What is Strain Wave Gear a.k.a. Harmonic Drive? A Perfect Gear Set For Robotics Applications!?

In this tutorial we will learn what is Strain Wave Gear, also known as Harmonic Drive.

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[igorradevski]

No words can be said to explain how your overall effort and metodology contribute to the world of engineering in a clear and precise way. You are the true example of a leader who add value to the things that surround him.
Engineering at its finest!

[michaelhawthorne]

That's a great bit of Things went together beautifully....really enjoyed watching that, thanks for uploading...

[Chris-bgmk]

If you attach a precision encoder or resolver to the input and output and graph the relationships you will find that harmonic drives have some weird nonlinearities. We were trying to use them for some very high precision robotics applications in the 90s and this gave us big headaches!

[robertamurrant]

That's amazing that you can make this with a 3d printer.
I'm in the middle of building my own 3d printer and will definitely try making this once I've learnt how my printer works

[qzorn]

this is one of the most innovative projects i have watched... 1st. the strain wave gear how did anyone ever think of it? 2nd. fantastic 3D printer project 3rd. great arduino project! thanks..:)

[klausnielsen]

"The shape came out decent in the end" That is the most humble understated desciption I've heard all month. Acrylic can be such a pain to work with and your part came out accurate and perfectly shaped even though your used hand tools. Well done on all counts. Really well done indeed. Keep it up :-)

[frsaund]

Really enjoyed this video, loved the commentary at 10:21

[StefsEngineering]

These strain wave gears make me smile, I'd love to use them but they are really expensive....

Nice printed model!

[ExtantFrodo]

Very well explained in a clear and and concise fashion (finally!). Thank you very much.
Did you notice that after you applied the tape (video mark 15:00 ) the outer housing was flexing quite a lot. This is a very interesting set up that allows better than worm gear ratios concentrically. Remarkable!

[its_crossfader]

After watching other videos, I found this one to be straight to the point and it gave me a clear-cut idea about harmonic drives. Thank you.

[ctoforhire]

This was an awesome descriptive walk through of a design element many could use in robotic applications!

[amargupta.]

Best explation ever. Great visualisation, can see the effort that was put in it.
But I have too many questions.

1. Can it be used as high torque lowspeed to low torque higher speeds? ( Just like normal gear box using in both the direction)

2. What if we use very high speed motors ( drone motors) as input?

3. Can flexible inner teeth made of aluminum withstand higher input rpm?

4. Efficiency and heating?

I have lot more to ask but just need these answers.

I know these are a bit weird questions, just want to compare with other models of gear boxes.

BTW you got a new subscriber...

All the best for future videos and lots of love from India.

[samosaarts]

That drive mechanism is absolutely genius! Love it, weirdly haven't heard about it before. Tickled my mechanical engineering itch so good...

[billkonkel]

Great video. I watch a few others on harmonic gearing, but this is the first one where the operation of the gears was quickly discernible, thanks!

[tgirard]

That was fantastic. I now understand both the basics of a Strain Wave Gear Drive as well as the inherent complexities of making a specific size drive with little to no backlash. No wonder they're so freaking expensive. Of course, I have to build this now. thanks so much for sharing !!

[Ucceah]

great work, instant subscription!
harmonic drives really are an ingeniously simple and elegant mechanism, and the form factor is just perfect for robotics. (wonder how slim you could make a hollow one) but i think for 3D printed projects requiring a lot reduction and torque, the money still is in worm gears and good old linear screw actuators.

[tdtrecordsmusic]

woa, this project has evolved !! I made one when it first popped up on thingiverse. 3-5 years ago... Excellent video. My 2c = I think the size of the inner teeth will need to be non standard. The size is based on the traditional gear formulas. Those are meant to mesh with each other and I think the backlash problem will be solved by customizing the tooth profile. For example: Making the inner tooth profile thicker near the root(pressure angle?) ... OR Why not think outside the box and use 2 sets of gears !! You know that old trick where the slack in 'linear rails' is removed by using a second rail which is offset. Split the rail and set the offset, So one rail is on one side of the tooth, and the other rail is pushed against the next. On small music players it was merely a spring which provided this tension. //// Also, I've been a fan of printing flat templates >> In the end, you made the acrylic face plate << Yea, so I've been intentionally making paper thin part templates in the 3D printer. It works really when you want a metal shape. U get the program to make a flat pattern / then print the flat with a flexible filament(petg works fine) / then fold your metal by hand tools / Yea the precision is insane cool. / Can also make bend helpers & reliefs to assist folding.

[PhilJonesIII]

Back in the early 80s we were working at a technical college and built a small robot-arm that was controlled by one of the early PCs.

We could get the arm to touch the same point maybe 5 times out of 10. No stepper motors were available to us back then.
Still, it was quite something and we were pleased with the result. A little frustrating to know we could have done so much better with a little more resource, a little more

And now this! Less than 40 years later and we can make components using 3d printers using software that was the stuff of dreams back then. (Actually, we had Autocad which was great for the time but so sloooow). Had you suggested that things like the Arduino would be available in the future, then few would have believed.

Your video is inspirational. Thank you for sharing.

[bonafide]

CraftWare slicer has the same parameter like the Horizontal Expansion, but it is called Vertical Shell Offset and I usually set it to 0.07mm for the best results.
Thank you for the nice video! Good explanation!

[modecharlie]

This type of gearing system would be perfect for an equatorial mount for a telescope. The backlash would have to be limited considerably though. Awesome video, thanks