VEXPro 2014: After The Season

[JesseK]

VersaPlanetary
Used 2, both with BAG motors. One was a 7:1 reduction going to 1.75" Banebot green wheels for our intake. The other was 100:1 to our winch system. Both went together in less than 5 minutes, both worked flawlessly for 3 crazy events.

VersaHubs
We used a lot of different hubs during prototyping. Yet it turns out we only had 2 sprocket hubs on the entire production robot, and they weren't used for sprockets . Dog gear, anyone?

Colson Wheel Hubs
I like the WCP version over the longer VexPro version, yet both worked great. I would like to see VEX Pro (or someone we use often) start carrying Colsons so we don't pay $26 in shipping for $60 worth of wheels.

1/2" Hex Axle
We had an issue with the 36" version of these coming in bent slightly over the 36" length. We were unable to ascertain if this happened during shipping. The straighter 18" version was used on our intake, and the 36" version wound up being a nice lightweight strong set of arms for our catapult.

Framing Plates
Used for ridiculously fast prototyping. Only a couple made it onto the production bot, but they were in key positions and held up nicely.

Hex Shaft Collars
Love them. Love how thin they are, love that they work flawlessly and love that they're black.

Hex Bearings
Used a mix of AM and VEX Pro bearing on the final robot. I think we tacked them on to the orders that were going in at the time, so there was no real engineering reason for one supplier vs the other. All hex bearings worked great though.

Excited For Next Year
1885 mentors are very cautious early adopters. New technology represents the opportunity to take a risk and we limit our risk by limiting the amount of brand new product releases in a given season across all of our suppliers (VEX Pro, AM, WCP, etc). Admittedly only 25% of post-season risk evaluation is from talking to teams - the rest is based upon anecdotes from CD. We only do this because we have over-used "new" products where we apparently overlooked "proper" use in prior years. With that said, here are the "new" VEX Pro items which were thought about this year and will move into our "low risk" evaluations for next year

WCD Bearing Plates (outright excited, to be honest)
WCP DS Gearbox (final config TBD)
15mm HTD belts (general), or 9mm HTD belts for light applications
Bevel Gears for intakes

[audietron]

Drive in a Day 2014

This frame is very good. We were able to mount the 3.25 wheels nicely for an incredibly low ground clearance. It was convenient for just about any thing we needed to mount.

Versawheels dt (3.25)

These wheels were great for the most part. I like that they have the hex bore but our problem with them was that we would have traction for about a day of competition matches. This meant we changed out the wheels friday night and would have some traction issues during eliminations because of the large amounts of defense. It would be awesome if they made the spike tread into hex bore and 3.25.

P.s. (A live axile version of the 4 inch mecanum wheels would be great for an off-season project we have.)

[BrendanB]

Overall I was impressed considering I was very disappointed by some of the quality from last year in the two-CIM ball shifters and Versa Wheels.

After weighing the pros and cons with our mechanical team we decided to go with the 3 CIM Ball Shifters after discussing what the failures were from last year and how we could prevent them. We narrowed it down to three areas all of which had fixes. To combat our biggest issue from the year with the output shafts falling out (including the replacements) we immediately pinned the shafts this year as a precaution. The second was the odd design of the encoder standoffs having the screws on the inside of the shifter housing. Last year we had a few on the inside come loose and destroyed our encoders. We put some Loctite on these bolts and made sure they were nice and snug before assembly. The last part was swapping for the updated encoder gears after the original press fit ones came loose. We replaced these gears in week 6 but the original two mods were done in minutes during assembly. Overall they were the most reliable shifting gearboxes we have used in four seasons and they lasted through our longest competition season of the year running in 5 competitions and hours of practice without failure.

My only suggestion would be to revisit the mounting of the encoder to eliminate the interior bolts on the standoffs because you can't tighten them without ripping the whole thing apart.

We were very satisfied with the other products we used and the only issues we had were with our VersaPlanetary gearboxes but they weren't assembled correctly the first time around which was our fault.

