 01:49 ways in on shpe! It was a bit tricky to set up a parameter

[@MishinMachine]

@@김동길-q7y Sorry, not quite sure what you mean. If you mean using the bearing surface for the wave generator, you just need to specify a suitable bearing diameter that is larger than the required size of the wave generator for your parameters. If you want to get an open gearbox setup as shown in the video, you can 3D print all the parts of this model without an output shaft and its bearing housing, and just flip the separator to face the motor mount during assembly. You can also modify the separator slightly to integrate a bearing on the motor shaft.

[@billyzelsnack]

Awesome!

[@moses5407]

Thanks for the great work and the fantastic parametric generator! How was the backdrivability of the 64:1 drive?

[@MishinMachine]

Thank you! It was hard to turn 😅I think the two-stage setup has low efficiency, I haven't measured it though.

[@叶青云]

Can you share the reducer suitable for the 42-step motor in the video? It seems that the onshape software cannot modify the reducer into a square one. Thank you very much!

[@MishinMachine]

I've added a link to the Nema 17 housing on my Urals page in description

[@evren.builds]

Do you think it would be possible to section out some precision ground shafts as an alternative to the rollers?

[@MishinMachine]

Yes, I tested them. It was my second option after the brass round standoffs shown at 2:39. You can try different options as long as they are round 😄. The model allows changing the diameter and height of the rollers.

[@limejournal8220]

What would you think about replacing the rollers with small bearings like MR62ZZ? I know it would be more expensive, but do you think that would have a significant performance gain?

[@MishinMachine]

Why not. But in this case you also need to use output pins setup like in cycloidal gears instead of a separator. The diameter of these pins should be less than the inner bearing diameter by the amount of eccentricity. So with MR62ZZ bearings and 1mm eccentricity, the pins should be 1mm in diameter.

[@contomo5710]

wait what, you can use the outer surface of the bearing? to me that blows my mind, because up until that point my brain was still working in strain wave gearbox space!

[@anatolyshkerin3569]

Amazing! What is this interesting electric screwdriver?

[@MishinMachine]

Thanks! It is Xiaomi Electric Precision Screwdriver.

[@titter3648]

Do you have a patent number or any other information on this gearing?

[@dekutree64]

Interesting design! But since the rollers have to move radially to follow the squiggle, I don't think there's any way for them to push tangentially on the output carrier without sliding friction. That will probably be your ultimate torque limiter. I wonder how it compares to a cycloidal of equal size.

[@MishinMachine]

Good point

[@Jean-yj9xq]

Hi, I am really interested in your reducer and I use solidworks, could you please send me the parametric equations to try to create one? thanks

[@MishinMachine]

Hi! I've added a github link to a python script on my page, please check.

[@tambunico4282]

hey i wonder if you have the nema 17 2 stages model on onshape, maybe I'm dumb but cant find it.

[@MishinMachine]

I've added a link to my Urals page, please check the description

[@tambunico4282]

@@MishinMachine thanks!

[@luke.perkin.online]

Did you do a torque test?

[@MishinMachine]

I'm learning about how to do these tests properly, and maybe I'll put it in the future videos.

[@МаксимВолокитин-о3х]

Очень круто 👍

[@MishinMachine]

@@МаксимВолокитин-о3х спасибо!

[@saeedshahriyari3398]

how can I have the STL files?

[@MishinMachine]

Please check the links in the description. You can generate your drive with parameters and export to STL

[@saeedshahriyari3398]

@@MishinMachine I dont have knowledge about design and Im not familiar with onshape :(

[@BarioIDL]

max torque: the strength of layer adhesion

[@SergeyToroshchin]

Екатеринбург =)))

[@MishinMachine]

Екатик 🫶

[@SergeyToroshchin]

@@MishinMachine 1) Можно попробовать побороть вибрацию путем балансировки эксцентрика ... я тяжёлой части "насверлить" дыр 2) Не думал собрать серву на базе BLDC мотора? собрать робо руку которая бы худо бедно могла в теории пару десятков КГ тягать

[@WINNPLAYER]

I found a similar gearbox in which the direction of rotation of the output shaft is discussed, depending on the number of rolling elements in the gearbox: kzbin.info/www/bejne/npebp5tumspsnsUsi=duANiOU8uvaQRpdP I checked, and indeed, if the number of rollers is one more than the number of arc-shaped grooves on the working profile, such a kinematic dependency is created where the output shaft rotates in the same direction as the eccentric. The synchronization of the direction of rotation of the eccentric with the output shaft is interesting, as well as the possibility of increasing the number of rollers by one more than the number of arc-shaped grooves to ensure their displacement on the other side of the groove crest. Could you make such a version of the gearbox? Thank you!