Spent the better part of 8 months on this project. Backlash issues had a significant hand in killing our 2023 bot, Voyager - a 2 jointed arm design - so I decided to see if I could stick a few nails into backlash’s coffin. Behold, the PyreCycloidal! Named for nothing in particular, I just like fire themes.
If the rest of the team allows it, yeah! The idea was to hopefully have an example assembled by the time our Bunnybots event rolls around, although the delivery time for the smaller bearings means that probably isn’t going to happen.
I’ll have fun looking at this later. Excellent design, getting the weight down to under 1lb is very impressive! The hardest thing about cycloids, apart from the huge BOM of pins and bearings, is the weight and size. It seems like you could cut down on the BOM by milling all of the pin profiles out of a single steel sheet, though this could increase the weight.
I had thought about this, but getting the proper end profile for them to fit in the sheet & getting the correct tolerances (the pins are oversize, for press fit) would have made the design pretty inaccessible.
The largest influence on the BOM is actually the ball bearings! I had considered jumping ship to a more novel type of reducer called an “abacus drive” which eliminates ball bearings from the BOM entirely (in favor of bearing balls), but it would have required cutting & hardening custom races, which just didn’t seem achievable with 2.5d machining.
If I can easily change the gear ratio I am definitely using this on an upcoming project. I’ve been looking for a good high torque gearbox I can make myself for a couple high powered projects lately, this looks to fit the bill!
Edit: Thanks for the cover, makes outdoors protection a lot easier!
Would love to see how it turns out! The project is fully parametric, so you should be able to change parameters pretty easily. The only restriction is the gearing ratio of the first and second stage has to be the same. (Edit: This is to prevent vibration. This need not apply if vibration is not a problem.)
Non-bearing parts are here! Time to start cutting.
Also, ordering the aluminum pieces from Fabworks. Cost comes to about $66 for all the aluminum plate (note that some post-processing is needed for blind holes, etc)
Project is not being assembled w/i the 2024 season. I might do this at home & order parts from other sources, but there’s no guarantee it’ll actually get assembled soon. The parts from McMaster came, but our person for handling business transactions never actually got to ordering the bulk bearings
