VEXPro 2014: After The Season

[T^2]

You know the drill.


3-CIM Ball Shifter

This product was a bit of a mixed bag, but the upsides outnumbered the downsides. The gearbox is light, generally reliable, and has a good variety of speed options. We used ours in a WCD with WCProducts bearing blocks, and once the drivetrain was together, we never had a problem with it. We were fast in high gear, pushy in low gear, and only once had to run maintenance on the gearboxes themselves (see next paragraph). Definitely a solid choice for teams wishing to save time on custom gearboxes. I maintain my stance that the ballshift mechanism is both faster and more robust than shifting with dogs.

Most, but not all, of the problems we encountered with these gearboxes arose from user error. Notably, the mounting nuts on the sides (or rather, the top and bottom, when mounted with the stock 3rd-stage plate we used) are not meant for high loads, and will tear through the shell if used in that manner. We found two significant problems that are, I feel, an inherent part of the design. First, the stock 3rd-stage mounting plate's holes for mounting to the frame (of a WCD, in our case) are asymmetric: one is horizontally 1.976 inches from the 3rd-stage output, and the other is 2.024 inches horizontally from the same. This is compensated for by an increase in the hole size. I cannot possibly imagine why the holes could not be symmetric.

The second issue, which is a bit more important, is that the gearbox feels as though it is not designed with a west coast drive in mind. Attaching a WCP center bearing block to the system requires using low-profile 10-32 nuts on the inside of the plate, which are difficult to access with chain in the way. (There might be a better way to do this, but I can't find any documents that say so.) Furthermore, the 3rd-stage shaft runs through two bearings that insert in the same direction: one is a press-fit into the nylon shell, and the other is a slip-fit into the bearing block. If the press-fit fails, as it did for all four of our gearboxes, then the entire output shaft assembly will partially slide out of the robot until about half of the output gear is in mesh. To solve this, we had to Loctite the outside bearing into the bearing block. I'd really rather not.

Speaking of Loctite, this year's ballshift shaft assemblies are an improvement over last year's. We noticed no issue with the shaft coming out of the housing, unlike last year. However, this wasn't the case with all teams; at Champs, I helped another team perform an emergency Loctite replacement on one of their drive gearboxes because the shaft had extracted itself. Overall, I can say that while a better job was done this year with regards to Loctite application, I still wish for a mechanical connection between the shaft and its housing.

Last note: while we didn't use it ourselves, multiple teams with whom I spoke were satisfied with the new plastic encoder gear.


VersaPlanetary Gearbox

The advantages to these are the same as last year; I'll focus on the problems with the new stuff. The 7:1 gear stages we ordered had weak welds, which cracked in short order. I'm sure this will get fixed soon. The main problem we experienced this year was with the new plastic motor mounting plates. While a step up from last year's system, the plates were difficult to attach to the gearboxes because their mounting holes had extremely thin walls around them; tightening the mounting screws just a bit too much led to fracturing. Please either make these out of aluminum, or improve the wall thickness. (Doing both would be best; one of the secondary disadvantages of the plastic plates is their poor rate of heat flow for purposes of motor cooling.)

We found out the hard way that these gearboxes are not meant to take heavy loads while powered by MiniCIMs. They're great for intakes, though.

WCP Cam

Amazing. I wish the hex shaft on the steel model could be a bit longer, though.


Wish List

A 17t #25 sprocket option, for chain-in-tube drives.
A stock butterfly module, paired with a stock frame that can use it.
A hall-effect sensor magnet with the same center hole, but a smaller outer diameter.


That's about it for what 1678 used. If anyone could elaborate on the quality of the VersaWheel DT, the dual-input VersaPlanetary, or the plastic pulleys, that'd be great.

[MichaelBick]

Originally Posted by T^2

A 17t #25 sprocket option, for chain-in-tube drives.

We ran chain in tube for our intake this year, and it was a very unpleasant experience. Maintenance is an issue, and you have to be wary of where you place fasteners. A drive would likely be less maintenance than an intake(because it was running significantly faster), and I know that 118 has run a chain in tube drive successfully, however personally in the future I would only consider running belts in tube.

[cadandcookies]

Versawheel DT wheels (4" bearing bore) were awesome. We ran them for two regionals and experienced minimal wear. Cheap, effective, and frankly better than any wheel we've used before (that being said, the team hasn't ever used Colsons).

We also used VexPro VersaPulleys, which were absolutely fantastic. I don't think we had a single failure, and they interfaced very nicely with the VersaWheel DTs to make a drive train that didn't break once during competition.

I think 2220 will be using VexPro products for years to come...

[Boe]

3 CIM Ball Shifters:
We had an amazing experience using these after we finally got them, they were light ran great, and had lots of options available.

