Early models of mechanum wheels had LOTS of maintenance/failure problems. We’d have to buy a spare L-R swap-in pair, and a wheel’s
worth of parts, just to keep them running.
But it’s been over a decade since one of my teams used Mech, due to the maintenance horrors.
2023 - My current FRC team wishes to do Mech for the first time, and wonders:
1)“How good are the CURRENT gen of mech wheels TODAY?”**
Teams – Please share your FRC Mecanum experience stories (Up/Down) with the RECENT models. IOW:
Of the current gen 4-6-8” Mech wheels, WHICH brand(s), model(s) (AM, Vex, other) & sizes now perform (&survive) the BEST in FRC,
and which makes&models are/were maintenance nightmares and should (IYHO) be avoided? (Please be honest, not PC).
Which brand, model & size would you RECOMMEND to a "FRC Mech Rookie” for the 2023 FRC contest?
BTW… If possible, PLEASE suggest a COMPLETE, DECENT system
(IOW, please include your suggested motor-gearboxes, controllers, encoders, et al. I need to cite drive cost to the team.)
What SPARES must we stock? IOW, If the current gen mechanum wheels STILL won’t survive a FULL season [incl championships], do we STILL need to stock “at least a spare LR pair (for quick pit swap) plus a wheel’s worth of small parts (for rebuilding)”, JUST to keep “the darn overly fragile wheels” running?
(Or, has the fragility finally been solved?)
Just to be clear, are you looking for mecanum wheels to use in the drivetrain or as part of an intake?
For intakes, we had the best success with the Vex ones last year. Over the course of the season we also used the AndyMark SD set and AndyMark HD set, but found that the SD was too lightweight and the HD was too heavy. The Vex ones gave a good balance between weight and durability. This will definitely depend on the specific mechanism and game piece in question though.
For a drivetrain I don’t have as much recent experience, as the last time I used a mecanum drive was 2015. We used the Vex 6" wheels then and were happy with them, and I don’t think the design has changed all that much since then. In terms of durability, the AndyMark HD wheels seem to be strong enough to take the weight of an FRC robot, but I don’t have any firsthand experience using them to drive. The AndyMark SD and BB wheels are likely not strong enough for an FRC drivetrain.
We use mecanum a lot
The Andy mark wheels are great, and the vex ones are literal garbage.
Andy mark makes them now with steel around the edges so the flanges don’t bend at all.
They have a few different options, the new smooth rollers are beautiful. I recommend those.
And for what it’s worth, I’m ready to bet another ice cream sundae with @Richard_McCann that robots with mecanum on their drive trains have their best showing since 2015, with at least one captain of the #1 seed winning a regional or district event on them. I’d use the 6" versions this year due to the ramp angle on the charging station.
As long as they gear for a high top speed I agree. If you’re fast you’ll be able to zip thru the middle quick enough. There are more protected zones than in 2017 and there were some solid mecanum gear runners then too.
It’s probably in your best interest to keep some spare rollers or even a spare LR pair. Weirder things have happened on the field then wheels breaking and I doubt that’s how you want to end a competition. I may be acting a little over dramatic but I always prefer having spares, especially for the drive train in the pits.
Used VEXPro 6" last season. Played three events, replaced them (full set, not just one LR pair) once. I recommend using an aluminum rather than plastic VersaHub with them since the plastic ones stripped about halfway through the second event. Also used the VEXPro Single Reduction Clamping Gearbox with the bearing block they come with, geared 12:72 and 30:66.
I can’t in good conscience recommend purchasing and building this setup, because VEXPro, but I will say I had no complaints about how it drove. When it worked (read: before those plastic VersaHubs gave out) it worked like a dream.
Update: Per the suggestions here (THANKS!), we’re trying an AM set this season, with a spare L/R pair. Yes, they’re MUCH better than the old ones!
Currently the Drivetrain group has our old plastic belt sprockets on them, which does make me a bit nervous).
Not sure if we ordered any metal hubs or spare parts to rebuild a wheel. Without rebuild parts, you’re basically in a “one failure per event” situation with between event rebuilding (unless exactly one Right and one Left fails).
Can anyone suggest “how much of what” in AM mech wheel spare parts we should have on hand, for rebuilding?
What is the most common failure mode these days?
A decade ago, we mostly replaced the “fragile axles” that bent or broke, but occasionally we did have to straighten out the metal frame’s tabs slightly to prevent roller binding. I’m hoping the current metal frames are better this year.
Wheel rollers rarely needed replacement, unless they were damaged internally by its axle’s failure mode.
Wish us luck!
Suggestions as to a decent “repair part mix” would still be appreciated!
Keith Mc. - Mentor (and sponsor via ACTI), 6101 Strange Quarks