VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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...

Re: VEXPro 2014: After The Season
 

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 ::ouch::

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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 :D. 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

Re: VEXPro 2014: After The Season
 

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.)

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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

Re: VEXPro 2014: After The Season
 

Hi all, thanks for the constructive feedback posted thus far in the thread.

Last year, VEXpro released a survey looking for customer feedback from the 2013 season. That feedback directly influenced our product development / improvement processes for the 2014 launch, and we'd like to reach out to the community once more now that you've had even more time to play with our products.

Please visit the form here:
https://docs.google.com/forms/d/1-iP...PUw14/viewform

Of course, feel free to share this link with other teams, team leaders, etc. We'll see you again next year!

Re: VEXPro 2014: After The Season
 

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

Re: VEXPro 2014: After The Season
 

Thank you for providing a direct line of input for the community to provide feedback. It's been great seeing the VexPro line introduced and improved for the last two years.

Re: VEXPro 2014: After The Season
 

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

Re: VEXPro 2014: After The Season
 

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-

Re: VEXPro 2014: After The Season
 

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

Re: VEXPro 2014: After The Season
 

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.

Re: VEXPro 2014: After The Season
 

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

Re: VEXPro 2014: After The Season
 

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

Re: VEXPro 2014: After The Season
 

2 more suggestions, and they are both about CAD.
1. Make the parts default to standard, not metric. Since the parts are made in standard, all the metric dimensions get really weird. I know this would be hard to change for all the current stuff, but maybe next time.
2. Fix the hexes. Maybe this is something only I do, but usually I like constraining hex shaft to the hex bores. For some reason, the hex bores in all the VexPro parts are all over the place in dimensions, so it is next to impossible to directly constrain hexes.

Re: VEXPro 2014: After The Season
 

This is probably because the nominal size of the hexes varies. For example, I'm pretty sure the bearing fits are .500", the gears, sprockets, and pulleys are about .502" nominal, and the spacers are probably a bit larger than that.

I'd rather have the VP CADs be the correct size. I like hexed things based on features concentric to the shaft (like the hub OD) and then make one part of the hex on each of the two parts parallel rather than making two parts in each of the hexes coincident.

Re: VEXPro 2014: After The Season
 

This is correct. Knowing that the shaft is, say, .497, and the bore .503, is important for certain design considerations. As Damp mentioned, using angular/parallel constraints is just fine.

Also, I agree that the CAD files should all be imperial. Sometimes, I get constraint failures when trying to attach, for example, a metric hub to an imperial wheel, due to dimensional differences that result from the two standards.

Re: VEXPro 2014: After The Season
 

Versaplanetary Gearboxes: We use them all the time. They are awesome for prototyping and iterating designs. The two 10:1s with bag motors on our intake had no issues all year. The 50:1 for shooter angle did have the pins back out a few times on the 10:1 stage, but we were running our entire arm off a cim into a planetary. If that's the only thing that goes wrong, I'm impressed.

VersaWheels and Hubs: No issues here either, though the VEX tread was quite soft. We wore through the rubber after our first competition.

Gears and Sprockets: Both show minimal wear, even after 5 competitions. We had a wheel try to eat the aluminum part of a field door, and the sprocket still looked fine.

Re: VEXPro 2014: After The Season
 

vex 3 cim gearbox
the pressfit gear for the encoder started to wear out after 1 competition on our comp bot so the press fit would slip affecting our autonomous driving and we had a field day trying to figure out what the problem was
vex 2 cim gearbox
we used 1 for our catapult pull back we know it was not meant for the load that it experienced but the little bearing and c clips on the shifter shaft kept breaking i'd like to a different type of system used for the bearings

Re: VEXPro 2014: After The Season
 

I found a production product using a versa planetary.
http://novakon.net/parts-store/bedmills/pdb-torus-pro/

https://www.youtube.com/watch?v=LFkS3cvaeUI#t=424

Re: VEXPro 2014: After The Season
 

There shouldn't be any problems due to differences in measurements, because inches are actually a derived unit from metric.

Re: VEXPro 2014: After The Season
 

You're right; I had a total brain fart there. Any ideas why I can't align a VersaHub (live axle .5hex) mounting pattern with the pattern on the 4in omni wheel?

Re: VEXPro 2014: After The Season
 

Yeah, I've noticed this problem a lot. On the versahubs (I think) the mounting hole pattern is 0.9376" radius instead of 0.9375". It makes mating these things to custon versakey stuff nearly impossible, because other versa products are just 0.9375" radius.

Re: VEXPro 2014: After The Season
 

Those issues were the same issues as I was talking about with the hexes. You can constain to the axes of the circles, but trying to constrain any further then that is impossible because the dimensions are slightly different. CAD doesn't like being off by .001.