Versaplaneteries:
My favorite product this year the amount of different stages and motor combinations is insane. I would also like to see the motor mount plate be aluminum if possible.

3.25 Wheels:
We decided to go with these over our usual blue nitrile wheels in the build season, but after getting them on the robot and driving them we really did not like how quickly they wore and didnt feel they gave enough traction compared to the blue stuff. We ended up switching to AM Performance wheels in the last week of build.


New product wishlist:
All in one options for wheels with hex built in. I would absolutely love to see all the vex wheels have a one piece hex option so the hubs are not required thus reducing part count.

[DampRobot]

VEX Pro 3 CIM Ball Shifters

I had a more mixed experience than T^2 with the ball shifters.

First, I didn't find them as nearly easy to maintain as he did. I consider myself pretty good at figuring out how stuff goes together, and pretty good at fixing things, but I found these gearboxes a bear to maintain. It took two pretty smart guys two full days with my help (and the instructions) to assemble these gearboxes. I don't remember other gearboxes taking so long to go together. A lot of it is there are a lot of different fasteners that need to go into the gearbox, and another big part is that things have go together in a very specific, non-obvious way. If you put it together wrong, you suddenly have to take the whole thing apart again, all because you forgot to put a tiny nut into the inside of the casing in step 7.

Also, they fell apart on us a lot. Over the course of the season, the screws inside of the casing that hold on the encoders or pancakes worked their way out. We had to fix each several times over the course of the season, despite loctiting and tightening as much as possible. It wouldn't be that big of a deal on an open gearbox, except you have to take the whole darn thing apart to get to those two tiny screws because it's a closed gearbox. Also, they're pretty sensitive to the screws holding the case together being overtighened. I remember having to rebuild one side of our comp drivetrain on ship day because it was binding. Turned out that one of the screws holding the casing together was just a tad overtightened, which killed our efficiency on one side of the drivetrain.

The ball shifting is nice. I like it. I wish the shifter cone was a bit nicer, maybe metal like the WCP ones used to be instead of the two side plastic casing it is now.

I liked having a lot of ratio options, and the quality of the gears was very good.

I agree, this gearbox really isn't designed around WCDs.

I'm advising my team next year to go with the 2 CIM DSes. They're a lot smaller, we haven't had reliability problems with them in the past, and they're a ton easier to service. Finally, they're really designed to do a WCD, instead of adapted to work for it.

VersaPlanetaries

This is probably one of the best products ever to hit the FRC market. It's a planetary that just works, and has a ton of options. It's really revolutionized how we build manipulators. I especially love the dual input VersaPlanetary, it's an awesome way to build a crazy powerful arm/whatever really simply.

Pulleys and Belts

Like a lot of teams, we had problems with snapping the belts. I believe this is a MFG issue (and if so, something VP NEEDS to fix), but if it isn't I at least hope were told better load rating specs for these belts. We shouldn't have to worry about belts snapping in something as critical as the drivetrain.

Other than that, it was nice to have hex broached pulleys and an easy way to get belts and pulleys.

VersaWheels

I have mixed feelings. It's nice to be able to replace wheels instead of retreading them (because dealing with tread is a PITA). The wheels have a really great traction right out of the box. On the other hand, they wear extremely quickly, to the point where if we had the supplies, I'd want us to change them out every three matches or so. Also, once they're worn, they have essentially no sideways traction, so they absolutely suck once you get T-boned (thanks 971!). The DTs wear slower and have better sideways traction, but don't have as much forward traction as a new VersaWheel OG.

I'm going to tell my team to do blue nitrile wheels again next year. They are a pain to tread, but don't wear as quick, and have grip to spare.

Hex Spacers

Who knew such a dinky little product could become so useful? I essentially never design in spacers now, I just trust the kids to find the right combo of spacers/VP hex shaft collars to work without any custom design/lathe work.

CAMs

Are the bomb.

[Aren Siekmeier]

VersaWheel DT (3.25 Hex Bore)

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

HTD Belts and Pulleys

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

VersaPlanetary Gearbox

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

3-CIM Ball Shifter

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

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

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

-----------

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

[electroken]

Originally Posted by compwiztobe

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

This happened to us too, and it cost us some autonomous points until we figured out what had gone wrong.

[Aren_Hill]

Originally Posted by electroken

This happened to us too, and it cost us some autonomous points until we figured out what had gone wrong.

One option you had was to Email me and I would've sent a set with a much tighter press to you free of charge, since you ordered the gearbox.


-Aren

[aldaeron]

All the stuff we used was great as has already been praised for its ease of use.

I am hoping for an earlier release for new parts to allow some time pre-season to test parts (September release instead of December). Maybe even a raffle for teams to beta test (free testing and marketing!)???

