Added 0.5" standoffs on either side of the wheel, removed the ratchet, changed the left side plate to have a hole large enough to where all you have to do to remove the motor is unscrew the bolts and slide it out the side, changed the top plate to aluminum (so that it could be welded to the side plates), and made some things yellow for visibility. Current weight (CIM included) is 4.9lbs, and I would like to keep the module as a whole under 6lbs.
Looking much better! Your top plate still needs to be made stiffer somehow, but it’s not as important now that you’ve added standoffs; 3/16" should be enough.
How are the bearings for rotating the module going to work? Are they going above or below the pulley, or somewhere else?
Thanks! I think it has come a very long way from the first update I have a plan to make the top plate stiffer. The current bearing setup has a shaft collar nested underneath the pulley, a roller bearing nested into the top, a thrust bearing nested into the bottom of the steering plate, and another shaft collar where the steering shaft comes through the bearing in the steering plate.
What’s the thinking behind the really wide wheel?
Does it make sense to replace each of the standoffs with a plate that screws into the two blue colored side plates? They would triangulate your side plates in a different plane from the top plate making it less necessary to make the top plate more stiff.
Why did you remove the ratchet? Its "just’ another swerve module without it.
That’s what I was thinking, but I like the look of standoffs a little too much and space is limited on the side plates considering the CIM location and the other hole locations And don’t you worry, I just took the ratchet off for posting so as to not morally offend anyone (people reeeeeeally don’t like it). Final version will have it again
I like things that cannot be pushed. See below:
What sort of current draw will you be looking at to steer these wide wheels? From our experience in Swerve this year, we found that even minor increases of load at the module’s bottom edge were enough to brown out while steering.
How does one calculate that? I’m planning on using miniCIMs on VPs for steering, so I don’t think that would be an issue.
I’d recommend using the “Rotary Mechanism” sheet in the current JVN calculator. Identify how quickly you’ll need the module to turn, then do the reduction math to figure out stalling current, free current, etc.
Anything beyond that will take some familiarity with Physics, which I’d be glad to expand on once you’ve got the groundwork of understanding (current, torque, CoF, CoT, etc).
Will do! If all else fails, I could switch this back to crab again for the sake of having beefier steering gearboxes. But that likely will not happen
Crab is an interesting choice. When I use the word interesting, what I’m actually saying is that Crab is like a three wheeled motorcycle: All the risk and cost, with non of the benefits.
Go Swerve or stick with WCD.
What are some wheel widths other teams use?
Most teams will go with the COTS options, like Colsons or some other budget friendly wheel.
I’ve done a few (5?) robots with custom wheels, and to be honest, the cost and time just wasn’t worth the very marginal improvement. Unless FIRST changes the floor material (pleasegodnomoreregolith), I don’t see much reason to go away from the COTS options.
Now, as a design excercise, a wheel somewhere 3-4" in diameter with a width between 1 and 2" can’t hurt. It’s also one of the more simple objects to learn Simulations on.
I would have gone with a COTS wheel option, but with the motor being in the module it would just make it a bit too tall for my liking (I checked to see if the 1.65? Inch Colsons, but those are too small for the good bit of this module, and there’s not a snowball’s chance in hell I’m using stealth wheels).
I’ve been watching your project evolve, and I like how open you are to making changes and improving. You sure you’re still in high school?
Thanks man! Yessir, unfortunately still a junior in high school
Rookie year 2010?
Probably FTC or FLL is my guess.
Make sure you use a wheel with reasonable tread area. 3" diameter 1" wide wheel is about the minimum many teams go because otherwise tread wear becomes too apparent. Control systems and auton can get messed up if there are too many inconsistencies.
We used 2.5" colsons on our swerve this year. Drifting at 22fps wore through a set of four at each competition.
Would not recommend wheels at that size without the ability to easily change them out.