Mini Harmonic Drive Teardown

In this video, a miniature harmonic drive is torn down. The drive was an older Vexta stepper/harmonic drive, with an attached closed-loop optical encoder.
For those who would like to support my projects, here is my Patreon Page: / brendaem
More information on harmonic drives:
en.wikipedia.org/wiki/Harmoni...
A quick look at photo-interrupters:
• A Quick Look at Photo ...
Kuka Industrial Robots, as mentioned:
www.kuka.com/en-us
Vexta:
www.orientalmotor.com/

[@sato4kaiba]

The screw for the optical encoder wheel was glued in with some type of fast acting glue (aka crazy glue). You were to use some acetone on it first.

[@teslastellar]

Thank you for the disassembly and the explanation 👍

[@haenselundgretel654]

Nice disassembly! Cheers mate for showing us this great motor!

[@joeteejoetee]

Yet another great video!

[@visualchallenge2413]

Nice Intro and texture of the table. An instructive video also. I don't grasp entirely how this motor works but I see the principle and I will search more.

[@franktkalcevic5342]

I had the same problem disassembling one of those that had a brushed motor. The brushed motor had the commutators worn down to nothing. I couldn't get the encoder wheel off the shaft, so sadly I couldn't recycle it.

[@gordon6029]

Very sad to watch but educational. Really nicely built. Thank you.

[@BrendaEM]

It may indeed live at the end of a 2-phase stepper.

[@mrsaizo0000]

It looks like a very accurate stepper motor..

[@BrendaEM]

Well, it has a stepper built into it. For me, the gearing is cool.

[@hisuiibmpower4]

wow this video is wonderful!thanks for showing the inner working of those sophisticated engineering marvels I've an important question and no where to ask,plz help! Since I'm trying to build a syringe pump,I'm looking for geared nema17 like stepper(without much success),I accidentally stumbled upon oridental motor's product most with reduction gears are five phase require their own driver.In this video u claimed u can turn the motor on(I suppose u have their driver).I've read some driver's manual it claimed driver accept pmw signal,can I use microcontroller such as arduion as pmw source to dive those motor? those motor sets are not cheap to try even second hand,plz help,thanks

[@BrendaEM]

Yes, and Arduino will drive a Vexta controller, though, the Vexta 5-phase controllers from this era have a Stepforward-pin and a Stepbackward-pin instead of the conventional Step / Direction. Also, these motors, marvels they may be are getting old for anything medical-related, research perhaps, but you would not want to make something like an insulin pump from them. I actually found that one brand of optocouplers in the drivers generally do not work for the sleep/wake, perhaps because of age.

[@canadianavenger]

Great teardown! It is a shame it was destroyed in the process... but a worthy sacrifice for science! :) As for the encoder the one thing you missed is that on the LED side there are two rows of slots, and they are 90degrees out of phase with each other. When coupled with the receivers, this results in a quadrature encoding where only one output phase switches at a time. If you would have laid a section of the disk over a bit of the plate you would see how the interference pattern moves,

[@BrendaEM]

You are right. It was a missed opportunity. Thanks for contributing. Mechanically, I think the drive will live.

[@besenyeim]

The interference pattern is also called Moiré pattern, if anyone is interested.

[@tttuberc]

Great to see what inside of that motor and gear box and thanks for the explanation of how it works. I'm surprised to see it doesn't take much force to spin the rotor while the cam is still in the "flexible cup" gear mechanism. How hard is it to squeeze or bend the cup a little? Thanks

[@BrendaEM]

The cup strained gear part is about as thick as 2 or 3 single edged razor blades at its thinnest part . It is flexible, but not too much.

[@tttuberc]

@@BrendaEM Thank you for your reply

[@Ucceah]

if you really want to get it to work again, you can either re-wind the existing motor, or get a nema16 or so, with a long shaft, and slap it on instead. on the motor side, acrulic or a 3D printed part as a mounting plate for another motor will be fine

[@BrendaEM]

I have the bag of parts for a NEMA 16.

[@TheRainHarvester]

12:38 why isn't it only rotating the cup?

[@BrendaEM]

In this case the oval bearing race that deforms the cup, has less friction than the main shaft bearings. It might have something to do with the amount of grease in each. In places I hold the cup with the edge of my finger, if that is what you are wondering about.

[@ameliabuns4058]

Awesome :o how expensive are these?

[@BrendaEM]

I am not sure. I should guess that the motor alone would have been over $500, perhaps $1200 with driver.

[@chicoxiba]

cool as

[@lukahutinski9075]

There is no magic in here. Its just a LED. I mean... its just 2 wires 😑😡?? UNsubscribed

[@BrendaEM]

I am sorry. I tried. The "magic" was that the encoder was 500 steps/rev, which is more than twice the resolution than the average 200 step motor, that and it was attached to a 50:1 or 100:1 to one harmonic drive system.