VEXPro - After the season [Archive]

Andrew Lawrence

31-03-2013, 02:24

Right before the 2013 season began, VEX surprised us all with an early FIRSTmas present - VEXPro. A lot of teams have used VEXPro over the season, and now that the only events left are week 6, district champs, and the Championships in St. Louis, I was wondering what teams thought of the products.

This year, we used the VersaWheels on our drivetrain, and have loved every bit of them. We've gotten through our fair share of pushing matches, and have had little if any wear on them. One may even compare them to colsons...

Also, I've been hearing some people claim the Ballshifters shift kinda slowly - does anyone have any information/feedback on that? We were looking into them next year.

z_beeblebrox

31-03-2013, 02:27

ttldomination

31-03-2013, 02:39

I'll try and break this down by how we used their products:

Wheels and Sprockets - While there really isn't anything special here, we used the VEXPro 6" wheels (with our own tread), and the entire DT was sprocketed using VEXPro sprockets. The system held up exceptionally well. There was only a minor failure, but I blame that more on how we did things. (Grade = 100).

BAG Motors - I suppose BAG motors are a part of the VEXPro line. We used BAG Motors early and were pleasantly surprised. However, we later received a nastier surprised when the motors started failing. It appears to be a common thing around FIRST and VEX has yet to nail down the issue. (Grade = 30)

Planetaries - These things are beautiful, customizable, and they build on each other SOOO well. There were some complaints about the piloting of the RS550s, but the issue is easily resolved. (Grade = 95)

My team is really hoping to get a chance to use their DT gearboxes at some point in the future.

- Sunny G.

Kevin Sevcik

31-03-2013, 10:19

By what we used:

VexPro Traction Wheels plus hubs and sprockets: These were great. Once I managed to explain the assembly order to my drivetrain mentor they went together in a breeze. I think the excellent piloting and sprocket alignment is the reason we hardly ever had to work on chain tension during the season.

Ball-shifters: We didn't have any problems dropping output shafts. The assembly turned a little tricky when my mentors decided to completely disassemble the things to see how they worked, but that's not a mark against the gearbox. The only trouble we had was with the encoder output solution. The press-fit between the output shaft, encoder gear, and bearing wasn't quite tight enough to be 100% no-slip. Our solution was a dab of threadlocker. I can't actually say how it worked because we never got the encoders tied into the control system, but it seemed likely to work.

Versaplanetaries: Great gearbox or greatest gearbox? Either way they're awesome. The ease of playing with multiple ratios made developing systems much faster. And I got to personally thank JVN at Lone Star when a topple took out one of our shooter motors and we had it replaced and running for the next match after a timeout. We would've been completely hosed if that happened with a P60 gearbox.

Billfred

31-03-2013, 11:00

2815 used the Mini-CIMs, the ball shifters, and two sprockets.

The Mini-CIMs were flawless in operation. Best design choice? Questionable...but that's our problem, not theirs.

The sprockets were solid. I appreciated having the tooth count on there, and we had no problems (other than needing a different tooth count on there--again, our problem not theirs).

The ball shifters didn't get nearly the use I expected--between sprocket size miscalculations and an odd binding issue that kept us driving in arcs, we had drive and cRIO brownout issues all season. Now that the robot is home and no longer in a bag, I expect us to have a fun session getting to the bottom of things. Might've been the ball shifters, might've been something else.

Adam Freeman

31-03-2013, 11:26

So far this season we have used:

- 4" VersaWheels on all (8) of our drive wheels, for both our practice and competition bots. They seem to be holding up really well, with minimal wear so far. Subjectively they provide good traction, outside of driving on the tape while trying to push up the pyramid pole (wheels are spinning in high gear).

- 2-Stage Ball shifters. The biggest benefit for us so far has been the lack of weight, allowing us to put it into other systems. Can't comment on the shifting, since we don't have pneumatics and haven't quite figured out how to shift them with a servo or motor yet (it's a work in progress). We dialed high speed to be very similar to our previous AndyMark supershifter setup (~14 FPS). I think low gear turns out to be a little faster, so that should be nice once we get them working.

Only concern we had with these was how the encoder gear was a press fit, instead of a more secure connection. We picked the two gearboxes that had the best press or had no apparent slip between the output shaft and the encoder gear and put those on our competition bot. We haven't had use for the encoders so far, but this may be an issue if we want to try and back up after we shoot our auto shots.

- VersaPlanetaries (100:1 and 300:1). We are using the 100:1 to power the feeder that pulls discs into the shooter, with an AndyMark 9015 motor. We also have (2) 300:1 planetaries w/Banebot 550s coupled to a 3:1 chain reduction to change the angle on our shooter. So far (knock on wood...), they have been great at moving the shooter angle and lifting the robot while hanging for 10pts. These little gearboxes are probably the best product offered in the entire lineup. The ability to mix and match ratios and adding stages to get the right setup is priceless. Not to mention the flexibility to work with every motor allowed is awesome.

Some improvements could probably be made to aid in assembly of the motor to the plate (as discussed elsewhere), but if care is taken you can everything lined up and running smoothly.

- Single stage, double reduction gearbox. We are running this on our climber with (2) CIMs and a ~4:1 chain reduction, to pull the robot up the tower. No problems so far...

As well as running all 888 Victors for every speed controller, and other misc harware (chain, bearings, sprockets, etc..) .

We have did not find a use for the Bag or MiniCIM motors on this years robot.

We're pretty much all in on the VEXpro lineup this season. We have seen no reason not to be 100% satisfied with the price, quality, and performance of any of the products.

