6" Omni Wheels: We used 7 of these on our robots H-Drive this year. It was our first time using Omni Wheels and we were not disappointed, the wheels held up all year didn't have any issues with durability. The fact that the wheels shipped already assembled was also a huge time-saver.
Our only complaint was that we got quite a bit of material buildup (presumably from the carpet and plastic from the ramps) that proved difficult to clean up and negatively affected traction. We purchased a set of replacement wheels and swapped them out at the MSC as a precaution.
Single Speed, Double Reduction Gearboxs: We've used VexPro Ball Shifters before but this was our first time using the single speed gearboxes. The gearboxes held up all season and required no maintenance after initially assembly.
When we assembled the gearboxes, we did notice that one of the three gearboxes had some difficulty going together (the two pieces of the casing would not close all the way). Later after wiring up the gearboxes, we also noticed one of them ran very rough (sounded like grinding gears, and occasionally the gearbox seemed to "catch" on something). Disassembling and reassembling the gearboxes didn't provide a fix to the problem, but after running the gearbox under power for a while, the issue seemed to resolve itself. We're hoping to get the gearboxes apart again now that the season is over and see if we can diagnose the problem.
VersaPlanetary CIM Adaptor: Having had to make our own adapter (out of a solid block of aluminum) last year, the VexPro CIM Adapter is a welcome addition for our team. The weight savings is excellent and it held up surprisingly well to the weight of a MiniCIM cantilevered off the back of it, and along with a 35:1 Versaplanetary, drove
our conveyor system without any issues.
Colson Performa Wheels: When building our tote intake this year, we initially used 4" VexPro Traction wheels, direct driven by VersaPlanetary gearboxes with bag motors, to collect totes into our robot. This proved extremely ineffective during our initial tests, so we started looking for other options. We came across the 4" x 0.875", 1/2" Hex bore Colson wheels which seemed like they would be a great fit for our collector (having heard of how great Colson wheels are from other teams for years). While the Colson wheels were far more effective at grabbing totes then the traction wheels had been, they still didn't have the grip we were looking for, and additionally, the wheels started to wear down after our first competition.
We ended up replacing the Colson wheels with
4" Urethane Drive Rollers (60A) from McMaster for our last two competitions (thanks to team 314 for the idea) which worked much better for tote collection.
We have certainly not written off Colson wheels for future projects, but they were not a good fit for our robot this year.
Suggestions:
- Standardize wheel widths - Our initial robot design called for 6" Traction wheels, but after deciding to switch to H-Drive, we had to widen our drive base to accommodate the slightly wider 6in Omni-Wheels. Ideally, it would be nice if all same-diameter wheels were interchangeable with no modification.
- Make a shaft spacer that mates on one side to the VersaKey pattern in wheels and gears - I absolutely hate spacers in a drive system; there is nothing worse than having to chase after a dozen tiny rolling spacers when you have to swap out a wheel or fix a chain within a few minutes. Having spacers that mated to the VersaKey pasterns on VexPro wheels and gears would greatly alleviate this issue. I actually attempted to make such spacers myself using our teams 3D printer, but it proved problematic to build without dissolveable support material or hours of sanding off regular support material.
- It would be great if VEX stocked K1 Chain attachments for 35 chain (and 25 chain if possible). You can buy it from McMaster but it's 3 times more expensive then other sources (which have much slower shipping).