Hey guys, Is there any cost effective way to build a swerve bot without the high price tag of each assembly?
I understand this is sort of counter intuitive because precision and quality have a cost but any insight is helpful.
What shop equipment do you have available?
Back in Ye Olden Days (of like 5 years ago and before), you didn’t go out and buy a swerve drive, you built your own. Takes a few key pieces like a mill or router, though, possibly a lathe. But if you don’t have those (or access to them, or a sponsor with them), things get a bit more “interesting”.
And, as an exercise, do a cost accounting of the modules you build, including labor at suitable rates. You might have a surprise coming up.
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Honestly, not really. An example, here’s the bill of materials for Nick Coussens custom swerve, you still looking in the ballpark of ~$300 per module.
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I strongly recommend against this. If your only option is to make a custom swerve, you’re better off going tank until you can afford to do it properly. You’ll waste valuable days or (more likely) weeks, just getting the drivetrain together, it’ll cost nearly as much, and it’ll ultimately perform worse than the COTS options. Put those effort points into the rest of the robot, IMO.
I have a design for a cheaper printed swerve, but it’s fairly bulky and needs revisiting. If you look up “Aliswerve”, you’ll find it. It also has not been stress tested, but it is only $150 per module, plus drive motors and a brushed motor controller. Probably fine for software testing, but not really suitable for the season.
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Hey, thank you I am recently graduated highschool and want to build my own swerve as my team never got to it while I was there. I have this idea that if I can build these more complex assemblies then when I return to mentor in a while I can get the team to try for a real quality bot because I have the proof it can be done by one person.
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I will use that option I dont think that there will be any stress on the bot just want it to mess around with
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Debatable. If (big if) you can design, manufacture, and thoroughly test a swerve module in the offseason, and then just punch out a bunch of modules in the first few days of build season, that’s viable.
To be clear, though, that’s a pretty niche case. If you have the organization and CNC capability to pull that off, there’s a decent chance you can afford COTS swerve modules in the first place.
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If you are just messing around with software and stuff, this may be a viable option for you:
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We make our swerve modules. If we buy all new components and do not reuse any cots items, our cost this year will be around 3060.00$ for 8 modules. Includes all raw materials, parts, motors and controllers. Cut in half for 1 robot. Many of the items include shipping but some do not. Many of the parts are 3d or resin printed. This allows manufacturing when not at meetings. 24-7 if we want. If we pushed it we could finish in week 1 but most likely will not. Prototyping will dominate week 1 and 2. We have been been manufacturing modules since 2010. For a first time it will take way longer. There are many many details to hang up on. This would be a major effort for most teams or individuals.
I should note that the window for ordering our swerve module parts from China is rapidly closing for a late December receiving. We will place our orders on 11/11.
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You could ask around if teams have older versions of current models they’d be willing to sell for cheap. This can be an inexpensive way to try it for the first time. You might have to replace some individual parts or find a few teams with extras to make a complete set. They might not have the latest and greatest packaging, weight, gearing, or wheel width, but they still work great and I’m sure you can do it cheaper than the cost of new modules.
If any teams are looking for some MK3 parts let us know. We upgraded our MK3s to MK4s and still have the leftover parts if those are useful to someone else.
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We tried to do this with out first swerve drive. We spent two years trying to make our own, based of another design. One of those years (Stronghold) we decided it wasn’t a good game fit. Then we broke down and went with MK2.
We ran MK2 and then MK3 and then a hybrid version of MK3/MK4. This years we are making a full transition to MK4i. I run a good sized machine shop and sponsor/mentor the team. I looked at making the parts in house this year and decided it was cheaper for me to buy the SDS kits and donate them to the team instead.
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Yet another - “Are you on my team?”
We sent the design published by a “world-class” team to a local machine shop (which may or may not have been a sponsor). It was hard to get the tolerances we needed before we even assembled the parts. Finally modules almost worked smoothly in the air (on blocks). The robot on the floor bound up somewhere between seconds and minutes of use. There wasn’t enough time or grease in the world to keep it working.
I’m not sure cost effective is the right word here.
The SDS and other offerings are incredibly cost effective. We used to pay the same price nearly 20 years ago for the first andymark shifters! The swerve module at least has a wheel in it too 
Can you make them cheaper? Marginally yes, as others have pointed out… But with far more labor invested by your team which is likely better spent on other efforts.
What’s the right answer? Depends on the goals of your team.
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I think it’s also worth pointing out that if you are just messing around with swerve, you can get away with 2 modules only - Then use casters in the other corners. Don’t necessarily recommend that for competition play (I know of teams that have), but all the principles apply.
You can also get away with not including an absolute encoder, and manually aligning the wheels, if that’s helpful. Then just use an incremental encoder, like the one on PG motors (or inside brush-less motors).
And if you are just driving it around for fun, you don’t need an encoder on the drive motor.
These options should reduce the price tag dramatically for you if you just want a demo chassis.
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I’ll also throw the “Mucho Cheapo Swerve” into the mix from this time last year. If the goal is a test bed for code, or just proof of concept that you can make a swerve drive, it doesn’t get much cheaper than this (especially if you already have access to a 3d printer).
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Remember, “world class” in FRC != world class manufacturing practices or documentation. FRC is a race to cut corners the most efficiently. Some of the top teams put together technical binders and extensive internal documentation, but many more don’t.
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This is interesting. I’m not a top team (I’m just a person) but here’s a quick ad for Extensive Internal Documentation:
Are you tired of all your work being ephemeral?
Do you want to do stuff that makes a positive impact on more than one cohort of participants?
Does information entropy make you sad?
It doesn’t have to.
Extensive Internal Documentation.
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This reads like an as-seen-on-TV ad, and you’ve got me SOLD!
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We built Nick’s Winter 2021 swerve… The limiting cost factor is really the motors/drivers.
The Mucho Cheapo looks like a great idea for just getting driving!
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