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gouldpa

Anti-backlash Cycloidal Gearbox

by gouldpa Apr 27, 2019
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Great Project, thanks!

About the encoder:

a) Which encoder did you use?
b) What do you mean by "encoder bearing holder" ? Is that a part of the encoder itself?
c) Is the screw to tap the encoder bearing holder (M3x0.5) M3X5mm?

Thanks!

Hi davbar
a) I use the AS5147 encoder
b) "encoder bearing holder" holds the bearing on the encoder side (opposite to motor side) of the housing
c) yes M3x05

What meterial should I use? Is PLA an option?

I use ABS but Nylon will be better. As the motor gets hot, PLA might not be best material. For initial testing and research any material would be fine.

I have another question, you have any suggestion on how to connect a 4mm shaft motor? (335KV: https://www.aliexpress.com/item/32908188142.html?spm=a2g0s.9042311.0.0.2ba34c4dES5rOo)

I would replace the shaft with a longer one.I use silver steel rod. Then drill a 1.5mm hole though the eccentric cam and the motor shaft and put in a 1.5mm pin.
https://hackaday.io/project/157812-3d-printed-robot-actuator/log/146045-motor-modification

https://hackaday.io/project/163766-low-cost-3d-printed-robot-tail/log/159509-timing-pulley

hello,
have you replaced the motor shaft with a longer one?
how did you do it?

Hi VALL_E

Yes, I replace the shaft

  1. Remove grub screw from motor bell.
  2. using a vice I press the shaft out.
  3. I buy some silver steel rob, cut it to length.
  4. I file a flat spot on the rod to match the one removed.
  5. I use the vice to press fit the shaft back in.

It is not perfect, but fine up to a few thousand RPM.

Thank You very much for the answer.
And how do You think what kind of motor will be better 750KV or 360KV. Both are on the market.
For example like thise https://aliexpress.com/item/32954160296.html?spm=a2g0o.cart.0.0.6fc43c00OY7VVg

The lower the KV the higher the torque but the lower the top speed.
That motor in the link has a 4mm shaft. A 6mm shaft is better.
Look at https://www.aliexpress.com/item/32517972556.html
or https://www.aliexpress.com/item/32549185150.html
They are my current favorite motors.

hello, which controller is the motor controlled by?
how to determine position?

It is my own custom controller. Details here https://hackaday.io/project/157812-3d-printed-robot-actuator/log/146170-actuator-controller-hardware
Uses an absolute magnetic encoder for motor position and then used as on offset for joint position

thank You for the answer.
But I can not assemble it by myself :(
Do You know some controller I can buy?

https://odriverobotics.com/
It also has a great discord channel.

thank You very much

How much is the ratio?

It is 24:1. Sorry it wasn't in the description.

Fantastic design! But I'm having trouble finding the actual inner / cycloid gears int he project files. I'm trying to import your Inventor project into Fusion 360, and it imports great, but the inside of the joint is just empty space (and floating bearings). It's missing the actual cycloid gears. Can you upload those? Or tell me what I'm doing wrong?

It was in the pack and go .zip file but in a different folder. I have uploaded the .ipt file called Main_equation_fixed_9mm it uses the parametrics in the Parametrics.xls file. I haven't used Fusion 360 before but I have read that it doesn't support equations, which is how I created the cycloidal gear. If you require the file in a different format or with different ratios/diameters please let me know and I can create stl or any other file(s) for you. What are you planning on making with this actuator?
Cheers, Paul

Thanks Paul! I'm thinking of using this in the shoulder and elbow joints of a robot arm I'm working on.

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What's the model of this motor? Or dimensions at least...

Multistar Elite 5010 or 5008 from Hobbyking but they are always out of stock
I'm using the Gartt ML5010 from gogorc now

Thanks!
I have some 6010 motors from older DJI drones, should fit.
Can you share the design files to I could do some alterations? I am considering this for a CNC.

Go to the thing files. The pack and go zip are all there. I'm making a stepper motor and timing pulley version right now and will upload it in a few days.

Hi there, I am really excited about your work and can not wait to see the timing pulley version. Would you be able to upload them anytime soon.
Have a nice day.

Hi htooh, I have add the missing files

Thank you! Excited to try printing this

It looks like a couple of parts are missing here, any chance you can upload them as well? I checked the ones from your other designs and they have 25 teeth and looks like this design requires one with 24 teeth.

The offset part which goes on the motor shaft is also not there, not sure if the one from the other design would work? Wasn't sure since the gear from the other design doesn't work.

Thanks for sharing this design and the others!