2020-2022 COTS Reviews

Reviving the pre-pandemic trend of reviewing new COTS products (2018, 2019), what new products did your team use in this seasons and in the pandemic-impacted2020 and 2021 seasons? What changes did you have to make to get the desired behavior? What do you want the manufacturer to change about the product for future years? Would you recommend the product to other teams?

Note - there is a separate thread for the REV Control System specifically


Wago 221 inline connectors changed my life.


We used the new MAX planetaries this season, they were quite durable and changing the ratios is pretty nice when partially redid our climber. However, make sure to put lots of loctite when installing the hex shaft as that screw otherwise is annoying to get at. Highly recommend.

We also used sds modules for the first time this season, we used mk4s because we bought them before mk4is were released, the plates on the mk4s can bend so we will likely upgrade to mk4i/5i for future seasons. The outside flanges on the billet wheels also did receive damage from the cable protector. Otherwise, they held up very well Would recommend.


Greyt Telescope bearing kits - These were great and a huge savings of resources. We used the 1" to 1.5" and 1.5" to 2" kits with our own gearboxes. They took a little while to assemble but we had no issues so far. Put these through some abuse and they are holding up great.

WCP SS Flipped Gearboxes - WCP gearboxes are our go to and these were my personal favorite that we’ve used. Assembly was easy and I like the lack of snowman holes. We had a pretty big self induced failure involving shredded steel second stage gears but the swap out was probably as smooth as it could have been for the circumstances. This will mostly likely be our standard tank drive box in the future

McMaster turntable bearing #18635A52 - It’s our second year using it and we got a ton of questions about it. Haven’t had any hard impacts on our shooters in 2020 or 2022 but it’s held up to normal use great. It’s super easy to bolt this on using it’s tapped holes and quickly CNC a sprocket generated in Onshape or Solidworks


Highly recommend the Mk4i. Our team used them, they’re extremely durable and survived any falls we had from the bars throughout the season. Also we loved that they were relatively compact, it made us on the CAD team happy.




Curious what gear in the second stage shredded for you guys? I ask because we had catastrophic failure of our steel 16t 1/2" hex bore gears on the second stage of these gearboxes this year.

The gears completely split in half, causing us to miss matches each time it occurred. Looking at the gear, it seems no surprise these sheared in half with how thin the cross section is. We were shocked to realize such a gear was being used in this application, and are rethinking using them in future years as a result…

See also this thread regarding 16t gears in WCP SS gearboxes:

Thanks, missed this thread with all the excitement of DCMP this weekend!

3452 Used The Thrifty Bot Swerve and we’re happy with it. This is our second season using it but first season with actual matches. Like many others our first issue was with the tread. We used the black rubber tread that came with it, switched to blue nitrile but in the end it never sat flat in the wheel and we never quite mastered cutting it to size and adding screw holes to line up. Now if this is assembly error or just what the tread does I’m not too sure. However I would not consider this the fault of Thrifty Bot. Our solution was to print our own tread using TPU. It works great one set lasts an entire district event quals-playoffs. The option to switch where the encoders get mounted came in handy after having one of our encoders get broken in a match. This could have been avoided had we put some guarding on the bot earlier. We did have a fall off the transversal bar, only one module was damaged, suffered a bent main plate and a bent axle. I’m not too sure you can expect any model to survive that fall, I’m quite impressed with how little damage it did have. None of the printed parts were damaged, after 2 district events and FIM States I can say these modules have held up and have been very impressive.


Andymark Climber in a box was great. Helped simplify our traversal mechanism after modifying it to meet our needs.

The new Andymark 24t Pulley is also very nice. We used a few of these this year, but they ran out of stock before we could use them for all belting applications (there were several on our robot). The flange on these is very strong, and difficult to break. I like these over the Vex alternative…and these will probably be our go-to 24T pulley going forward. Maybe Andymark would consider making other sizes using the same method of holding the flange on? I would be a happy customer if they did.

The WCP Tubing plugs were awesome too. Our team prefers bolts to rivets, and this gave us a lot of new options to avoid gussets and make lower profile mechanisms. I think this will end up being a product we stock up on pre-season and can use as we need.


We are going to actively avoid buying from vex as much as possible in the future because of the widespread QC issues we have seen this year, and in the past. Rev is our new best friend


We used a 20 to 28. The 20 was missing all teeth and the 28 was missing about 4 teeth. It was caused by something getting lodged in our drive chain, popping it off, and sucking it into the gearbox. It was early into the match so our drive team decided to spend the next couple minutes trying to get to the hangar causing all kinds of carnage and required us to swap the whole drive rail.

New products we used on 2020 / 2021 / 2022 bots:
SDS Mk4i: Awesome, will be our standard swerve module for the future.

REV PDH and new breakers: The overly sensitive sticky fault on the PDH is annoying but having more slots and way better breakers has been super nice to have for a complicated design this year.

REV Mini Power Module: We’ve iterated on our ‘custom circuit’ several times this year, the MPM has made that easier and faster. This will be on a lot of our future robots.

REV MAXPlanetary: Absolutely love. Switched from VersaPlanetary for a couple of systems this year and never want to go back.

REV UltraPlanetary: Another great gearbox, super nice for low load applications like shooter hoods.

ThriftyBot Telescoping Kit: Great kit, good pricing. We machined UHMW slider blocks to replace the 3D printed ones but aside from that has been completely bulletproof and made our lives easier.

WCP Greyt Turret: Extremely disappointed in the quality of the 10 DP gear mesh, will NOT be using again.

Falcons 500s: Great motors when they work but the myriad issues are scary. I’m still not sold on the non-replaceable controller or the spline shaft. We’ve used them to save space but I’m not sure if we will do so in the future.