MrForbes

31-03-2013, 11:30

We used the chassis-in-a-day, with single speed single reduction gearboxes and traction wheels with versa hubs. The gearboxes are working fine, although there was a bit of confusion during assembly, as the instructions didn't mention that one part was a press fit. Paul was quick to help by email, but it appears the instructions have not been updated? The wheels are a very clever design, I like the versa hubs, but we have had problems with the screws. It was not obvious that we needed to order a specific size of screw to attach the sprockets to the wheels, but we were able to use some of the left over screw assembly wheels for the sprockets. Unfortunately these screws are rather soft steel with button heads, and it's easy to strip the hex, and it's not easy to get them tight enough to not come apart. Thread locker would help. It would also help if the necessary screw lengths were noted on the ordering page on the web site. Perhaps add a drawing that shows how the wheels and hubs are assembled for the various configurations, noting what length screws are needed for different sprocket stacks. Or let us know that we'll have to spend some time figuring this out after we get the parts, and that we'll probably have to do some additional parts ordering to get the correct screws for our application.

I really like a lot of aspects of the design of the wheels, sprockets, hubs, axles, etc. It's obvious that many years of robotics experience went into the design of these parts.

MattC9

31-03-2013, 11:51

We used the chassis in a day, 6 versa wheels, sprockets, and the ball shifters. I only had a run with one of the products, the ball shifters. The ball shifter worked great!! After having to replace the output shafts we first got. 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. Easy fix right?? Just tighten some screws, well unlike all the other incredibly easy to access screws in the shifter you have to take the whole gear box apart to access the heads of the screws. This was incredibly difficult to do on the fly and during competition thank fully a pit crew member was able to spin the stand off in a way that tightened it up (and thankfully he also put some lock tight on it). Out of all the vex pro products the ball shifter was the only we had minor discrepancys with but with some use of lock tight it was all better. I can not tell you how much of a difference those ball shifter made this season they were truly great!

Tom Line

31-03-2013, 12:14

We're happy with a number of vexpro products we're using. The only item I want to mention is the traction wheels.

We're using the 6 inch version. We've seen a single problem: we're using 3 cims per side through a 3 motor toughbox. The fasteners holding the sprockets on have the wheels have worked loose several times, and are now on our list to check after each match. Our center wheels that have sprockets on both sides have been drilled out to 1/4-20 and through bolted. We haven't had a problem with those. We've stayed away from using locktight because I know it can react with the plastic with bad results.

I'm looking forward to trying the ball shifters this off-season. We usually don't use shifting drivetrains because of weight, but that may change now. I would absolutely LOVE it if Vex can look into supplying a kit that allows fast reliable shifting without pneumatics. In fact, with a little innovation, it's not impossible for the same kit to work on the supershifters as well. I've seen a number of solutions. The most elegant I saw was a single window motor with spring loaded arms (Hot in 2012). The servos are simply not powerful enough to shift under load. I've seen very few teams use them for exactly that reason. We plan on putting the ball shifters on our robot for the off-season to test them out, and will probably look at a solution at that time (we don't have pneumatics on this year's bot). There was a fellow at MARC last year with a really nice sliding arm linkage made out of lexan that was along the same lines - just bolt on a window motor and go.

roystur44

31-03-2013, 12:46

We used the Vexpro shafts on our manipulators. The .500 hex shaft is the bomb as well as the .500 round shaft. The dimensions are spot on and the pricing is great. Hope the prices stay the same.

The shaft collars worked out great as well as the bearings. The hexed bearings were out of stock so that hampered our design a bit.

The website was easy to order from and the CAD of the products where available to include in our CAD.

I would love to see a adjustable slip/magnet clutch included in the products. Being able to adjust the torque to a gripper or ball magnet mechanism is such a time consuming process.

I would also love to see some high powered servo's so we can build gimble, aiming and trigger mechanisms easily.

We used the 2013 KOP chassis. I would love to see a picture of the Ball shifters on a 2013 setup with belts and pulleys. Even better if it had 1.5" Traction wheels.

Two thumbs up for VexPro!

sanddrag

31-03-2013, 12:56

We used VexPro gears in a custom gearbox and VersaPlanetaries. Never a problem with either, other than one of 25 gears we purchased appeared to have been dropped and had a tooth dented, but it still would have worked fine. Very happy with the gears.

Adam Freeman

31-03-2013, 12:57

I'm looking forward to trying the ball shifters this off-season. We usually don't use shifting drivetrains because of weight, but that may change now. I would absolutely LOVE it if Vex can look into supplying a kit that allows fast reliable shifting without pneumatics. In fact, with a little innovation, it's not impossible for the same kit to work on the supershifters as well. I've seen a number of solutions. The most elegant I saw was a single window motor with spring loaded arms (Hot in 2012). The servos are simply not powerful enough to shift under load. I've seen very few teams use them for exactly that reason. We plan on putting the ball shifters on our robot for the off-season to test them out, and will probably look at a solution at that time (we don't have pneumatics on this year's bot). There was a fellow at MARC last year with a really nice sliding arm linkage made out of lexan that was along the same lines - just bolt on a window motor and go.

Tom,

We were planning to adapt out window motor shifter setup for the VEX ball shifters, but unfortunately the new small robot dimensions did not allow for it to package between the CIMs. I'm sure if we had last years size requirements I would have been able to make it work.

Unfortunately, I don't remember the mentors name right now....but, the smaller window motor setup was designed by a mentor on 107. It was a very nice and compact design.

So far I have tried designs to use both (2) VEX 393 motor or the (2)AndyMark servo setups. We thought we were having issues with the 393 stalling out and frying our digital side car, so we switched to the AM servo setup. Unfortunately, with the amount of play in the ball shifter shaft I haven't been able to get a good push/pull lever arm designed that shifts effectively.