Re: VEXPro 2014: After The Season
 

Just a question (does not necessarily belong in this thread). We have never tested this, but how much psi does the stock (0.75" bore) piston require as a minimum for reliable shifting (on the fly and stopped) on the ballshifter? We always ran ours at 60psi, but how low could we have gone?

Re: VEXPro 2014: After The Season
 

We found issues shifting reliably when we went under 30 PSI.

Re: VEXPro 2014: After The Season
 

A rule of thumb minimum I've heard is 40psi for shifting. Saves a decent amount of air volume and still gets the job done.

Re: VEXPro 2014: After The Season
 

I believe you aren't able to shift because the VEX solenoid valves are not entirely actuated by electromagnets, they by require ~30 PSI (iirc) to trigger properly. Someone from VEX should be able to verify/refute this.

Re: VEXPro 2014: After The Season
 

Maybe, but you could hear the cylinder engage and the driver could feel it trying to get in gear. It doesn't really matter anyway, shifting under 40 psi is more than I would expect from a shifter. We were able to get through a match with 2 black clippard tanks charged to 60 psi.

Re: VEXPro 2014: After The Season
 

Unfortunately, if the solenoid is the known limiting factor in the shifting, it does not help me much.

I had an idea for an electric shifter, and less force means faster, so delivering 14lbs of force (0.75" bore piston at 30psi) is much more ideal than 28lbs (60psi equiv), if it does the same job but quicker.

Re: VEXPro 2014: After The Season
 

Update!!!

3 CIM Single Speed, Single Reduction gearbox (7:1)
After 2 Districts, 1 District Championship, 1 six hour demo, and hours of drive practice, one of our drive axles snapped clean in half

Details:
We have become known in the NE and specifically CT area for our drivetrain. At the Groton District Event we even recieved the Engineering Excellence award for it. We give credit mostly to these wonderful, simple, and great looking gearboxes. Our defensive play became a force to fear! We could push almost anyone which put alot of stress on the gearbox.
Our setup is our own custom drivetrain. Tank drive, with 1/16 drop. Six 4 inch HiGrip wheels that are ran by belts . The belt that transfers all motion from the transmission axle has a tensioner. Their are many other things that put us above others but it isnt too important to this.
After awhile we noticed slop in the gearboxes, so we added some extra bolts, tightened some axle collars, and added belt tentioners. This eliminated most slop but there was still some in the transmission axles. We went like this for 1 1/2 more districts, demos, and drivers practice.
Finally at CT State Championships after 4 matches our new driver lost all control to the right side. It was discover the axle could spin freely by hand. After opening it up and finding a broken axle, our day was over. No one had any spare gearboxes. With no choices, we had a barbeque in the parking lot and could no longer compete. (The barbeque was a blast and no one was that upset about dropping out due to the team bonding)


The gearbox was overall fantastic but I hope no one else ran into this problem. This problem ended my last competition as a student a bit too shortly :(

Re: VEXPro 2014: After The Season
 

You couldn't machine a new one? It's a pretty simple part to make.

Re: VEXPro 2014: After The Season
 

CT State Championships, had pit sizes of 6 X 8 . Due to this smaller size everyone brought very limited parts. Mostly just basic tools. Also it did have some parts to it that would require more machining like a lathe which this venue didnt have.

Re: VEXPro 2014: After The Season
 

Did it fail at e-clip groove?

Re: VEXPro 2014: After The Season
 

Do you have photos? We have just used hex shaft in those gearboxes with out any issues. No custom machining needed, did you do custom work after to make it work in your robot? We just added a 2nd shaft collar to lock everything in place and swapped the rear bearing to a hex bearing.

Re: VEXPro 2014: After The Season
 

To be honest I didnt look to closely, but it did seem like it broke in a groove. Basically a weak point. I do know it was in a part of the axle that was 1/2 inch.

Edit: I will see if we can find it, to take pictures of. No changes except putting a pulley with set screws on the hub at the end of the axle for the belts which added more pressure to the axle due to how far it was placed.

Re: VEXPro 2014: After The Season
 

Same thing happened to us at CMP last year, we discovered that one of the internal bearings can work it's way loose and cause the cantilevered output shaft to put force directly on this groove. It's for this reason that we recommend using either the WCP single stage, or a custom gearbox

Re: VEXPro 2014: After The Season
 

On a different note - it seems like VEX does not have a lot of their items in stock right now. Most notably items that fit with the 3 CIM Ball Shifter.

Is there a production problem, or will we be expecting upgrades that would make the latest rendition obsolete?

Our team is looking to order a certain configuration for off-season training and development, but we don't wish to commit until the items are in stock.

Thank you.

Re: VEXPro 2014: After The Season
 

With this type of thing, it's probably best to email VP directly. I'd suspect that if they are listing items as out of stock, they aren't in VP's warehouse and are being reordered, but I'm sure you'll get a lot better information out of them than me.