I guess I have to say I am disappointed with REV this year.

It started out with Neo shafts that were .312 instead of .315. We use the AM Evo Slim SS gearboxes with the pressed on 16t pinion. On the .312 shaft the pinions slid right on. We had multiple failures on both our practice and comp robots. Ended up pulling the Neos off our 2019 bot and using them. REV support said that a .312 shaft size is within the tolerance range. A December shipment of NEOs had all the shafts at .315. The January shipment had them at .312.

As a side note, I don’t know how AM secures the pressed-on pinions when people purchased the Neos with pinions already pressed on. I would have thought they would have run into the same issues we saw.

We had at least 2 new Spark Max Controllers just stop working, one when we were simply driving unimpeded across the field during a match.

The REV Pneumatic Hub compressor control failed such that just turning the robot on would start the compressor (didn’t even have to enable the robot, just turned the robot on). The rest of the PH seemed to work. Ended up installing a CTRE PH on the robot just to control the compressor and left the REV PH installed so we didn’t have to redo the wiring on the PH.

WCP/GreyT Telescoping tubes were GreyT. Had to manufacture our own hard stops but that was okay.

Used the 3 motor flipped configuration WCP drivetrain gearboxes and were happy with their performance. Didn’t have the problematic gear ratio teams have complained about. Using Falcon 500 motors I’ve come to the conclusion now that 6 Drive motors is overkill and probably will stick to 4 most of the time now.

WCP 3.25 inch aluminum performance wheels - held up great. My only problem is the tread tool was never available in stock the entire season and the wheel part drawings don’t include information about the hole spacing for the tread and the tread tool page doesn’t include that information either. I emailed WCP about getting this hole spacing information during the season and still have not gotten any response whatsoever. Making the tread by winging it is not fun; do not recommend using without having the correct tool.

CTRE CanCoders - I have to say we had a lot of issues like… 2-3 matches of dead robot at least and it’s particularly because of how these sensors require the end user to solder the CAN and power wires in yourself. Now if I have to keep using them as they are now in the future I’m going to have to consider hot glue or epoxy over the wires post soldering. We just had far too many wire failures on these sensors this year. Please consider updating a design that uses your micro-weidmuller plugs or a breakout board with pins. Also I had a terrible time trying to get a Falcon motor to use the CANCoder as a remote sensor to control the position of an arm via basic PID. Never had any issues using the FX internal sensor or a SRX with a external Magnetic encoder. I don’t know why the CANCoder is so much worse to use but it really messed with us.

CTRE CANivore - with the number of CAN devices we have this year and will have in the future I can’t imagine we won’t be using this every year from now on. At one point early in the year we had 25 CAN devices on the robot. The robot wouldn’t have worked without this.

ThriftyBot color vectored intake wheels - worked well and we were very happy to be able to buy some with our team colors. Never saw a single wheel fail. As an aside we do think we probably could have gotten better intake performance from the VEX vectored intake wheels with a rubber roller but we haven’t had a chance to buy any yet.

ThriftyBot flex wheels - good compound flex wheels that lasted 2 events with no issues.

ThriftyBot hardware (hex collars, hex spacers, hex bearing, 3D printed part inserts) - all solid products that we had no issues with.

REV Maxplanetary gearbox - we used this gearbox on our high torque arm that pivoted or robot on the climbing bars. 1 Falcon 500 and a 125:1 gearbox. Zero failures under lots of load I’m sure. I also provided another team one of my extra gearboxes to use on their climber winch (343) and to my knowledge it never failed on them either. In my opinion I may well not buy another VersaPlanetary ever again unless packaging requires it… that’s how much I liked this product.

VEXPro Versaframe - is still my go to choice for robot metal, but It’s getting pretty expensive now and I may consider doing raw aluminum tubing now since our team finally has the capability to do hole patterns ourselves.

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We plan on using the 18:30 stage instead of the 16:32/ We had an assumption it was some kind of catastrophic failure as well because the gears showed no sign of wear before they broke & one of our replacements only lasted a minute.

WCP said that they would prevent these gears from being sold with the flipped gearboxes in future years.

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There have been a LOT of positives this year, many of which I’ve had experience with personally and some of which I’ll use other folks’ experience to plan for the future.

  • The MK4i have done so well for so many teams whom I respect and communicate with, that we just purchased a robot + spares for next year. We will use them for an off season robot and perhaps transfer them to a FRC bot if the game calls for it. These just seem like the peak of what swerve can be.

  • The telescoping kits (Thrifty, AM, and WCP) all seem to be excellent. Like others, we used Thrifty with milled hard stops and they have never failed us.

  • Rev MaxPlanetary has completely replaced the Versas on our robots going forward, they are that good.

  • Falcons are a really mixed blessing this year. The issues are well documented and range from frustrating to alarming, BUT, we did everything we could to ensure that ours were fixed properly and they have gone on to work great through two full competitions and a lot of hard practice. Assuming that this continues at Champs we will keep our stock of these motors and use them. Future purchases will wait until a replacement comes from somewhere else, or until I am confident in Vex QC (which will take some doing). I don’t mind being a guinea pig sometimes but I don’t want to be a fool.


AndyMark Climber in a Box was the most important COTS part we had this season.


Another +1 for the AndyMark Climber In A Box. Various circumstances led to us finally getting ours in Week 5 of build season; we found the instructions to be intuitive (especially for a brand new design) and the mechanism worked flawlessly as intended. We had them assembled, installed, and working within a day (we had scheduled 3 days) and without them, we would not have had the on-field success we did.