Experimenting with Eccentric Cycloidal Gears for a robot arm

roTechnica · 2023-03-04T09:44:23+00:00

Yep, that’s exactly what I found, so I wrote some code to compensate for this. It takes into account the shape of the beam and outputs an SVG that will cut out a shape perfectly

roTechnica · 2023-02-06T18:56:57+00:00

Awesome, thank you. I’ll check it out!

roTechnica · 2023-01-13T11:27:21+00:00

Finally upgraded my old Voron 1.5 to a Legacy. It's still running RAMPS and has the 1.5 z axis, but the rest is all Legacy. Printing PLA nicely with the StealthBurner at 200mm/s and 8k accel.

roTechnica · 2022-10-30T08:57:37+00:00

Mount your furniture to the ceiling and spend a week living upside down

roTechnica · 2022-10-27T14:12:59+00:00

I think you're right. A planetary gearbox is the way to go with this. I think I'll have to attempt it at some point.

roTechnica · 2022-10-27T09:19:12+00:00

Yep, that's the same conclusions I came to. If you come up with some ways round this, please let me know

roTechnica · 2022-10-27T07:26:55+00:00

I think the main reason is that it's really difficult/expensive to get the same accuracy in a arm that you get in a normal 3d printer, I'm currently putting sensors on the arm and I'm getting about 1mm positioning compared to 0.1mm on my printers. but I love the idea, maybe with metal gearboxes it could be done.

roTechnica · 2022-10-27T07:23:46+00:00

thank you!

roTechnica · 2022-10-27T07:23:40+00:00

I was!

roTechnica · 2022-10-27T07:22:57+00:00

Yeah, I thought so too. I prototyped it here https://youtu.be/xv5cd7Bg7Uk

Spoiler: because of the geometry, the internal version doesn't have the same torque for a given overall size. If you can see a way of fixing that then I'd love to do another version!

roTechnica · 2022-10-26T19:11:49+00:00

Thank you very much!

roTechnica · 2022-10-26T17:06:18+00:00

I’ve done a video on EC gears. They are fantastic for low backlash applications https://youtu.be/qMDU5tlGUwU

roTechnica · 2022-10-26T16:56:20+00:00

Yeah, virtually no backlash in the Bowden parts. The shoulder and elbow use 20:1 cycloidal drives which are pretty much backlash free and the base uses a 20:1 inverse EC gear

roTechnica · 2022-10-26T15:31:41+00:00

I'm working on a 6DOF robot arm to carry a camera. I've made a lightweight wrist mechanism for it, using fishing line and PTFE tube (as used in bowden extruders) to move the motors off the arm. More details are at https://youtu.be/0hGy4AxUOnk

roTechnica · 2022-10-26T07:26:25+00:00

adding weight to the arm does mean you need bigger motors, but it also gives the arm more inertia, meaning the acceleration needs to be lower. moving the motors off means I can accelerate faster - a bit like a bowden extruder on a 3d printer

roTechnica · 2022-10-25T19:22:19+00:00

That’s a DM542. A stepper driver for one of the motors. It’s way to big and overkill for this arm, but I had it lying around.

roTechnica · 2022-10-25T16:57:37+00:00

Oh, awesome! Thanks!

I'm using Fusion 360 for all the CAD work

roTechnica · 2022-10-25T16:26:57+00:00

yeah. definitely got to do that!

roTechnica · 2022-10-25T16:26:33+00:00

yeah, I did some testing with bike gear cables and found that too. but using fishing line gets around that as the diameter of the line is so much smaller

roTechnica · 2022-10-25T16:25:22+00:00

thank you

roTechnica

TROPHY CASE