One thing I've been trying to figure out is how it seems the shaft needs 5/8" of an inch to fully engage high/low gear, but a 1/2" cylinder is used to shift it pneumatically. The pneumatic setup holds that shaft much more securely, so my guess is the play in the shaft is the reason we haven't been able to di it correctly.

We're still working on the design and have another one to try out...but have put shifter development on hold until all our other issues (climber) have been solved.

Shu

31-03-2013, 13:13

We're using the 6 inch version. We've seen a single problem: we're using 3 cims per side through a 3 motor toughbox. The fasteners holding the sprockets on have the wheels have worked loose several times, and are now on our list to check after each match. Our center wheels that have sprockets on both sides have been drilled out to 1/4-20 and through bolted. We haven't had a problem with those. We've stayed away from using locktight because I know it can react with the plastic with bad results

We are also using the 6 inch traction wheel on a 6WD system with double sprockets on the center wheels and a single sprocket on the outside wheels. We are using the standard 8/32 fasteners with a lock washer under the head of the screw and have not had any problems with them coming loose.

This is our first year we went with hex shafts on the drivetrain and we have been extremely happy how everything went together with the versahubs. The only minor issue we had was with the initial hex bearings we received not being concentric. This was rectified very quickly with replacement parts.

Kevin Sevcik

31-03-2013, 14:16

We used Loctite Blue on our traction wheels and gearboxes and didn't notice any deterioration or anything. The australian version of Loctite's User Guide (http://www.loctite.com.au/aue/content_data/235564_Do_It_Right_Users_Guide.pdf)* says that the anaerobic threadlockers can be used on Nylon with a primer, so I have to assume it's okay for them to come in contact with the Glass-Filled Nylon that is used in the most of the VexPro line. Not so much the ABS used in the Mecanum roller mounts, though.

*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.

The Lucas

31-03-2013, 14:59

I'm looking forward to trying the ball shifters this off-season. We usually don't use shifting drivetrains because of weight, but that may change now. I would absolutely LOVE it if Vex can look into supplying a kit that allows fast reliable shifting without pneumatics. In fact, with a little innovation, it's not impossible for the same kit to work on the supershifters as well. I've seen a number of solutions. The most elegant I saw was a single window motor with spring loaded arms (Hot in 2012). The servos are simply not powerful enough to shift under load. I've seen very few teams use them for exactly that reason. We plan on putting the ball shifters on our robot for the off-season to test them out, and will probably look at a solution at that time (we don't have pneumatics on this year's bot). There was a fellow at MARC last year with a really nice sliding arm linkage made out of lexan that was along the same lines - just bolt on a window motor and go.

I originally sent this suggestion via PM to Adam, thinking it was just a possible solution to specific issue, not thinking it was really relevant to the general VexPro product recommendation topic. However, after reading your post I and Adam's other post, I think it might be on topic.

Electric Solenoid Actuators are legal for use in FRC since last season. See R32 for the specs and R70 for the maximum output of your Solenoid Breakout (alternatively, you can use relays). I speculate that the primary reason for this rule change was to facilitate shifting without pneumatics. I expected to see some teams use them or Andy Mark/VexPro to make a electric solenoid shifter kit. However, I haven't seen anything yet, maybe it is something they will develop this off-season (I dont know what the market is like for non-pneumatic shifters and the ball shifters are new this year).

There are many design considerations for electric solenoids including:
-Push vs. pull (this determines your default gear ratio)
-Return spring (to keep you in default)
-Solenoid package and mounting bracket
-Force vs. stroke (it varies, look for it in specs) enough to shift
-Wattage
It would be nice if one of the vendors engineered a nice solution for everyone to use.

Paul Copioli

31-03-2013, 15:12

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

31-03-2013, 21:43

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

01-04-2013, 01:58

... The australian version of Loctite's User Guide (http://www.loctite.com.au/aue/content_data/235564_Do_It_Right_Users_Guide.pdf)* ...

*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

01-04-2013, 02:33

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

01-04-2013, 04:32

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

01-04-2013, 13:36

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

01-04-2013, 13:57

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

01-04-2013, 14:04

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

01-04-2013, 14:21

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

01-04-2013, 14:32

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

01-04-2013, 14:44

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

01-04-2013, 16:46

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.

http://i169.photobucket.com/albums/u218/fox22photos/MiniCIMsonclimber_zpsc5bc8c16.png

thefro526

01-04-2013, 16:51

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

01-04-2013, 18:13

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

01-04-2013, 18:34

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.:)

Donut

01-04-2013, 22:16

topgun

01-04-2013, 22:50

We had several of the VersaPlanetary gearboxes on our robot and we liked the easy configuration between shaft output types and the multiple motor inputs.

The biggest issue we had with a couple of them was we stripped the hexagon socket set screw that tightened onto the motor shaft. I haven't determined if this was the students using worn hex keys, incorrect size hex keys, or what. If we tried to take the set screw off, the internal hexagon socket became damaged so that we couldn't remove the set screw. Maybe a different quality set screw would eliminate this problem.

Richard Wallace

02-04-2013, 01:35

The biggest issue we had with a couple of them was we stripped the hexagon socket set screw that tightened onto the motor shaft. I haven't determined if this was the students using worn hex keys, incorrect size hex keys, or what. If we tried to take the set screw off, the internal hexagon socket became damaged so that we couldn't remove the set screw. Maybe a different quality set screw would eliminate this problem.We used several VP gearboxes this year. On some (but not all) we found that an M2.5 hex key fit better than a 3/32", which is the size indicated in Step 3 on p. 8 of the VP User Guide (http://content.vexrobotics.com/vexpro/pdf/VEXpro_VersaPlanetary_UserGuide_20130305.pdf). Probably a higher quality set screw would help fix this variation.

