Our team worked on and manufactured a gearbox last season.
Here are the files: GrabCAD
The actual gearbox design is in the file boring.iam.
We have a doc with more information (including a brief description and a BOM) here: Info
Feedback is appreciated.
Good luck this season!
It looks good. I have a few thoughts/questions.
Why the complete enclosure? My team and a host of others have had success with open gearboxes
Why the non standard vendor? We source our gears, shafts, and bearings from Vex Pro
Why the keyed shafts? Just about everything we do nowadays is hex, and we do not look fondly on our days with keyed shafts.
What’s wrong with using the many standard options from Vexpro or Andymark? This gearbox is interesting but it’s using a lot of older FRC standards, like steel keyed shafts, full enclosures, and non-Vex/AM steel gears.
I can’t speak for the team, but what’s wrong with at least investigating that stuff?
Sure, there’s a lot of stuff that’s standardized. But failing to explore stuff outside the standards for either improvement or education is a recipe for not understanding why the standards exist. And, to be quite blunt, FRC standards are not the same as elsewhere (like industry–zero hex shafts, can’t tell you how many keyways/keys/key simulators, at least where I’ve been at).
What we have here is a team that is choosing to explore “new” options (“new-to-them”?) rather than go with the established standards, and people jump up and start asking why? I say, GO FOR IT! If nothing else, you’ll learn WHY the “standards” are the “standard”.
Given that this is happening just a few days before kickoff, I don’t think it’s a great idea to start breaking down all the advances in FRC and go back to the roots just in time for the season. The offseason is the time to test and compare results. There’s a very distinct difference between FRC and industry, so unless there’s a good reason to I don’t see a reason to break away from FRC standards (which evolved from industry standards, of course).
I’m a big fan of pushing the envelope, but only after you have something working. If a team has already tried Vex products and whatnot and hasn’t found them to their liking, that’s when it makes sense to push to me. Pushing it right before build season is much iffier.
EDIT: I just noticed they said they tried them last season. Presumably that means that they also worked fine, but I’m still curious as to why they don’t use any of the more recent COTS products instead.
+1
I agree completely. Hexes will save time and I think money, and they can avoid a failure point of the key. FRC uses them for a reason, and I think many teams could benefit from adopting this standard for shear ease of use rather than attempting to re-invent the re-invented wheel right before kickoff.
They said they did this LAST season.
So all they’re doing is putting it out so they can use it NEXT season (and asking for critique at the same time). It’s a season-old gearbox, offseason gearbox, etc. At this point in time I’d assume they’re just making sure they can use it again if needed.
“Not up to current FRC standards” isn’t necessarily a bad critique. But you do need to EXPLAIN something of why something that matches industry standard methods isn’t up to current FRC standard methods, for example: “Why use keyed shafts? Most teams these days use hex shafts because the keys can create failure points.” (Incidentally, a good answer to that might be “We have to ship hex shafts overseas, and the cost is a deal-breaker”, or any one of a number of other valid reasons.)
See how I edited my last post about 10 minutes before you posted yours… you may have been typing as I made that edit.
You’re totally right, understanding why teams do things is imperative. Especially when it comes to decision about drivetrains, gearboxes (like VPs versus other planetaries), and motors (CIMs vs. MiniCIMs and 775pros vs. BAG motors). In the interests of being more polite:
-Keyed shafts being failure points is a big one for FRC, especially when your key retention isn’t up to par. Hex shafts create more stress concentrations but the effect is minimal in FRC.
-Steel shafts and gears tend to be heavier than aluminum for little benefit, depending on where they are (I prefer using steel for smaller gears to prevent wear).
-Vexpro is much cheaper gears-wise than steel gears from non-FRC-specific sellers. So is Andymark is you want more larger steel gears. They also fit nicely in the hex bore family and have small face overall widths made for FRC.
-Fully enclosed gearboxes went out of vogue some years ago, for two reasons that I’m aware of: one, they would trap crud from the field and gear wear in the gearbox. Two, they add a lot of extra weight and sometimes make it harder to disassemble or repair
-Small CIM pinions, although smaller than many gears used in industry, can be used in FRC because the tooth profiles of all Vex and Andymark have been modified to accommodate them without causing mesh interferences like they would in industrial applications.
-Standardizing on Vex or Andymark might cost slightly more for parts like bearings, but it lets you keep things a lot more organized and centralized. I will use USA Bearings and Belts or Amazon from time to time if I need bulk bearings like R188s for elevators, but most of the time I use Vex for the convenience.