[Chris is me]

VersaPlanetary Gearbox + BAG

These gearboxes are really awesome. Very easy to put together, mounts a number of different ways, and gear ratio changes are a snap. We designed for and bought one ratio, tested it, and then decided we wanted to up the torque a bit. All we had to do was buy another gear set, take it apart, swap it in and go. Assembly or a gear swap is a 30 minute job for freshmen whom had never assembled a gearbox before. These are great for prototyping as well. Cool bonus: An 18T HTD pulley fits right on it with plenty of belt clearance even if side mounted.

BAG Motor we had no problems with. Robust, never got warm, no finicky motor leads to deal with, etc. That said we did not apply much load.

Mecanum Wheels

Did not use these on the ground, so I can't comment on their build quality under drivetrain loads, but these wheels were killer on our intake this year. I think these made us the best pickup at our events. Rubber is grippy and Colson-like on these rollers; great grip on this year's game piece. The weight wasn't too bad either. We'll definitely be playing with these on manipulators in the future.

VersaFrame 1x1 .04" wall

The Good: Hole pattern stock is awesome. Not having to drill in a pattern saves so much time and is so easy to play with. We initially used it for our roller claw as it was versatile enough to let us change geometry around. All in all a pretty awesome system.

Don't let the relative length of these sections fool you: I'm a fan of the VersaTubing and would buy again, particularly if it came in different wall thicknesses or hole diameters.

The Bad: .04" wall is only good for some really specific no load applications. Obviously this stuff shouldn't leave the bumper zone but even inside a frame you need a well supported system to survive any kind of impact or cyclic loading.

When we designed the claw using this stuff, we knew that many / most members would not be robust enough to last through competition. We decided we would replace members that broke on the practice bot with thicker wall members until we stopped breaking things. I'm not criticizing Vex for our use of the product outside the bumper zone as we knew what we were getting into and designed the rest of the claw to be strong (solid standoffs, flat "belly pan" pieces to tie things together, etc).

The very thin profile is weaker than I could have imagined and failed in very interesting ways. We used screws mounted to one side of the tube (tool clearance on the other) to retain a dead axle that our intake pivoted about using pneumatics. The axle holes here, as well as the holes that we mounted the pneumatic pivot to, deformed under cyclic loading to the point where the holes were noticeably ovalized and the mechanism had significant slop. We fixed this by adding material to those areas - usually with a thicker gusset plate - but even 16 wall tube had this problem far less than the Vex setup. We also found that over tightening a bolt going through both sides of the tube would very quickly cause the tube to sink in or pull out, without much resistance to warn you of what's happening.

We had our pneumatic pistons mounted to a plate which we riveted with four rivets to a set of 2x 1x1 tubing. The force of these pair of 3/4" bore pistons at 30 PSI was enough to rip the tubing outward, eventually shearing rivets right off. Upgrading to 3/16th rivets helped with the rivets not breaking anymore, but the failure moved to the tube instead of the rivets! We found this was the case with this tubing - if you upgraded to high strength 3/16" aluminum rivets, the tube would plastically deform dramatically before a rivet would break.

VersaFrame 2x1 .1 Wall

We didn't use much of this stuff (just on the shooter), but it was really nice. .1 wall is a good compromise between 1/8" and 1/16" wall material that's commercially available. Again, the built in hole pattern is awesome. We didn't have much need for the alignment lines on the sides but those are a nice addition for locating hole centers and an easy way to tell at a glance if a hole is "dropped".

VersaFrame Gussets

Also excellent. Just the right thickness at .09. Easy enough to drill out to whatever rivet size you feel like using. Saved us a lot of time making these on a router or the haas. The End Bearing Gusset is a really cool and rigid way to put a roller on a stick. The bent 90 degree Angle Gussets are incredible. This is a very hard part to make for us as it requires precision bending, but it's been a part we've always had a need for in odd places. Allowed us to strengthen a small unsupported section of claw tubing very easily. Bearing hole is a cool bonus that I'd like to find a use for someday.