AllenGregoryIV

02-04-2013, 01:44

We used several VP gearboxes this year. On some (but not all) we found that an M2.5 hex key fit better than a 3/32", which is the size indicated in Step 3 on p. 8 of the VP User Guide (http://content.vexrobotics.com/vexpro/pdf/VEXpro_VersaPlanetary_UserGuide_20130305.pdf). Probably a higher quality set screw would help fix this variation.

We have been using the M2.5 for most of ours and they have't stripped at all. I'm probably going to find a source for better set screws in the future and just replace them all.

I've also found some other variations in the gearboxes. I think we have bought around 12 of them and on occasion they don't have the alignment peg thing at all in one or two of the stages. We also had one of the snap rings come off and drop our shooter wheel to the floor. It was a quick fix but it did happen once. Like I said before they amazing and I wouldn't trade them for the world but they do have the occasional small problem.

JesseK

02-04-2013, 13:07

Preliminary Data:

Single Speed 12:64 Gearboxes with 30:50 VEXPro Gear post reduction
The didn't go together smoothly -- the 3/8" bearing wouldn't accept one side of the output shaft and the 1/2" hex bearing was too snug a fit for the other end of the shaft (started stripping the annodization off the hex corners). Used AM bearings in both cases to solve it. On the two VEXPro gears after the gear box, the annodization is wearing off fairly quickly -- possibly due to imperfect alignment, but the wear is even across the teeth. Will probably use the double reduction gearboxes next year, even though I liked the versatility of choosing custom gear ratios. Or we might use Gates or AM belts. Who knows. We really like all of the mounting options of this gearbox though.

22T Hex-bore Sprockets
We are using these in our drive train, geared for 12 ft/s. It's a typical 4WD WCD, with these sprockets transmitting power from front to rear in a 1:1 ratio. We've been hit hard twice, and both times had one of these sprockets eat itself a few seconds later while driving. It'd be nice if someone also offered a steel version that was hex broached. The first time we thought it was because the wheel block slid on the impact; the second time we verified that the block didn't move (so the chains were in proper tension the whole time).

Hex Shafts
We got the hex shaft stock, then sized them for our WCD drive train. Found that the shaft isn't perfectly straight nor an exact consistent diameter even over short runs, meaning that it doesn't "just work" with the hex broached VEXPro items. Sanding down the corners helped. Could have been a shipping / temperature thing. We have had the same issues with every hex shaft stock we've purchased. Imperfections were on about 50% of the shaft length, so about half of our shafts still have their nice annodized corners.

VersaPlanetary (Single Stage)
Used with BB-550 and AM-9015. Aggravated with the assembly. We're swapping a 550 out for a 775 to get a better PID responds on our tilt, so we'll see how the assembly works there. We also stripped a 9015 collet when a disc jammed early in the season, rendering the piece useless. We had a spare from the other transmission we got, which was a plus. I do like the interchangeable gears.

Versahubs
It's nice that the bolt pattern remains the same. It's kinda funny -- we have this hub and an AM hub on the shooter wheel since that was the best spacing configuration :D. Very nice for quick prototyping overall. We enlarged the holes for a #10 bolt since those are the smallest bolts we have in enough variety of sizes to do the prototypes.

Generally a mixed bag. May have more to say after Chesapeake & Champs.

Jared Russell

02-04-2013, 13:14

Akash Rastogi

02-04-2013, 13:27

thefro526

02-04-2013, 13:34

As a meta comment to all FRC suppliers this year I will say that one of my bigger frustrations has been with all things hex.

Finding straight, well-toleranced hex shaft that has an decent fit on runout- and wobble-free hex bearings/gears/sprockets has been a real pain. We had to mix and match hex products from VexPro, AndyMark, West Coast Products, and McMaster (and re-broach/clean up some pieces ourselves) to make assemblies that we could slide together while still being mostly runout/wobble free.

Just to elaborate on Jared's Post really quickly.

From what we've found (along with many others), aluminum hex bar tends to run a few thousandths oversize, usually somewhere in the .501-.503 range - a quick sanding with an Emory cloth or similar usually fixes this problem so it's not that big of a deal. Interestingly enough, 2024 Hex bar from McM does not seem to have this issue though as it runs a consistent .499-.500 over it's entire 3' length or so with very little run out. (at least the handful of pieces we've gotten)

Hex broached parts on the other hand are a completely different ball game. From what we've seen, WCP's parts run the tightest hexes at .501-.503, VexPro's hexes run on the larger end at .505-.507, and AM's stuff seems to be right in between the two. For some stuff, the difference in the broaches isn't a big deal, but if you're chasing backlash, that extra 5 thou in a gear's bore can get really annoying....

Cory

02-04-2013, 16:17

22T Hex-bore Sprockets
We are using these in our drive train, geared for 12 ft/s. It's a typical 4WD WCD, with these sprockets transmitting power from front to rear in a 1:1 ratio. We've been hit hard twice, and both times had one of these sprockets eat itself a few seconds later while driving. It'd be nice if someone also offered a steel version that was hex broached. The first time we thought it was because the wheel block slid on the impact; the second time we verified that the block didn't move (so the chains were in proper tension the whole time).

I'm pretty confident this is something caused by your design, not a defect or inadequate material. We have used 7075 22T sprockets for 7 years (of our own design, or from AM) with no failures whatsoever. 7075 is stronger than many steels, including some commonly used in sprockets.