What I am most interested to know is whether or not there will be a new VEX motor controller this year? Perhaps even a dual or triple motor controller (one unit with a single PWM input and three input/output pairs so that 1 controller is used for 1 transmission). I realize carrying single, double and triple motor controllers is an inventory nightmare, but perhaps there will be a clever modular motor controller design to allow efficient packing and heatsinking of multiple motor controllers. As FRC keeps allowing more and more actuators, getting all the controllers laid out becomes a non trivial problem.

Keep up the great work!

-matto-

[Adam Freeman]

This year we used numerous VEX Pro products on our robot.

3CIM Ball Shifter: We ran them for 4 events with 3 CIMs and at Champs with 2CIM + 1 miniCIM. We were able to swap in miniCIMs on Wednesday of Champs with no issues. We actually shifted the ball shifters this season with pancake cylinders (I believe supplied from 2013 2CIM Ball Shifters). No issues with reliability or durability. We did have to request the tighter press encoder gears, b/c the original equipment encoder gears were slipping on all (4) of our gearboxes (practice and competition). In my opinion the lightweight, gearing options, and ease of maintenence will make these our gearbox of choice heading into 2015.

Versaplanetary Gearboxs: We ran (5) VP planetary gearboxes. (2) @ 100:1 on the shooter angle adjustment w/RS775, (2) @ 5:1 on the shooter pull back carriage w/RS775, and (1) on the intake at 10:1 w/BAG motor. These are my favorite utility gearboxes offered on the market. Outside some hole alignment issues we already coomunicated to VEX Pro, the only issues we had were the pins on the 10:1 gearboxes walking out of their holes. We had to pull the gearboxes once/event and put in new 10:1 plates with the pins locktited and re-pressed into the holes. These were always the highest loaded stage in the gearbox (last stage before the motor?). I assume we are overloading the 10:1 plates at that stage through the amount of usage we put on that shooter arm.

Various belts and pulleys: Drivetrain was 100% VP 24T and 42T pulleys. Originally started with 9mm belts all around. Prior to competition season we switched to McMaster Kevlar re-enforced 15mm belts on the center wheels. All belt lengths were calculated using the WCP belt calculator. During practice we were getting some belt rachetting and snapped one 9mm belt after a wheel change. We couldn't determine exactly why the belt snapped, but felt more comfortable switching to the wider re-enforced belts. Overall we were extremely happy with the drivetrain performance over our traditional chain drive, and will probably be running a similar setup next year.

Intake was also run with VP belts and pulleys (18, 24, & 30T pulleys). Our intake took a major beating and never once did we have any issues with driving the intake or alignment of the belts or pulleys. Needless to say, I am a fan of more belt and pulley options.

VersaWheels and Hubs: We started with 4" Versa DTs all around on an 8WD chassis. We were not getting the turning performance we wanted during practice and testing, so we switched to the W pattern wheels on the inner 4 to reduce the lateral friction, while keeping good fore-aft traction. We got about a 1.5 competitions/wheel set on the Ws. They were worn down pretty far, but we are happy with the performance to wear characteristics of these wheels. The DTs seemed to appear worn quite a bit faster but still held decent subjective performance. Overall the VersaHub system made setup and wheel swapping very easy for us.

We might be channelling our inner Killer Bee and trying some 4" omnis on our drive this summer. I'm sure they will be just as easy to swap in.

Overall we are very happy with the quality of products, ease of ordering, purchasing, service, etc. available from VEXPro this season.

I'd personally love to see a servo, motor, or electric actuator setup for the ball shifters for years we aren't using pneumatics, but I'm not sure we haven't switched to the dark side from now on. Obviously not an easy thing to do, or they would have already done it.

Keep up the great work!

-Adam

[BrendanB]

Originally Posted by Adam Freeman

Versaplanetary Gearboxs: We ran (5) VP planetary gearboxes. (2) @ 100:1 on the shooter angle adjustment w/RS775, (2) @ 5:1 on the shooter pull back carriage w/RS775, and (1) on the intake at 10:1 w/BAG motor. These are my favorite utility gearboxes offered on the market. Outside some hole alignment issues we already coomunicated to VEX Pro, the only issues we had were the pins on the 10:1 gearboxes walking out of their holes. We had to pull the gearboxes once/event and put in new 10:1 plates with the pins locktited and re-pressed into the holes. These were always the highest loaded stage in the gearbox (last stage before the motor?). I assume we are overloading the 10:1 plates at that stage through the amount of usage we put on that shooter arm.

I forgot to mention in my post but we too experienced problems with our 10:1 stacks with the pins coming out on our 100:1, 10:1, and 40:1 gearboxes (pickup pivot, shooter winch, and pickup roller). Our original thought was they were from last years batch as we inventoried our supply and ordered what we needed as it was cheaper than buying all new complete gearboxes so we thought it was our fault either in testing, storage, or something else. We ordered all new 10:1 stacks between our first and second district events and haven't had an issue since.

