VEXPro - After the season

[Paul Copioli]

All,

The VEXpro wheel hubs (including Mecanum Wheels) are all made from glass filled Nylon. One of the many reasons we used glass filled Nylon was so that thread locker (specifically, Loctite 242 or equivalent) can be used.

We will make it more clear in our documentation, but in all cases when using steel screws with aluminum or steel mating parts, thread locker should be used. There is nothing in the standoffs inside the wheels to physically lock the screws.

I highly recommend using thread locker with all of our hex standoffs in all of the VEXpro wheels.

Paul

[AllenGregoryIV]

Versaplanteries are amazing and pretty much allow our robot to exist.

We're also using a full VEXpro drive train with the chassis in a day, single speed gearboxes (5.33:1), vex sprockets, and versawheels.

I will say that we have seen heavy ware on on our versawheels. The four that are on the ground all the time are practically round after our two regionals. They are first on our list of things to change out at Razorback next week. I still love them but we have worn them down enough to need replacement. At $5 a wheel I really wouldn't care if I had to change them each regional.

Also I can't say enough about how awesome their hex shafts and 1/2" shaft stock are for the price. Plus their hex shaft collars are awesome as well.

[kmusa]

Originally Posted by Kevin Sevcik

... The australian version of Loctite's User Guide* ...

*Also has a useful chart of metals that do and don't need a primer. In case you were wondering why your threadlocker with black oxide screws in aluminum wasn't curing.

*forehead smack* Well, that explains a lot. I usually wrote it off to the crud that is often present on our threads.

WRT the versaplanetary: the ease of reconfiguration and the range of output options are amazing.

Don't know about the other design constraints, but any chance the snap ring groove on the output shafts could be separated from the splined region?

[fox46]

I can't say enough how much I love the VEX Versaplanetaries. We are running a BAG motor with a 100:1 Versaplanetary to change the azimuth of our shooter and it has held up phenomenally through two regionals. Even after multiple falls off the pyramid where the former AndyMark gearmotor failed with a cracked carrier due to the shock load, it has survived with no signs of wear or damage. We are also running two 30:1 Versaplanetaries on our climber powered by miniCIMs. We were able to mate them up easily by drilling out the mounting holes in the mounting kit, machining the heads on a couple SHC screws to fit, trimming the motor shaft and adding a 2mm keyway.

In the future the team plans to go with 100% VEX products as we have yet to experience a single failure or defect.

[AllenGregoryIV]

Originally Posted by fox46

We are also running two 30:1 Versaplanetaries on our climber powered by miniCIMs. We were able to mate them up easily by drilling out the mounting holes in the mounting kit, machining the heads on a couple SHC screws to fit, trimming the motor shaft and adding a 2mm keyway.

Do you have any pictures of your system? We've done this too but your way seems different than ours and if I had to guess your way is probably better.

[Alex Cormier]

Originally Posted by AllenGregoryIV

Do you have any pictures of your system? We've done this too but your way seems different than ours and if I had to guess your way is probably better.

Do you have a snapshot of your wheels with wear?

[AllenGregoryIV]

Originally Posted by Alex Cormier

Do you have a snapshot of your wheels with wear?

I don't have any good pictures from our comp bot but I have attached a couple from the practice robot. They are not nearly as bad but still worn. That last picture is a new wheel for comparison.

[thefro526]

Originally Posted by Alex Cormier

Do you have a snapshot of your wheels with wear?

If their wheels have worn as ours have, the taller 'points' of the tread will gradually wear down and begin to round until they're even with the shorter 'points' of the tread. From there, the wheels seem to wear evenly - the points begin to round and will gradually get smaller until (I assume) they will more or less go away completely.

We first noticed the wheel wear after our first event, and rotated our front wheels to the rear to attempt to even out the wheel wear. From what we've seen, the wear may cause a minor decrease in effective COF when pushing forward, but not enough to be too worried about.

If there's an opportunity, I will get a picture of one of our more worn wheels on Thursday Morning and report back. It's also worth noting that we've played ~40 competition matches, maybe 10 practice matches and have a good 6-8 hours of additional run time on our competition robot's wheels. Odds are, a large majority of teams won't see this amount of run time until the Championship or after, so wheel wear may not be an issue for them.

*Edit, Allen posted pictures of 3847's wheels.... If anyone still wants more info, let me know...