Hex Shafts
We got the hex shaft stock, then sized them for our WCD drive train. Found that the shaft isn't perfectly straight nor an exact consistent diameter even over short runs, meaning that it doesn't "just work" with the hex broached VEXPro items. Sanding down the corners helped. Could have been a shipping / temperature thing. We have had the same issues with every hex shaft stock we've purchased. Imperfections were on about 50% of the shaft length, so about half of our shafts still have their nice annodized corners.

We have had the straightness problem with the majority of our hex shaft. We're almost 100% certain it is because it is shipped in a flat package that is extremely non rigid. A switch to round cardboard tube (like McMaster ships all shaft/rod/tube in) would likely eliminate this problem. We have not had issues with VEXPro gears sliding onto straight shaft though.

FrankJ

02-04-2013, 18:12

Planetary gearboxes are great.
Love the versa wheel hub system along gears & sprockets.
We ran 6" mechanums on a relatively light robot (100lb without battery/bumpers). Lost a roller on the comp bot & 2 rollers on practice bot. (Did I say I love being able to buy spare rollers? Change out is fast. I not really sure of the failure mode.
Love the fast shipping & customer service.

fox46

02-04-2013, 21:04

Can I ask a question--

Why is everyone using hexagonal shafts? What's wrong with a simple 1/8" keyway?

They're cheaper, easy to DIY, fit standard bearings, hubs etc.

thefro526

02-04-2013, 21:19

Can I ask a question--

Why is everyone using hexagonal shafts? What's wrong with a simple 1/8" keyway?

They're cheaper, easy to DIY, fit standard bearings, hubs etc.

In a perfect world* hex makes things much easier to assemble and disassemble, decreases total parts count and in some applications, is stronger/more resilient than a similar application.

Having used keyed components in the past, one of my biggest fears with keys is always losing the keyway during rushed assembly or disassembly of the system. It got to the point where the team I was on began loctiting keys into shafts with the hope that they wouldn't be lost in a pinch.

Beyond the lost key issue, there's also the fact that having a key/keyway in a part creates a major stress riser. I've seen a handful of 7075 1/2" keyed sprockets fail in the same system, all of which (from what I can remember) failed/began failing at the keyway. I'm not saying that all keys/keyways are bad, they're just not my thing.

*A perfect world being one where all hexes are the same size and hex bearings rain from the sky forever.

MichaelBick

02-04-2013, 21:21

Can I ask a question--

Why is everyone using hexagonal shafts? What's wrong with a simple 1/8" keyway?

They're cheaper, easy to DIY, fit standard bearings, hubs etc.

Hex shafts make assembly a lot easier. No need to deal with finicky keys. Hex is just as cheap as key shaft. It's still very easy to do in shop, as long as you have a lathe(many teams do). It's true that hex shaft does not fit standard bearings, but many times you can round the ends of the shaft. We have bought boraches for 3/8" and 1/2" hex, so we can hex anything we want.

Richard Wallace

02-04-2013, 21:35

... We have bought boraches for 3/8" and 1/2" hex, so we can hex anything we want.^This.

For the first time in years with FRC teams (starting 1996), a team I am part of built a robot using NO KEYS at all. Everything is 3/8" or 1/2" hex. (Well, the CIM pinions are still keyed.)

I also really like the 1/2 tube shaft. It makes quick-change dead axle wheel set-up very easy. Our wheels this year are AM 4" performance with 32T #25 sprockets. We cut-and-faced our axles 2.5" long, then set up the sprocket axial alignment using ABS spacers parted to the correct length on one side of each wheel, with a shaft collar on the other side. A 1/4" bolt through the middle holds the wheel-sprocket-axle assembly in place between our slotted frame rails, and a simple two-hole tensioner adjusts the C-C distance to suit the chain length. Wheel changes are really fast and can be done without removing bumpers. It's the little details that excite me. :]

Gregor

02-04-2013, 21:37

^This.

For the first time in years with FRC teams (starting 1996), a team I am part of built a robot using NO KEYS at all.

Wow, I want hex shaft CIMs :rolleyes:

Jared Russell

02-04-2013, 21:46

I forgot about the 1/2" tube shaft. Yes, that is extremely useful - with practice we can change out any drive wheel in about a minute.

ToddF

03-04-2013, 13:30

As a meta comment to all FRC suppliers this year I will say that one of my bigger frustrations has been with all things hex.

Finding straight, well-toleranced hex shaft that has a decent fit on runout- and wobble-free hex bearings/gears/sprockets has been a real pain. We had to mix and match hex products from VexPro, AndyMark, West Coast Products, and McMaster (and re-broach/clean up some pieces ourselves) to make assemblies that we could slide together while still being mostly runout/wobble free.

Amen. I wish to heaven above that the major FRC suppliers (AndyMark, VEX, WCProducts) would get together and agree on some standards for their hex products that would allow them to fit together properly and interchangeably. Hand fitting parts went out in the late 1800's, people. Hex shafting has the potential to be such a boon, and once everything is sorted and hand fitted, it's great. But, that sorting and fitting process is incredibly frustrating. We really try hard not to swear in front of the kids, but when it takes two days to put together something that should take two hours, there is a lot of under the breath muttering going on.

IndySam

03-04-2013, 20:42

I understand the desire to have standardized sizes but we must remember that these parts need to be cheep enough for us to purchase.

The tighter the tolerance the more the cost will go up, exponentialy.

Paul Copioli

03-04-2013, 20:58

The VEXpro 3/8" and 1/2" hex shafting was meant to do just that. They are designed as undersized shafting such that they fit into the hex bearings without the hand modifying.