You can also check WCP, they might have some 3 CIM Ball Shifters in stock. Alternately, you can see if a WCP DS (if they're in stock) fits the bill.

Re: VEXPro 2014: After The Season
 

I'm a bit new to all the nuisances of drivetrains, but these statements seem almost contradictory to me. A 7:1 ratio on 4 inch wheels should give you somewhere in the ballpark of 14 ft/s (less when loaded). How were you able to push so effectively with such a low gear ratio?

Re: VEXPro 2014: After The Season
 

As the driver, I can tell you a few things that put us above others, drive train wise (other than my 3 1/2 years of experience)
- 6 CIMs
- 1/16 drop instead of 1/8
- belts very tight and tentioned
- within a pound of 120lb (without bumpers and battery)
- due to how low our center of gravity is and little clearance our chassis couldnt be lifted up while pushing which kept all wheels on the ground.
-change wheels after comps in order to keept treads on them
- wheels pushed outwards as possible to increase support polyigon and stability. (Instead of a wheel inbetween 2 pulleys, 2 pulleys are side by side and then attached to one side of wheel, thus pushing each wheel 1 inch more outwards)

As a driver, 1 of my favorite memories this season included a 3 on 1 match. We were alone to score with 2 defensive bots on us. I ignored them and just pushed them with me the length of the field if they got infront of me. We won that match.

Overall we were very impressed by these gearboxes, and would like to give VexPro a huge thanks, for the hard work their putting in, to produce quality products. We will most likely be using these again but supporting the axle on the other side.

Re: VEXPro 2014: After The Season
 

We are in process of deciding which components we will be adding/updating based on feedback we received this year, some parts that are out of stock may be receiving updates, as always we aim to have any updates as backwards compatible as possible.

-Aren

Re: VEXPro 2014: After The Season
 

I looked at it briefly at the competition. It was broken at the e-clip groove.

Re: VEXPro 2014: After The Season
 

That is what I was afraid of. We went ahead and ordered the 3CIM ball shifter without the 54:30 option (hoping to add it at a later time). Well, at least the team will still be able to work it into our skateboard frame.

Thanks for the head up.

Re: VEXPro 2014: After The Season
 

Revisiting this: I have a little nitpick about the WCP cams.

AFAIK, the original design of these cams in traditional west coast drives was with a single smooth contour at a constant slope of 10 degrees (logarithmic spiral, nautilus cam, whatever you want to call it) with the slope selected so that it's tangent was less than the coefficient of static friction between the bearing block and the cam, and force applied by the bearing block (via chain tension) could not rotate the cam and chain center distance. Please correct me if I'm wrong about this.

The WCP/Vex cam added grooves along the contour. This idea seems to make sense: the rounded tip of the bearing block falls into the groove and can't hop out. Retreating the block still allows you to rotate the cam to adjust tension. However, the change in geometry means that the friction condition no longer holds (there is no longer a uniform slope along the entire contour), so the the block will always slide along the cam into the nearest valley. The problem is that this forces the chain center distance to be at the one these points, which are about .010 apart near the base of the cam and up to .025 apart at the tip. We'd really like to get our chain tension to within .005, and have noticed that despite proper tensioning before a match, tightened bolts, etc., certain chains would invariably become a little looser than others based on slight differences in where the cams are mounted near each wheel slot. I don't believe this ever caused any catastrophic failures, but it made us nervous, and I'm sure it also affected efficiency and wear.

Is this something other people have seen with these cams? Are we using them incorrectly?

Re: VEXPro 2014: After The Season
 

I'm surprised you need to keep your chain tension within .005; this seems excessively precise. We ran a WCD using these cams, and kept the chain (McMaster) slightly slack. We almost never had to tension them. Perhaps you're tightening the chain too much?

Re: VEXPro 2014: After The Season
 

I don't feel that having your center to center for a chain off by ten thousandths of an inch vs. five thousandths of an inch really does much. Chain doesn't have to be ridiculously tight. In fact, tight chain is bad for bearings and such, and has lots of friction filled rubbing. Running them on the loose side gets more efficiency.

If you did want superior adjustment, you could likely grind down the existing cam and edge of the bearing block into a smooth surface. The cam doesn't have to be a fancy shape, just something with a non constant radius.

Re: VEXPro 2014: After The Season
 

The design that 254 ran for years, and that we (and others) later copied has the clicks you describe.

Re: VEXPro 2014: After The Season
 

Perhaps it is excessive... Somehow my earlier measurements were bad, looks like the jump is uniformly about .010 all the way around (as one might expect due to the geometry). So one should always be within 0.005 anyway.

The chain should not be tight, but it should also not be hanging loose, rather it should be at length. But there is probably more variation due to sprocket rotation that causes transient chain sag. So I seem to be way off the mark.

This is sort of what I was wondering. Good to know.

I'm just paranoid.