Is there any cost effective swerve drive options?

Please calculate, side by side, your realistic manhours building custom swerve and the same # manhours working at Starbucks then buying the modules.

I promise the latter wins on the field and in your budget, before even considering their generous tuition reimbursement program :wink:

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And then comes the programming. You’d be lucky to have it be able to drive in robot-oriented by competition. Let alone field-oriented.

I appreciate the references to CheapoSwerve, I never intended that to be the official name, but I guess it’s stuck :P.
I’ve been iterating the design for the past 4 months or so for a separate project, and have since made it way more viable for FRC-related testing. It’s been assembled, iterated, tested, and it works really well.
Here’s a link to the updated design, and here are a few teaser shots:

Of the module in it’s V2 form…

Of my project… TippySwerve (chief post coming soon)

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If you want to build a swerve for the sake of having one, I highly suggest looking into FTC Team 11115 Swerve. It will be cheaper and easier to drive safely wherever you want.

If memory serves me right, most of the parts can be 3d printed and will be much more cost effective. Also, if you are looking into control systems as well, take a look at this thread and this thread I posted to group building a mecanum bot for a school project. It is significantly cheaper to not got through FRC/FTC legal hardware and do Arduino instead.

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hey, I was just looking at mucho cheapo swerve thanks for the updated cad. is there a part excel sheet for this one too?

Thanks so much

Eh, You’ve got about 6 weeks pre season. The last time I did a clean room swerve implementation it was sit down and code for about 4 straight hours to get robot centric working and then field centric was about another 10 minutes to implement (and then about a week to debug because I didn’t have hardware and the gyro used one direction for positive and the robot for the other which led to weird results)

(For the record, my field centric code is in its entirety below, it’s really quite simple matrix math)

public static Vector2d TransformFieldCentric(double x, double y, double headingDegrees){
    Vector2d control = new Vector2d(x,y);
    control.rotate(headingDegrees);
    return control;
  }
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Out of 4 swerve implementations that I’ve personally witnessed, none of them were able to get absolute encoder offsets to behave within 2 weeks. There’s a lot of little things that make swerve more difficult to implement. For example, few teams know a good way to properly align the wheels to the coordinate system before setting absolute encoder offsets.

EDIT: these were all within the last 2 years

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And the last one I’ve done, from scratch, took way less time than that.

There’s some gotchas but it’s not insurmountable. With the explosion in software support and example code the last few years it’s only gotten easier and easier.

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I said the same thing until I started. Took me about a month overall–and that was with essentially full documentation of the 3-month struggle my brother went through last year to do swerve.

I don’t have a BoM just yet, but poke through the CAD, you should be able to see which parts are which, and what you’ll need to buy.

Without going too in-depth, the hardware you’ll need is:

  • 2 types of short m3 bolts (m3x15 and m3x20)
  • Long m3 bolts, for gear and wheel axles (m3x35)
  • m3 nuts
  • some m3 ID bearings, 12mm OD if I recall correctly, but check the cad on that one
  • 6mm airsoft bbs
  • rigid 3d printer filament (I used duramic PLA+)
  • flexible 3d printer filament (I used overture 95a TPU, it’ll print great on a stock ender 3 or similar bowden setup)
  • rev thru bore encoder
  • drive and steering motors with ultraplanetary gearboxes

The main cost drivers are gonna be the last two, but the above items should run less than $20 per module, assuming you build 4.

I’ll post a proper BoM when I post my project overview, but don’t wait up for that.

Assembly should be very straightforward. If you decide to build one please DM me or start a new thread; I’d love to help :slight_smile:

Hey I am buying a 3d printer and will get to work on it and other projects. What printer would you suggest. I am fairly new to 3d printing but want something quality I can use to work on projects while in my dorm room. Also Skiddy - have you thought about using metal PLA and print it all in metal for more durability. I do not have any experience with metal PLA so maybe this is not optimal let me know. :smile:

Uh… NO. This is what’s called unobtanium. You can’t do all metal AND “metal PLA” simultaneously. And any printer that can do metal at all is going to be far more expensive than just buying the swerve modules. (Let alone material costs.) And it’ll have extra steps (typically 1-2 extra units). You thought a Markforged was expensive, you ain’t looked at the price tag on a Markforged Metal X.

It’s far more economical–for a swerve drive at any rate–to make it on a machine/have it made, than to buy an industrial-grade machine for a dorm room.

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Hey eric, I recently reading about a filament that lets you print metal on all 3d printers and was wondering about that. https://thevirtualfoundry.com
That being said. What printer should I buy to be able to print the cheapo swerve from plastic ?Onshape
Thanks Eric

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I read about this as well, it’s pretty neat. I don’t think you’d get the real benefits of metal printing, though, which is stiffness and layer bonding.

Short of carbon reinforced stuff like from a markforged or SLS printer, most of the data I’ve seen shows PLA+ to be the next best structural option (in stiffness and durability). There’s less data comparing filament types for gears, both for strength and lifecycle wear, though.

I’ve put this module through the ringer with all PLA parts and have yet to have a material failure. The geartrains have all been strong enough to hold stall torque without shearing or flexing. I’m using pretty weak motors, though, and my load cases don’t really mimic FRC play. I’m most worried about the bevel gear for drive, it has kinda thin walls and could flex or shear.

Has nobody mentioned mechanum wheels yet?

“Back in my day”… that was the quick and cheap way to get a bot that can move any direction. Not a ton of traction for pushing, but it will drift and spin pretty similar to a swerve drive.

Very interesting.

And to be blunt, expensive as heck. First print, then sinter, and if you do it wrong or can’t get it to the oven without it breaking, start from scratch. That’s where we point you to pros.