The problem lies with the hex bearings themselves. We are working on this problem and we will reach out to AndyMark and WCP to standardize on the hex bearing size and tolerances since there is no standard for this in the bearing world today.

I am investigating the claim that the VEXpro 3' hex stock was oversized, because this is the first time I have received that complaint about the hex being oversized.

Our QC department has checked hundreds of the hex shaft and they all come within tolerance. We checked all of our hex gears on this shaft and they all "just work".

If there are cases where the shaft didn't work with one of our gears, sprockets, or hubs, please contact me and we can work it out with you. A lot of additional time, tooling, and development effort went in to making a custom hex shaft that holds the undersized hex tolerance so that it just worked without hand sanding and filing. As a side note, my team used tons fo the 1/2" shaft and we did not have to hand file any of the shafts to work with the VEXpro gears, hubs, and sprockets.

With regards to straightness, the 3/8" shaft definitely has some bow. partially, this is due to shipping methods, but mostly it is due to the process by which the shaft is made and the length to diameter ratio of the shaft.

It is possible to get much straighter shaft if the length is around 12" per part. If there is interest in the shorter length for a tighter straightness tolerance, then I will have my team investigate the possibilities.

Paul

Brian Selle

04-04-2013, 11:54

I was very impressed with the VexPro products we used. One of the things I appreciated most was the pricing. They started the whole thing... they lowered the price on the Victors/Jags and everyone had to follow. With quality, price and support, their site became one of my first choices when looking for parts.

What we used:

1) Versaplanetary gearboxes - Awesome product. Love being able to design the mount interface quickly with the idea that we interchange gear ratios and motors at any time. Slight issue aligning a AM9015 motor on one gearbox but it was resolved.

2) Gears - Very high quality, lightweight and strong 7075 AL, perfect. Used lots of these on our intake and shooter. Drilled and broached several of the 3/8" hex gears for a 1/2" keyed shaft on our shooter wheel.

3) Hex Shaft, Bearings, Collars - It was very hard to find 7075 3/8" hex shaft at the start of the season, they had it. We used a ton of 1/2" hex shaft, with no problems. We ordered 40 VexPro bearings - not so good. The shaft fit fine but was off-center and wobbled. We ended up using them on our practice robot anyway after the global shortage of hex bearings. This and the AM bearings being too small had me questioning the whole hex thing... I'm sure it will all be worked out next year. Used several collars, very nice and lightweight.

4) Pneumatics - While not VexPro products... I really appreciated the one-stop shopping and not having to spend hours figuring out the SMC and Festo catalogs.

Below is my VexPro product Wish List / Improvements for next year:

1) 8mm keyed CIM to 1/2" Hex adapter from 7075 AL - we made several of these ourselves using the 1/2 hex shaft. Would buy them if they were available... the $10 AM product is steel and too expensive.

2) Hex washers - we used these a lot of places, had our supplier laser out 0.050, 0.063, 0.090, and 0.125 thickness. VexPro has 0.125 delrin which is great... but need other thicknesses.

3) More gears! - 11 and 14T CIM motor gears from 7075 AL would be nice. Also 45T 1/2" hex and more 3/8" selections.

4) 1/4" flanged bearings and collars - we ended up with a bunch of these on our robot. There aren't a lot of choices... the McMaster ones we used are pretty awful.

5) Planetary gearbox shaft length - small thing but... we had to cut off the shafts and drill/tap the end hole on all the gearboxes we used. My first thought was that we could take them apart and put a snap ring groove on the lathe, but that was not happening, they don't come apart. Would be nice to have a couple choices in shaft length or perhaps a few snap ring grooves to use instead of the end screw.

6) Pneumatics - Single solenoid valve... would have bought several of these if available. Some air tanks would be nice as well.

7) GT2 pulleys - 9mm 1/2" hex AL and/or plastic pulleys would be sweet. Out with the chain... belts are here to stay.

8) Wavy washers for 3/8" and 1/2" Hex - Not a big deal to buy from McMaster but goes along with the drive train theme and one-stop shopping is nice.

9) Faster website - it's designed well and nice but a tad slow.

All-in-all I think VexPro hit a home run for FRC with these products and with time will only get better.

Steven Donow

04-04-2013, 11:56

An update from my post-the issues we were having with the motor mountings of the versaplanetaries coming undone seems to have been an isolated, onetime thing (probably due to my own lack of skill in tightening motors :D ). However, we have recently been experiencing issues with a BAG Motor through a 1:1 having it's set screw come loose...we're gonna try replacing it to see what happens, but hopefully this doesn't remain an issue...

AlexH

04-04-2013, 14:42

versaboxen: i love them. great planetary gearboxes. totally worth the money.

hex shaft, sprockets and other related hardware: haven't had a problem. like the tooth count on the sprockets only thing i don't like is the black shaft hides sharpie marks...

verawheels: i don't know what my team did wrong but our versa wheels lasted about an hour of practice driving and 10 matches before they were balded and had to be replaced. picture (http://upurs.us/image/47366.jpeg)

Gregor

04-04-2013, 15:23

Tom Line

04-04-2013, 15:27

nlknauss

04-04-2013, 17:37

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.

Sean, we were probably a good match there because we have similar setups :yikes:

2729 used the 8 wheeled (Versawheels) Drive in a Day chassis with the 5.33:1 single speed transmissions each driven with 2 CIMs. We basically followed the recommended setup process and had something together in no time. It took us a little while to get the recommended encoders, it would be nice if they were sold with the gearboxes as an option.

