VEXPro - After the season

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]

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..

[ttldomination]

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]

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]

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]

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]

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]

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]

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]

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]

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]

Originally Posted by Tom Line

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]

Originally Posted by Tom Line

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]

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* 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]

Originally Posted by Tom Line

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.