It could be how we used them but it happened on our 40:1 pickup roller which I don't believe we ever stalled or abused in a match.

[Travis Hoffman]

Anyone want to take a stab designing an "electric cylinder" linear actuator product compatible with FIRST-legal motors and made with lightweight yet strong materials?

http://www.nookindustries.com/Produc...FeY-MgodlDMAZw

[nuclearnerd]

Originally Posted by Travis Hoffman

Anyone want to take a stab designing an "electric cylinder" linear actuator product compatible with FIRST-legal motors and made with lightweight yet strong materials?

Princess Auto is a popular auto parts and surplus store in Canada. They sell a Chinese brand of electric cylinder (complete with limit switches and potentiomenter feedback!). I picked one up at the beginning of the season, but we never modified it to use FRC legal motors because our design didn't end up needing one. One unanswered question was whether we could speed up the (really slow as stock) extension speed:
http://www.princessauto.com/pal/en/E...ator/8272551.p

[Thad House]

We used a lot of VexPro parts this year.

WCP 3 CIM SS WCD
We used them this year, and absolutely loved them. They were reliable, easy to assemble, and easy to mount and remove from the robot, which we had to do multiple times because of belts. They were light, strong, and in general out of the way of the rest of our robot. The only problem with them is that the flanges for the bearing on the main shaft both face the same way, so if the press fit fails, the shaft moves. So please flip the bearing on the back plate and include spacers the correct length so the flange can go on the outside. We fixed that this year by screwing bolts with washers over the flange on the inside, but for next year that would be a great fix. And, even though its not provisioned for it, there was an easy way to mount E4P encoders using just some 3d printed parts and the cutouts in the plate. The only issue we had was them not showing up until week 4.

1/2 Hex Shaft
Love it. Used it on our drive. Never failed once. 'Nuff said.

4" VersaWheels W & DT
We used both on our robot this year. We used the W's in the center, and DT's on the outsides. We have some mixed feelings about them. They wore down really fast, and we were replacing them once an event. They were noticeably loosing sideways grip the later in the event they got. By the end of Galileo finals, one of our DT's was starting to bubble, and another was cracked down the side where it meets the tread. But when fresh, they had tons of grip.

VersaPlanetaries
We used them for the first time this year, and overall we had a good experience with them. We originally had the 7:1 and 9:1 sets, but then they started cracking, and we moved to the smaller reductions. We had issues a few times with screws coming loose, but mostly we just have to make sure to loctite better. One suggestion is to fix the pricing. Buying the gearbox with 3/8" Hex output is $29.99. Buying the 1/2" Hex shaft is $7.99. So why does the one with the 1/2" hex already installed cost $39.99. It just doesnt make sense, and we actually bought the 3/8 and then installed the 1/2 inch to save the money and get more at the same time. Because we did this, we had the snap ring come off of the practice bot, because we could not get the snap ring in right.

Belts
Ah belts. This year we had 6 CIM's. We used 24t 9mm pulleys with 130t belts. We snapped 6 of them over the course of the year. I heard that next year there is going to be a 27t pulley, and the belts are going to be much stronger, which is why I'm not going to worry too much. But please for the belts publish the torque ratings of the belts so we can do the calculations. We switched to using 18t sprockets and #25 chain at worlds, and had no problem whatsoever with it. But if the belts next year are stronger, and we can get bigger pulleys that will fit a WCD we will go back because we loved the students.

Overall, we liked most of the VexPro stuff we used this year. But I do have some suggestions for improvements.

• Sell the WCP DS with the 3 CIM SS plates. I know they have the exact spacing, so it should be easy. Or sell all the pieces individually so teams can mix and match.
• If you are going to sell something for the season, make sure it is in stock at the beginning, and not at week 4.
• A 27 tooth and a 47 tooth gearset for the WCP SS gearboxes. We wanted 10.5 FPS, but to get that, we had to use 14t pinions, which again showed up really late. with a 27-47 we could have used a 12t and gotten very similar to the same ratio.

[Samwaldo]

Single Reduction, Single speed gearbox (7:1)
6 CIMS!!! Overall an extremely simple gearbox that was quite reliable and did its job better than we thought. We became known for our drivetrain and won an Engineering Excellence award for it. Were glad we bought 2 extras, and never needed them.
Our only problems/complaints: 1) cover the sides of the gearbox. We created our own covers so that stuff wouldnt get into the exposed gearboxes 2) The hex collar would occasionally slip which would create slop but we could still drive with the gearboxes

Overall easy to deal with and they gained new customers from us.