VersaChassis in General

The 5/32" hole pattern was kind of awkward. I would have much preferred a hole pattern for 3/16" rivets that could be drilled out to #10 clearance. #10 hardware and 3/16" rivets seem to be the standard in FRC for a lot of teams. It's fairly easy to find rivets in that size and you can get a variety of different kinds (colored rivets, high strength aluminum, etc). 5/32nd rivets that we used are a bit weird and didn't have the large grip range we were used to with 3/16" rivets.

Overall, I would like the system a lot better if it used a 3/16th rivet hole pattern and if the 1x1 was available in .063 and .1 wall as well as .04 wall. Either way though, it's a very cool system that can really help teams out regardless of resources. We'll be using these products in the future. Perhaps with our own 1x1 tubing though.

HTD Belts & Pulleys

We decided that the quick lead time of Vex belts in build season was worth switching from GT2 to HTD even if it is a theoretical downgrade. We used 15mm Vex belts with 24T B&B pulley stock in our drivetrain. No problems whatsoever to report. No ratcheting, performance changes, or otherwise. Exact centers with 15mm belts are a very good system for FRC drivetrains.

We used a 9mm belt with 18T pulleys on the claw roller. We used CAD to model an exact center distance between parts in an assembly and it ran just fine with no problems. Pulleys were light and durable. The belt subjectively seemed looser than one might expect but it ran like a champ. I don't think I would want to manually tension these belts and just guess the "right" tension when exact numbers work so reliably. These belts aren't going to stretch in an FRC season.

Vex 1/2" Hex Shaft

This stuff is awesome for 99% of use cases. Being able to slip fit through any hex bearing is just so awesome. Saves us hours of facing down our hex shaft stock to fit through bearings. They can't take any load thrown at it (obviously) but they have merit. Subjectively the way these shafts failed didn't quite "seem" like 7075 of a proper temper - the alloy may have been slightly off or untempered? If that was the case though it was close enough not to notice until you were pushing the limits of any 7075 shaft.

A specific problem with these shafts is mentioned in the next section.

Vex Gears

These are great. I love the standard width and the noticeably improved efficiency over competitor's gears. Aluminum gears are also extremely light. In our drive they took whatever we threw at them, and didn't wear much with white lithium grease applied.

These gears do have a problem with our specific use case for them. In order to fit in "any" hex shaft, the hex bore is a bit loose / oversized in these gears. First, I just want to say that it makes no sense for the hex bore in a ball bearing to be tighter and more precise than the hex bore for a gear. Why not use the same oversize broach in the bearings? Second, this loose broach creates a bit of inherent slop / backlash that can stack up very quickly. We made a six stage arm gearbox with .003" added to the centers and using the Vex hex extensively. The slop in the gearbox was compounded so badly that the arm had literally 7 degrees of slop. This was very difficult to fix after the fact and ultimately we replaced the geared arm with a winch-down system because of this slop. This isn't an issue in common 2 or 3 stage gearboxes, but it does prevent us from doing an entirely geared arm which had its advantages. Oh well.

Ballshifter Shaft

We used the shifting hardware from a Ball Shifter this year on our winch and overall the system worked well. It did not need a substantial amount of pressure to release our 80 pound CF spring shooter. There was wear on the gears and shifting plunger over time but it took several hundred shots for it to become a problem and replacing shifting hardware was cheap and easy.

The mechanism to couple the ball shifter to its shifting piston is inherently flawed. A tiny bearing and some rotor clips are clamped on by a plastic device which also captures the piston rod and nut. The bearing did not take radial loads well and ended up seizing. The rotor clips sheared several times with only 30ish pounds applied to the mechanism. We did end up using a 1.5" bore piston with the device regulated to 30 PSI, so forces were a little bigger than a normal shifting piston, but if the setup is that borderline, I would not trust it in a drivetrain either. We ended up making a cool custom coupler designed by our head mentor that used a bigger bearing. We had to thread the end of our Ball Shifter plunger shafts and install a flanged cylinder onto the shafts to retain the ball bearing one way. We used external and internal snap rings to retain it in the other direction. Once we upgraded this piece, the shifter worked pretty much just fine.

