Size of 6" Colson Performa Wheels

My team is looking at running an 8 wheel drive train configuration with the center four wheels being 6" Colson’s and the corner wheels being Vex 6" omni-wheels. I know that the 4" Colson’s that Vex sells are about .060" undersized. Do the 6" wheels have this same property? I couldn’t find CAD files or drawings on any of the sites selling these wheels or documentation on the Colson Caster website. In order for the Colson wheels to properly engage with the carpet I was planning on dropping the two center wheels enough to make them level with the omni-wheels plus about 1/16". If any teams have insight into a design like this I would really appreciate it.

I’m not sure as to whether the wheel is undersized at all, but we used the 6 in Colson wheels last year and have the CAD file for them. I have attached it for you.

4468-18-Robot-P002- 6in Colson Wheel.step (2.0 MB)


You can always add a shim to the center wheels’ gearbox/mounting points to increase the drop. Or drill offset holes to move them elsewhere.

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Where do you guys find 6" colsons? I can only ever find 4".

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The Vex colsons with molded in 1/2" Hex hubs only go up to 4".

You can get 5", 6", and 8" in several widths elsewhere, for example from The Robot Marketplace. These have a plain bore that will need a pressed-in hub for use with 1/2" hex.

The 6 and 8" can use Vex’s colson hubs (either direct from Vex, or from Robot Marketplace).

The 5" wheels have a smaller bore though, and would require a custom hub not available as COTS.

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Thank you. That’ll be put to good use.

the 6" x 1-1/2 Colson are out of stock at the Robot Marketplace… just found out that the Caster Depot has 100s of them in stock in Grand Rapids.

(And for anyone wondering - yes, the nominal 6" colsons are also between 1/8 and 1/16 undersized from the nominal dimension)

Do they have an online webstore, or do you need to contact them directly for sales? I’m trying to source some 6x1.5" colsons too.
I found this. I couldn’t locate any performa wheels without the caster attached, but it appears that the caster only attached to the wheel with a hex bolt and lock nut which should be easy enough to remove. Hope this helps.

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I just got off the phone with Dean at Caster Depot. He was great to deal with. I placed an order with him over the phone. They are able to send me the wheels without any bearings pre-installed. Also, they were cheaper than robot marketplace.

Do the colsons they sell have the same size bearing hole so that the Vex live hubs can be used?

I’ve been informed that the Robot Marketplace has closed down. Their website will still take orders, but nothing will ship and nobody is answering the phones anymore.

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Looks like you may be right - I tried to look up their retail location in FL (Hobby Marketplace) and it shows “permaneantly closed”. I was even able to find a photo showing a ‘Store Closed’ sign on the door. Looks like they went out of business June 2019.

Thanks for sharing the warning.

Shame to lose a supplier, I’ve ordered from them many times in the past 8 years always with good results.

I contacted them about their Colsons and they said they expect to get a delivery this week and ship as soon as they get them.

They can also be purchased from McMaster Carr

Have to install your own hub though

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I can’t find the CAD on that link, which is weird for MC, and am trying to figure out if these will accept the Vex live hub.

Can you remove the ball bearings that are already in them. And thanks, I had no clue McMaster sold Colsons.

Don’t be fooled by the little preview picture.

Yes, they can come off by hand.