<6" Wheels for Outreach Robots

Are there wheels that are less than 6 inches and can survive driving on asphalt?

My team is building a drivetrain for outreach and programming. At first, I designed it to have 4" colsons, but I realize that they would wear out pretty quickly once we start doing outreach events outdoors. Our old outreach robot uses 6" pneumatic wheels, which worked pretty well. Unfortunately, 6" wheels make a flipped gearbox very tall. Flipped gearboxes in the corners of the drivetrain would leave the most space for prototyping mechanisms.

Maybe something like this?


Our manufacturing capabilities are pretty limited (especially with COVID) so it would be really nice if there were a COTS wheel. I don’t think my team has ever made custom wheels before.

This maybe?

I recommend you keep 6" or greater diameter wheels on any robot you intend to demo outdoors. 4" wheels leave you with 1" or less ground clearance. Door thresholds and curb ramps can easily exceed 1", causing a low robot to get stuck. That’s been our experience demoing our 2017 robot.

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Thank you for your advice. That makes a lot of sense.

After completely ruining a set of 6" hi-grips driving on concrete at an outreach event in 2019, we swapped to 6" 80A smooth grips and haven’t replaced the wheels since. Not exactly what you’re looking for, but likely something similar in a 5" format would work well.

Since your aim is for outreach and programming, you do not need to feel so constrained by the usual rules governing robot design and the usual practices such as compactness. It is likely (hopeful) that this drivetrain is in service for a long time so I would suggest that serviceability, adaptability and robustness should be high priorities i.e. it should be easy and inexpensive to replace wear items like your wheels.

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We have used our 2016 robot for outreach since the 2016 season ended. We often do demos in parking lots where we drive around to collect the boulders and then shoot them (kids love to play catch with that bot). We have destroyed a bunch of boulders on concrete/asphalt surfaces, but we have not needed to replace the wheels on the bot.

The wheels we used that year are the predecessor to the Vex VersaWheel DT, I believe. They look very similar anyway. They are 4" and used on a swerve chassis, so not much by way of scrubbing. You can tell that they are worn a bit, but the tread is still sufficient for outreach.

I suspect the current VersaWheel DT would do pretty well on parking lot surfaces. The durometer (65-Shore) is a bit softer than the other options cited in this thread. And your mileage may be significantly less than what we have experienced if you have a skid-steer chassis with a decent amount of scrubbing.

Years back we experimented with some 4" pneumatic wheels we found on McMaster that had to make custom hubs for (since there wasn’t really a COTS solution for driving them).

That said, as others have pointed out, typically ground-clearance is your friend when it comes to outdoor robots. Our current Outreach Bot / T-Shirt cannon is built off of a KOP chassis (probably an AM14U2) that we modified to use AndyMarks 8" Pneumatic wheels.

Because the robot has a relatively low CG, the 8in wheels work great for a variety of terrain. We’ve taken it everywhere from school assemblies, homecoming parades (including pavement/gravel/grass), an OHL hockey arena (on the ice), and more. After a few years of wear, the only real complaints we have is the wear on the plastic parts of the kit, namely the gearboxes and the wheel hubs (though I did just discover AM’s Aluminum HD Pneumatic wheel hubs, so we may have to try those soon).

Personally, I would avoid most of the non-pneumatic wheels sold for FRC applications if you’re going to be using it on any kind of pavement. FRC wheels are designed for carpet and tend to wear down quickly on other surfaces (especially pavement).

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I made some 3D printed hubs to go with these 6" longboard wheels for asphalt/concrete demos. Haven’t been able to use them yet, but hopefully we can later this summer!

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People seem to like this wheel, so here’s a pic of the ‘test fit’ on our IR practice chassis.

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WheelPlanetary

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Mind sharing your source for that wheel? It looks awesome.

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I had several people asking me where I got those green wheels…

I got it from DIYeboards.com . These are solid rubber wheels that are a pretty heavy, even with all the holes! They come in a number of colors. I also have a hub design that mates up to the VEX hex hub if anybody is interested.

diyeboard.com

[6’’ 150*50mm 70A Airless All-Terrain Off-Road Skateboard Wheels 6’’ AT…

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Don’t have any suggestions for 4in wheels unfortunately but I’ll add myself to the group recommending you stick with wheels that give you some decent ground clearance. Especially given your location atleast according to your CD profile. If the roads and parking lots out here are bad I can’t imagine what they are like closer to Boston.

As for the tall gearboxes you could always try mounting the motors off to each side of the wheel rather than right next to each other on top of the wheel. Of course this suggestion makes assumptions that you’ll be using 2 motors per side and puting the gearbox on the center but if both of those are true I would explore it.

I also agree with those saying you should consider regardless of choice designing the bot such that taking a wheel off is easy. If it’ll be used for outdoors outreach I’d wanna design it to either be easily repaired or be way overbuilt for it’s purpose.