There was some maintenance we had to follow-up with down the line. We replaced the wheel alignment shaft collars with PVC spacers after seeing them start to shift. It is also on our check list to take a look at the CIM motors to make sure they are tight to the transmissions before we found a solution to the problem.

kmusa

04-04-2013, 18:24

like the tooth count on the sprockets only thing i don't like is the black shaft hides sharpie marks...

Sharpie does make a silver pen, which works well in this situation. They also have a line of paint pens.

ttldomination

04-04-2013, 19:06

verawheels: i don't know what my team did wrong but our versa wheels lasted about an hour of practice driving and 10 matches before they were balded and had to be replaced. picture (http://upurs.us/image/47366.jpeg)

All of my wat is this?

- Sunny G.

cadandcookies

04-04-2013, 20:19

7) GT2 pulleys - 9mm 1/2" hex AL and/or plastic pulleys would be sweet. Out with the chain... belts are here to stay.

I don't know how realistic this is, but PLEASE. I don't even care if they're slightly more expensive (though I know others might), this would have simplified our drive train so much.

I love belts, but chain is just so much easier for my team to do (not that we can't-- we did it this year with quite a bit of success, it was just a pain along the way).

I feel so odd for getting as excited as I am over this concept.

AlexH

04-04-2013, 20:48

Could you describe your drivetrain and driving conditions?

4wd 4cim 10fps all wheels were versawheels. drive conditions were, about an hour on carpet similar to FIRST field carpet and 10 matches...

T^2

04-04-2013, 22:11

Our experience with the Vexpro products:

Ball shifter gearboxes
Pros: Compact, light, and in our experience they shift more quickly than dog clutch shifters. They were also easier to mount than the AM Shifters we used last year.
Cons: The output shaft came out! Please fix this. We had to pin our shafts (through a hardened steel shaft housing, mind you) to prevent this from happening. It would be great if IFI could implement a mechanical connection between the steel housing and the hex shaft that would be removable so we could swap out shafts of different lengths. One of our steel shaft housings also had a hairline fracture on it, but this seems to be an anomaly. The encoder gear press fit is not very good, and eventually it was so slippy in the shaft that we couldn't use it without supergluing it in. Finally, it would be nice if we could have different spreads that outputted at appropriate speeds. The way they are now, the output speed is only appropriate for direct-driving very small wheels, without a third stage.

Motors
Mini-CIMs are awesome. BAG motors work pretty well (we didn't have failures with ours like some other teams did), but I wish they were a bit more powerful, perhaps on par with a 550. Side note: if you stall a BAG motor for a really long time, as we did in Madera, it'll burn out and smell as bad as anything you've ever smelled in your life. Sort of a sickly sweet fruity vomit smell.

VersaPlanetaries
Pros: Very easy to adapt motors of all types, even CIMs and Mini-CIMs if you need to. Swapping out gear ratios is very easy, as is swapping output shafts. We're never going back to BaneBots planetaries.
Cons: It's so hard to get 550s concentric! I know there's some play in the face plate mounting holes, but it doesn't work amazingly well. It shouldn't be that hard for IFI to include a plastic or aluminum centering ring with the gearboxes, like some teams have made themselves. Also, it would be nice to be able to put a CIM or Mini-CIM on a planetary without butchering it.

Gears, Bearings, and Shaft Collars
Flipping fantastic.

Shafts
Pros: They work well, when they work.
Cons: They're so bent, all the time. Out of five 3/8" shafts we received today, only two were within a straightness tolerance that we could use. This is fairly representative of all the shafts we bought during build season.
The 1/2" shafts are better, but not too much better -- one of three shafts we received today was bowed noticeably. We would happily buy 18" long shafts (12" might be too short for many purposes) if they were straighter.

Pneumatics
Can you also supply single-ended solenoid valves, please? Everything else is great, and easy to purchase.

VersaWheels
(Disclaimer: we didn't use these on our robot; only bought 1 with hubs for testing, so take this with a grain of salt. I also can't speak to durability over a season.)
Pros: Very cheap, easy to put together, and grips very well...
Cons: In one direction. When pushed from the side, the wheel slides without much resistance. Given that when we play defense, we often block with the side of our robot, this is an issue. Perhaps this could be helped by offsetting the W pattern like so:
---~~---
~~---~~
---~~---
~~---~~
Of course, this would probably make the wheel more expensive.

IndySam

04-04-2013, 22:42

We were pleasantly surprised by the offerings from Vex Pro. This was a good year for all FIRST teams by their addition.

Ball Shifter - We had several failures mostly self induced. The fitting on the solenoids are just too fragile and I would like to see them (or even the whole solenoid) changed. We also lost our chance at Boilermaker when the C-clip sheared off the end of the sifting shaft costing us two matches.
I'll be perfectly honest, with FIRST allowing so many good powerful motors to choose from, I doubt we will ever shift again unless the game screams for it. Six or even eight motor non-shifting drives may become the norm for us.

Bag Motor - This motor caused us many headaches this year. We started with four on our robot and ended with zero. I really hope the problems with this motor are solved, it's a nice package and has huge potential

VersaPlanetaries - A real game changer. Easy to use, easy to change and modify, by far the most significant new part to come to us in a long time. These little things took every thing we could throw at them. We used six on our bot from 1:1 to 1:300 with various motors. We abused them and they never let us down.

Gears - These low cost high quality gears enabled us to finally have our dream of a robot without chains. Our completely gear driven drive never gave us a second of trouble. The gears on our practice chassis still look almost brand new after many hours of use.

Lil' Lavery

04-04-2013, 22:55

Sean, we were probably a good match there because we have similar setups :yikes:
I'm eager to give it another go now that we've fattened up a bit. We weighed in at just under 97lbs at Hatboro when you shoved us. We were up to just over 110 at Lenape, but we never got in a pushing match with you guys there. Should be slightly heavier still if we reach Lehigh.

