VEXPro 2014: After The Season

[Aren Siekmeier]

VersaWheel DT (3.25 Hex Bore)

We sort of fawned over these when they were released, due to their smaller diameter and the fact that they were all one piece, hex bore included, and did not require any additional hardware to mount a heavy, expensive hub. And they were dirt cheap, too, at $6 a pop. Unfortunately, they turned out to be worth about as much: on our practice bot a bit over full weight, we had them slipping at half power, not even close to the static friction supplied by our favorite blue nitrile. We promptly replaced them with 4" performance wheels from Andymark for our comp bot, which were well worth the 500% price increase. I have since heard some stories of the plastic VersaWheel tread melting to the carpet under the right slipping conditions...

HTD Belts and Pulleys

The selection here was great. We only used the metal hex bore pulleys, and I don't think this will change anytime soon... No problems with belt or pulley wear, though we did pop a few flanges off from hard impacts

VersaPlanetary Gearbox

We absolutely love these. The machining and finish is beautiful on every last part, and they are significantly cheaper and more flexible (for input motor options, ratios, and output shafts) than the P60s they have come to replace. Our only qualm was, as you mentioned, the plastic motor mount plates. Over tightening the screws (an easy thing for an unsupervised minion to do) led to fractures, as did, of course, using thread-locker (another common mistake when unsupervised). We also could have done a better job shielding the BAG attached to it from impact stresses. We saw 3 or 4 identical failures of the plastic mount plate, all of which also resulted in a bent BAG shaft as it fell out of the gearbox. We also invariably lost a sun gear or two in the process. So in the future, we'll be looking into replacing this one part with our own aluminum alternative. Still sure beats building your own gearbox

3-CIM Ball Shifter

After designing our own dog shifters the last two years, we decided to refocus our machining resources by going COTS this year. Turned out to be a good decision, since that sponsor had to bail on us last minute D: We selected the WCD option and had no problems interfacing it with our system. Though I still am a little baffled at the asymmetrical mount holes on the 3rd stage plate, considering how close they are to being symmetrical.

We also once ran into an issue with the encoder mount screws inside the housing coming loose, requiring us to completely disassemble the gearbox to super glue them back in (not a whole lot of fun). Perhaps these screws should thread all the way through the standoffs? Not positive exactly how to fix this without the super glue.

The plastic encoder gear on one of our 4 units did end up losing its press fit over time, so a keyed shaft may be worth considering. Super glue would also work just fine.

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In general, we were very satisfied with the price, quality, and availability of all our purchases. Impressive that all three of these were achieved when we're typically told to "pick any two." There were notable improvements in getting parts shipped out during build this season, and none of this affected us since we had ordered all the high priority drive items before build even started. However, the nature of the 6 week build still makes this a problem for some, since a 2, 3, or even 4 week wait can really be a killer.