I wish the balls wouldn't cut into the gear or shifting plunger so much. Maybe a less hard set of shifting balls could be used, or a steel plunger.

Also, the hex shaft on the end just slid out one day on the practice field. Pretty annoying. We applied some Red loctite and fixed it but there should really be a cotter pin or something.

We found that over tightening a bolt going through both sides of the tube would very quickly cause the tube to sink in or pull out, without much resistance to warn you of what's happening.

Colson Hubs

These are still awesome and they look even better in black. Some teams (20) noticed that the OD was a bit small for a good press fit and that they could slip the press fit before the wheels slipped on the ground in extreme cases. Knurling the outside fixed this. We didn't encounter this problem, but a bigger OD would help prevent teams from running into this problem. Otherwise absolutely no complaints.

Hex Shaft Collars / Spacers

LOVE these shaft collars. Very light, thin, and a good range from tight to loose. These are so useful. The spacers also proved really useful too. Just having hex broached plastic spacers in your toolbox is so much cleaner than making something out of PVC or whatever. Will buy both again.


All in all, happy with the Vex product line this year.

I do have to say, lots of teams are very critical of Vex's belts because of snapping in the drivetrain. I've very much noticed a common denominator between these scenarios- Teams used 24T, 9mm belts without exact centers in their drives. This is simply not a good design for FRC. 9mm belts with pulleys that small are drastically undersized for the application. Using tensioners makes unequal tensioning, overtensioning, or undertensioning very possible which can make these problems worse. You would have failed Gates belts or SDP-SI belts too. I don't know if Vex belts had manufacturing problems or not, but using 9mm belts and small pulleys in the drive is asking for problems. Trust me, go 15mm.

[Trent B]

Originally Posted by Chris is me

Ballshifter Shaft
I wish the balls wouldn't cut into the gear or shifting plunger so much. Maybe a less hard set of shifting balls could be used, or a steel plunger.

Neutrino remade the shaft in mild steel as well as in stainless (I think 300 series). Both still had significant wear from the balls.

We are thinking of making a hardened tool steel shaft for off seasons, but that may just transfer the wear to the gears instead of the shaft.

[R.C.]

Originally Posted by Trent B

Neutrino remade the shaft in mild steel as well as in stainless (I think 300 series). Both still had significant wear from the balls.

We are thinking of making a hardened tool steel shaft for off seasons, but that may just transfer the wear to the gears instead of the shaft.

The solution for us was to make the shaft out of 4340 steel and harden it to 50c. Never had to change it after that.

[Joe G.]

Versadog:

The metal bosses of the versakey pattern were REALLY tight in the vexpro gears. Almost unusably so, especially since we only used the versadog as a lathe jig, to allow us to bore out gears without using a 4 jaw chuck, and needed to remove the gear afterwords.

Solenoids/Solenoid manifolds

Extremely useful. Glad that these are available from a mainstream FRC supplier.

Dog Shifters

High quality stuff, but there needs to be a better way to purchase individual components of the dog shift system. There was no way for us to buy the shifting pins used without shelling out $75 for a PTO addon kit at minimum.

Versaplanetary dual stage input

It was not made clear on the website that this part did not provide support to the AM 9015 motors, as the normal versaplanetary does. Additionally, the two screws that hold the dual stage input together did not seem adequate, as the case warped and split open to some degree. Additional screws in the corners would have given it much more rigidity.

Belt pulleys

High quality stuff. 2x wide pulleys for 15mm belts would be appreciated, but what was made avaliable this year was very good.

[Trent B]

Originally Posted by R.C.

The solution for us was to make the shaft out of 4340 steel and harden it to 50c. Never had to change it after that.

Yeah, I was gonna suggest they make one out of 4340 or tool steel, something that is easy to harden heavily. Makes me think of the plates we were making to hold back the gas shocks last year, I think I had some of those parts upwards of 60C.

[Dunngeon]

Originally Posted by Trent B

Neutrino remade the shaft in mild steel as well as in stainless (I think 300 series). Both still had significant wear from the balls.