[Alex Cormier]

Originally Posted by thefro526

If their wheels have worn as ours have, the taller 'points' of the tread will gradually wear down and begin to round until they're even with the shorter 'points' of the tread. From there, the wheels seem to wear evenly - the points begin to round and will gradually get smaller until (I assume) they will more or less go away completely.

We first noticed the wheel wear after our first event, and rotated our front wheels to the rear to attempt to even out the wheel wear. From what we've seen, the wear may cause a minor decrease in effective COF when pushing forward, but not enough to be too worried about.

If there's an opportunity, I will get a picture of one of our more worn wheels on Thursday Morning and report back. It's also worth noting that we've played ~40 competition matches, maybe 10 practice matches and have a good 6-8 hours of additional run time on our competition robot's wheels. Odds are, a large majority of teams won't see this amount of run time until the Championship or after, so wheel wear may not be an issue for them.

*Edit, Allen posted pictures of 3847's wheels.... If anyone still wants more info, let me know...

I'd like to see your photos too.

My concern is we ran FLR with a rock in our drive train, and for buckeye we took out the rock. My concern is that we have run 4 traction wheels in the front and omni in the back. We have the omni level or raised. Will the worn down wheels gives us a greater rock as the competition goes on?

[Lil' Lavery]

1712 used 6x VersaWheels, 1x 10:1 Versaplanetary, 1x BAG motor, 2x VersaHub (1/2" Round w/ 1/8" Keyway), 1x 60t #35 plate sprocket, and 1x 48t #35 plate sprocket.

The #35 plate sprockets:
Light weight, affordable, aesthetically pleasing, didn't fail in a relatively high load application (shoulder joint for our arm). No complaints.

The VersaHubs (keyed):
Would be convenient if alternatives to #8 screws were offered, in order to facilitate the possibility of transferring torque via the screws. Otherwise, no complaints.

The VersaPlanetary:
Our resuts seemed to run the middle of the pack with these. Useful, no significant issues, but not quite in love with them either. The variety of different sized screws required to mount the motor was confusing (both metric and imperial, really?). The motor shaft adapters for the AM-9015 didn't match the pictures in the assembly instructions. Additionally one of our students managed to snap the 775 adapter on our spare when tightening the set screw. Also, our spare binds when the mounting screws are fully tightened, so we have to leave them slightly loose. For some reason, this behavior differs from the gearbox on our robot.

The BAG motor:
We used a BAG motor through a 10:1 planetary for our initial shooter wheel at our first event. It held up just fine, but developed the open circuit issue during our unbag after the event. We have since replaced it with a AM-9015.

The Versawheels:
Overall, we love them. They provide subjectively good traction at an incredible price, and we haven't had significant issues with them. While we can't necessarily shove every robot we face out of the face (we can with a good chunk of them), we have only been displaced by two other robots the whole season (and one of which was while we were still <100lbs, and the other we were still ~110lb, both weights not counting batt/bumpers), 225 (6 motor drivetrain) and 2729 (2 speed drivetrain in low gear). Neither was able to move us with satisfactory speed either, ultimately resulting in them giving up and trying to drive around us.
The one comment we would make would be in regards to the description not mentioning the wheels are designed to be used with flanged bearings. We did not used flanged bearings, and one of our wheels has a tendency to visibly shift on top of the bearings when a side load is applied.

[Steven Donow]

So far (after only one event):
Drive in a Day Chassis-Awesome. Easy and quick, and we were able to mess with it as we wanted, ie. we got our own laser cut "sideplates" to raise the chassis up a few inches(this was to put an intake that we ended up abandoning).

Ball Shifters-So far, they've been great. The only issue we've had was the output shaft coming loose(it happened on probably 3/4 that we've had...but only once during an actual match), but that is easily fixed. The shifting is great, and combined with the sprockets and VersaHubs, it's so easy to change things to get any desired gearings.

MiniCIMs-we were originally using these on our shooter(we changed for purposes of wheels; nothing to do with VEXpro products themselves) and had virtually no problem with them.

BAG Motors-We're now using these for our shooter, and have yet to see any problems with them(in practice that is). We were originally using them on our intake, and never had problems with the motors themselves...hopefully we don't experience the problems people are talking about with them...

