We are considering doing swerve drive next year for our robot and so far we’ve narrowed it down to either the MK4i or the Swerve X in the corner configuration. I was wondering what the differences are between them besides just cost (like durability for example) and if one would be preferable to the other.
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You can’t go wrong with either of them. SDS is in more durable than the WCP modules, but is slightly over 1lb heavier than the WCP modules. However, I would suggest the sds modules due to the SDS library making software much easier to implement.
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Can you qualify/quantify that statement? We have been using the WCP Swerve Xs (corner mount, flipped) and have had fewer issues than some of our peers that have been on the MK4i. My guess is that the durability is fairly equivalent between the two if you were to zoom out on a macro scale.
I will say that the MK4i looks like it does a better job of integrating into a chassis without supports other than the 4 external rails than the corner mount Swerve X. The Swerve X may be acceptable without external supports, but I was not courageous enough to try. The Swerve X corner mount moves the wheel slightly closer to the corner.
I was also slightly disappointed by the amount of screw engagement holding the treads onto the wheels for the Swerve X when compared with the MK4/i
Overall, my recommendation is to buy the version that is in stock so you are not waiting on the vendor(s).
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SDS modules are made of 7075 plate and has plates that are less pocketed, a second plate where the module mounts to the chassis, a much beefier wheel mounting setup, and all the gears and encoders are protected under plates.
Don’t get me wrong the swerve X is durable its just that the SDS module is a bit more so.
I haven’t heard of any failures related to the mk4i modules in the PNW events I have competed in, but also almost nobody runs swerveX in the PNW so I don’t truly know how it holds up in competition.
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It is only one data point, but we used SwerveX modules this year and they survived multiple falls at our first event before we fixed our climber, so I’d say they are pretty robust 
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Swerve X here. I would recommend designing and adding a shield for the encoders… The X doesn’t have encoder guards, and we added our own after we lost one during a match due to a hit.
The mk4i does have guards as part of the kit.
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I’ll add that I think the weakest point of either of the modules are going to be the bearings and not the plates.
Our swerve x have not yet failed in any way after a lot of PNW defense, falling 3 times, and even catching air on the cable cover.
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The plates can fail.
We’ve had one of our mk4 (not 4i) plates fail and bend at DCMP, not sure whether a fall or the cable protector caused it, but the bearings were just fine.
What match? And I would love to see a pic of the plates that bent.
Unfortunately we forgot to take a picture of it and we don’t know when it got bent, we just noticed randomly in the pits that one of the plates was bent. It was our front-left module that got bent if you bent, the inner-most corner was raised about 10 degrees and we hammered it back into place to get it back into alignment and haven’t noticed any driving or path following problems after the plate was hammered back.
Team 166 did this in a match at Pine Tree
These swerve drive plates definitely bend with enough impact (ex. falling off traversal) although I imagine the flipped versions are likely harder to bend
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My team is making a very similar choice at the moment.
Do any teams using corner Swerve X wish that they had used tube? The corner module looks like it might result in a weaker chassis.
Also, do you find that on your Swerve X, the treads are a necessity?
One last thing – for a team that wants to continue using our NEOs instead of buying Falcons, does one option become better? Is it viable to use the REV encoder and not the VEX one on either module?
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It is. you must put effort into figuring out how to build (and support the corner of the cassis appropriately. I expect @R.C will be publishing a few options about how to build the corner robustly sometime before next season. See this thread for more info: FRC 7407 WCP Swerve X Modifications
The wheels are smooth aluminum in both SDS and and WCP swerve modules. without treads on the wheels, you will not have any real traction. The treads Vex-pro (WCP) sells are good for about 6-9 matches depending on your driving style. There are other options that may survive longer from other vendors. edited for clarity
There is plenty of examples of successful teams using NEOs instead of Falcons for swerve. I have not played with the Rev encoders enough to understand how much if any internal backlash they have. Neos are just a touch shorter than falcons so that will result in more ground clearance. The other impact might be to how you handle heading control. With falcons, we take an initial reading from the absolute encoder and use that reading to set the offset on the internal encoder. The internal encoder to handle the swerve module heading after that. With a Neo, you would probably want to connect the absolute encoder to the motor controller directly and then use the absolute encoder for steering control.
We use the WCP Swerve X - Flipped, Corner Mount with Falcon 500s, CAN Coders.
I forgot to note that We did not regret the decision to go corner and will do so next season, game permitting, as well.
This where you can see the guide by WCP about using the different module configurations:
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I know the wait time for the Mk4i is really long. Ordered a set April 18th and still haven’t gotten them
Thank you so much! Great seeing you at BC22. I immediately resolved my own REV encoder question by remembering the built-in NEO encoders work just fine.
I chatted with some of your members on this at BC22. Did you do anything to combat this after your first plate bent?
Be sure to use an absolute encoder to measure the steering direction. Trying to align the module by hand at the start of the match is not viable outside of a testing environment. The Rev Through-bore encoders are absolute encoders and could be used to initialize the encoder position in the Neo.
We had only encountered the issue once and it was at worlds. We considered it a fluke and were fine for the rest of worlds so we didn’t make any attempt to prevent it from happenning again.
Day 2 of battlecry we bent one even worse but ran through the majority of elims with it and were still able to drive perfectly fine. (I’ll post a picture once I get one)
Moral of the story imo? Go with MK4i not MK4.
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As 2 other mentors from our team have said, we went with Swerve X Flipped, this year as our first competition bot to have swerve. In our first event we fell 3 times from the high bar, two of them we landed squarely on all 4 modules at the same time and the other time we hit “rear” first and then the fronts. The modules were completely unphased. I would definitely recommend doing a swerve bot over the summer (if you can meet of course), because gaining any bit of experience you can with both programming and driving the swerve drive train before having to actually do so in a competition season will serve you very well. There were definitely some issues we ran into with the Swerve X over the course of the build season but when we reached out to WCP they were very helpful. The first we encountered was that the directions were a little wonky for a few parts, you could still make out what they were getting at but definitely could have been better especially if someone had never put together a gear box prior to attempting these ones. We gave the feedback to WCP about it and they were grateful. The second issue we had, and its more of a manufacturing issue, was the bevel gears had to be matched up with the ones purchased at the same time otherwise the tooth profiles were off just enough to not mesh smoothly. We had purchased modules at 2 different times and the bevels at 3 different times (twice with modules, one over the summer for a swerve project.
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