VersaWheels
(Disclaimer: we didn't use these on our robot; only bought 1 with hubs for testing, so take this with a grain of salt. I also can't speak to durability over a season.)
Pros: Very cheap, easy to put together, and grips very well...
Cons: In one direction. When pushed from the side, the wheel slides without much resistance. Given that when we play defense, we often block with the side of our robot, this is an issue. Perhaps this could be helped by offsetting the W pattern like so:
---~~---
~~---~~
---~~---
~~---~~
Of course, this would probably make the wheel more expensive.
We found the direct opposite with 1712. The points would dig into the carpet when pushed sideways, almost working like a cleat. We'll continue to observe this as the wheels continue to wear.

thefro526

05-04-2013, 23:37

Sorry I'm a bit late with this reply, been a bit busy competing...

Here's a picture showing the difference in tread profile between a well-worn versawheel and a brand new one. The wheel on the left has ~40 'official' matches on it, ~10 practice matches and some build season run time on it. It's noticeably slicker than a new wheel, almost as if the tread has glazed over.

http://db.tt/w0JJnuFi

Teched3

06-04-2013, 13:58

We went with single speed, 2 stage transmissions, and they have worked great on our competition robot as well as our practice bot. The only comments I have about Vexpro are:

The plastic transmission housings when we got them early in the season did not give good gear interface and were noisy. We immediately decided to make our own plates and spacers, and they have worked great. Nice and smooth, and no discernible wear on the gears.

The lack of sufficient inventory on the hex bore Versahubs (217-2592), which are still listed out of stock. Modified AndyMark hexhubs to our Vexpro wheels. The few we did get were great. Fit on the hex shafts though some were too tight. Used a Jewelers file and dressed the flats to get a good sliding fit. Next year we will machine the shafts to .500 d. and key to 1/8 as in the past for better concentricity. Initial shortage of hex bearings created a lot of anxiety as well.

Longer shafts on the ball shifters for wider wheels on WCD would also give more design versatility. We used an additional hex bearing in our frame on the shaft of the single speed tranny to take some of the load off the shaft bearings in the housing. Couldn't do that on the ball shifter due to the shorter shaft. :) :)

MrForbes

07-04-2013, 11:11

We used a complete Vex Pro drive system with ball shifters, drive in a day and traction wheels. Overall, everything works great (The shifters shift plenty fast), although the shifters do occasionally lose output shafts, but are easy to fix..

After the Bit Buckets' robot lost an output shaft in their last qualifying match, we made a quick crutch to try to prevent it happening in eliminations. This is the Rube Goldberg fix....good for entertainment value, maybe not the best solution to the problem, but they were still driving fine when they lost.

z_beeblebrox

07-04-2013, 12:10

After the Bit Buckets' robot lost an output shaft in their last qualifying match, we made a quick crutch to try to prevent it happening in eliminations. This is the Rube Goldberg fix....good for entertainment value, maybe not the best solution to the problem, but they were still driving fine when they lost.

Except, after our first elimination match, we learned that the screws holding the shifting piston to the ball shifter came loose. Because the shifters had to be disassembled to tighten the screws, it would have taken more than an hour to fix. We used a clamp to hold the piston in place for the last match. However, we had to stay in low gear.

Negative 9

08-04-2013, 05:00

We used the 8" VexPro Mecanum wheels this season with 1/2" round keyed VersaHubs and were pleased with them. Our robot only competed in 1 regional event but we never had to use any of our spare wheels or rollers. Our students loved not having to spend hours assembling them like last season and I loved the multi-pound weight savings we got in our drivetrain by switching.

And for reference, they just barely fit on the Andymark Nanotube output shafts for direct drive (I don't think we had to get the longer shafts, but that was a while ago).I was thinking about purchasing a set of 8" Mecanums for my team. I was just wondering why there is such a significant disparity in price between the ones VEXpro sell and the ones AndyMark sell. Does anyone know if there is a comparable quality difference as well?

JesseK

08-04-2013, 09:17

I was thinking about purchasing a set of 8" Mecanums for my team. I was just wondering why there is such a significant disparity in price between the ones VEXpro sell and the ones AndyMark sell. Does anyone know if there is a comparable quality difference as well?

As far as I can tell, there are two major differences:

Plastic (glass-filled Nylon) vs Aluminum body
Place of Manufacture
(tradeoffs here -- reference Andy Baker's 2009 Small Business lectures for advantages of local part sourcing)

It's all about final application, particularly with respect to #1. Neither is superior to the other without context.

IndySam

09-04-2013, 16:19

Just and addendum to our ball shifter woes.

After further investigation I believe that our problems were self induced and not the fault of Vex.

I don't think the c-clip was properly installed and that is what lead to it's failure not a problem with the shaft itself.

Tom Line

09-04-2013, 18:21

Steven Donow

14-04-2013, 10:12

Some more comments on VEXPro after this weekend:

Versaplanetaries-they held up completely fine for us(except for a busted 775-nothing VEX related) except at one point, the CIM output shaft flat out broke. Now, this could just be due to considerable wear of the shaft throughout the season, but we were lucky to have it happen to us at the end of the day with no matches left in that day.

Ball Shifters-Worked great as they did before, except for one match where the mounting screws of the pancake cylinder became loose, which was a relatively difficult repair. Also we experienced another issue that another team also experienced (from losing their pneumatic system for a match)-when the cylinders lose air, it seems that they default to neutral gear-it'd be nice if it were a spring return/release cylinder that defaulted to either high or low gear.