We are thinking of making a hardened tool steel shaft for off seasons, but that may just transfer the wear to the gears instead of the shaft.

I know Team Mean Machine made a custom ball shifter this year with completely hardened components for their shooter. The previous steel shaft had been damaged by the bearings when under shift + high tension. I don't have any up close photos of the shifter, but it's what they used to winch the punch back.

[cbale2000]

3-CIM Ball Shifters:

• Worked flawlessly, no issues at all during competition
• Shifts great, even when stopped or under load
• Changing out the shift spread was a bit of a pain since the small "C-clips" on the shifter shaft had to be removed before being able to take the old spread out (glad we did this between events and not during one).
• Face-mounting the gearbox with the 3rd stage required us to make some custom hollow hex spacers to allow us to attach the gearbox at the top in addition to bottom (we ended up just cutting some AM Churro to the right length but it would have been nice if something had been included).

VexPro Gears:

• We used Vexpro gears extensively this year in our drive system, and we never had to do maintenance on it all season.
• After 3 events and cleaning off a big of dirt, they still look brand new.

VersaPlanetary Gearboxes (with 1/2in Hex Output):

• Small, light, worked great.
• Adapting them to work with CIMs/MiniCIMs is a bit of a pain, I hope VEX comes up with a good solution because these gearboxes really do work great with those motors.
• I was disappointed when THIS happened during a motor replacement.

4" Traction Wheels (1.5" wide config):

• Great weight savings, especially compared to AM performance wheels we've used in the past.
• The adjustable width is a great feature
• It's difficult to find pop rivets that are long enough and have large enough heads to attach the tread.
• The 1.5" wide VexPro traction tread came a little over-sized and had to be cut down to be useable on the wheels.
• The VersaKey/Hub system worked great! It even allowed the wheels to drive when all the screws had come out of the gears powering them (we forgot to loctite).

BAG Motors:

• Pretty powerful for such a small package
• DO NOT let them stall, even for a moment, they WILL burn out (they do make an interesting "Burnt Marshmallow" smell though). We replaced about 3 of them on our shooters "Choo Choo" before swapping out to the more powerful RS775 motor.
• Cooling fans are a must for these if under heavy use, they can get "burn your hand" hot if you're not careful.

This was our first year using VexPro products and I will say overall I am very impressed by the quality of their products. Will definitely be coming back next year.

[Travis Hoffman]

10:1 VersaPlanetary + BAG Motor

Used the original VP with a welded polycord belt clutch drive (belt slips when ball acquired) in our roller claw. Didn't even have to attend to it once all year.

VEXPro Hex Shaft

Worked very well - held up all season in our drivetrain - very easy to swap wheels - no need to file the shafts to fit.

WCP Colson Wheel Hubs

Used four 4" dia. Colson wheels on the corner shafts of our 6WD West Coast setup. Hubs were bulletproof and Colsons barely wore down. Paired with 2 4" dia. custom 1.5" wide performance wheels with blue nitrile on the center shafts, had zero issues laying down defense or setting hard picks, and we maintained supreme maneuverability in high gear.

WCP 3-CIM WCD Dual Speed Shifters

Due to the initially confusing assembly instructions (which I expect will improve), it took longer to put these together than I would have liked, but once assembled, dry-lubed, and installed, these were just as bulletproof as the AndyMark offerings - it's good to have so many quality suppliers! This was the first year running a 6-CIM drivetrain, and these gearboxes put the power to the ground without a peep.

I will say that at least one of the sideplates had motor mount double holes that didn't exactly line up with the CIM holes. It took some coercion to get the CIM's to mount right. We put these on the practice bot. No issues, but not exactly comforting.

The plastic couplers used to mate the shifter cylinder to the dog shifting rod could also use some work to mesh all components together more happily. Hard to fit everything together and get the coupler screws screwed down properly, even when following the instructions.

[M. Mellott]

VEXPro Hex Shafts

Worked very well--no issues, and NO FILING!