VersaPlanetaries-THESE ARE AMAZING!!!!!!! Changing reductions and motors has never been so easy, especially compared to needing pinions with Banebots gearboxes...We have one that is 15:1 with a 550 on our hopper and that has given us virtually no problems. Our shooter now is running BAGs 1:1 with them, and the only issues so far have been: on some of the gearboxes (4:1s I believe...) the little pin next to the assembling holes(I have no other way to figure out how to describe that) didn't line up, and we weren't able to make 1:1 gearboxes out of them. Also, occasionally, the screws that mount into the BAG motor have come loose. We retightened it and so far(after running them a large amount) they have yet to come loose. Also, the E-Clip on the bearing for the input...we also had the issue described above where the mounting collar flat out broke upon tightening the set screw too much...we also one had the bearing of the output fall out...

Traction Wheels-Great so far, nothing has gone wrong with them, except it'd be nice to see a simpler way of mounting tread, similar to the new AM Performance wheels.



Overall, VEXPro has been awesome stuff that definitely gave us a top of the notch drivetrain this year.

[fox46]

Originally Posted by AllenGregoryIV

Do you have any pictures of your system? We've done this too but your way seems different than ours and if I had to guess your way is probably better.

Here is the best I can do at the moment- this is a screenshot from one of our on-board GoPro cameras. The motors are attached using the mounting holes for the mounting plate as these are located on a 2" bolt circle. The threads were drilled out and two 10-32 bolts were used to attach the MiniCIM. The bolts were Socket Head Cap Screws. The bolt heads had to be machine to a smaller diameter to allow them to fit into the rear of the planetary. The shaft on the MiniCIM was also shortened to about 3/8" so that it would not impinge into the VersaPlanetary. We also inserted a 2mm keyway instead of relying on just the setscrew to hold the shaft.

[thefro526]

Originally Posted by Alex Cormier

I'd like to see your photos too.

My concern is we ran FLR with a rock in our drive train, and for buckeye we took out the rock. My concern is that we have run 4 traction wheels in the front and omni in the back. We have the omni level or raised. Will the worn down wheels gives us a greater rock as the competition goes on?

It's hard to say without knowing the exact specifics, but if you experience wear like we did, it will have an effect on how the robot appears to 'sit' on the floor.

In our case, we found that the wear on the rear wheels was enough to cause the front of our robot to sit up from the floor ~1/8" or so - making our intake appear to not work as intended...

One easy solution to the wear problem is to periodically rotate the wheels between ends/corners/etc. In our application, an 8WD with .090" drop on the center two wheel pairs, we've found that the rear most pair and the rear center pair wear the fastest (under the center of mass), the front center pair wears a bit slower, but not by much, and the front wheels barely wore at all. The simple solution was swapping the front and rear wheel pairs between our week 1 competition and week 3 competition. Luckily, our drive is set up in such a way that it allows for wheel swaps in less than 2 minutes or so.

[Alex Cormier]

Originally Posted by thefro526

It's hard to say without knowing the exact specifics, but if you experience wear like we did, it will have an effect on how the robot appears to 'sit' on the floor.

In our case, we found that the wear on the rear wheels was enough to cause the front of our robot to sit up from the floor ~1/8" or so - making our intake appear to not work as intended...

One easy solution to the wear problem is to periodically rotate the wheels between ends/corners/etc. In our application, an 8WD with .090" drop on the center two wheel pairs, we've found that the rear most pair and the rear center pair wear the fastest (under the center of mass), the front center pair wears a bit slower, but not by much, and the front wheels barely wore at all. The simple solution was swapping the front and rear wheel pairs between our week 1 competition and week 3 competition. Luckily, our drive is set up in such a way that it allows for wheel swaps in less than 2 minutes or so.

Yeah, Understandable.

It's not a quick thing to change out wheels for us, probably about a 20-30 minute time frame. I was thinking about buying a pair and making the secondary chassis of this years bot with the vex wheels. The 2013 chassis is the best one we have made and we have spares of just about all pieces.

Are you running 8wd?

Thanks for the information.

[dyanoshak]

Originally Posted by MattC9

When our event rolled around our driver put those things to the test and near the end of quals on Saturday he had trouble shifting on one side and started to drive in arcs. This was due to a loose piston mount.

Well, we did have a loose piston, but the issue was actually due to a poorly assembled power pole on a Jag. That side of the drive train was driven by only one CIM during that match because that one Jag wasn't powered.

The piston was probably loose all day before we noticed it. The Ball Shifters worked well even with one of the pistons hanging on by a few threads.