3-CIM Ball Shifters

First time using a non-dog-gear-shifting transmission. They went together very easily. We used the outer plate to face mount the assembly to the inside of our 2x1 base frame, and then mounted a 35S double sprocket between the two aluminum plates. Due to the lack of space, we had to get creative and make our own spacers for between the transmission case and outer WCD plate. The mount never budged all season, but it would have been nice to have spacers included that could have been sized for a double sprocket, or extra-long ones that could be cut to length. As mentioned in another post, I didn't understand the non-symmetric mounting holes--this needs to be changed.

Overall performance-wise, we never had an issue. As the lowest-costing of the WCD 3-CIM transmission options, I'll definitely look to them as an option for next year.

10:1 VersaPlanetary + 1/2in Hex Output + BAG Motor

Small, light, solid, 1/2 hex shaft--love 'em.

With everything made of quality material, though, they need to have the motor plates made out of something more durable than plastic. The BAG Motor was tapped during some rough defense against us, and the plastic motor plate shattered, shearing off the motor and bending the BAG output shaft. I would also like to be able to buy that replacement motor mounting plate without having to buy 3 others that I don't need.

[Jared]

Aluminum Gears
We saw little to no wear on all our gears on our final transmission. I'm not sure why the bearing pocket on the dog gears doesn't let the bearing go all the way through. We noticed wear because the bearing and the gear had some slop and could wiggle a little. We got rid of this problem by cutting the dog pockets and a bearing bore that went .250 into the gear so that the bearing was more centered on the gear.

Having the .500 hex in the gear is really useful, as well as the little hub around it that is smaller than the diameter of the inner race of the bearings, which removes the need for a little spacer.

#25 Chain and Sprockets
The aluminum sprockets were surprisingly strong and showed no wear after many hours of practice driving. The #25 chain seems to be a little different from normal chain. The pitch is still .250, but it seems to be a bit stronger, and requires a "Heavy Duty" master link.

Shafts
The .500 aluminum hex shaft is the perfect size to fit into vex pro hex bearings and gears. It's a sloppy fit with the andymark gears and hex bearings, which we measured to be .512. We purchased the longer length of the shaft (maybe 18" ?), and it wasn't at all straight. We ended up not using most of the shaft and just taking the straight sections.

Bearings
They're all very cheap, but the hex bearings aren't as perfect as the round ones. They don't spin as freely, and they aren't all perfectly concentric. Some are a lot better than others. They work, but when possible, we plan on turning down the shaft and using a round bearing so that we can get a tighter fit.

Shifting Dog
We didn't use one this year, but we love the design. The part with the 4-40 threaded hole is thicker, which should make the dog stronger. We didn't use vex pro's dog, and our failure was cracking at the threaded hole.

[Oblarg]

WCP 3CIM SS Gearbox:

Almost a great product, but unlike AndyMark gearboxes it did not ship with loctited bolts to hold the CIMs on, and the access to the bolts holding on the bottom two CIMs was terrible (unless you took the gearbox apart, but that wasn't feasible on our robot). Combination of these two factors meant that we had a couple of bolts walk out, hindering our drive for a couple matches and forcing us to spend an ungodly amount of time trying to get the bolt back in place (we ultimately had to cut the end off of an allen wrench specifically to service the gearboxes).

I realize part of this was user error, but it's something that could be improved, regardless.

[T^2]

Originally Posted by Oblarg

WCP 3CIM SS Gearbox:

Almost a great product, but unlike AndyMark gearboxes it did not ship with loctited bolts to hold the CIMs on, and the access to the bolts holding on the bottom two CIMs was terrible (unless you took the gearbox apart, but that wasn't feasible on our robot). Combination of these two factors meant that we had a couple of bolts walk out, hindering our drive for a couple matches and forcing us to spend an ungodly amount of time trying to get the bolt back in place (we ultimately had to cut the end off of an allen wrench specifically to service the gearboxes).

I realize part of this was user error, but it's something that could be improved, regardless.

I believe all VEXPro products, including those under WCP, require the user to provide Loctite when specified.