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Unread 10-17-2018, 01:08 AM
FMS FMS is offline
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Swerve Pivot Bearing

What pivot do you use for a swerve drive? I would like to make my own similar to this one:
https://www.chiefdelphi.com/forums/s...ghlight=swerve

Is that just a normal ball bearing? Where do you get these? I want to keep the robot COG low so I want a big bearing like the one used in the above module. Where can I find bearings like this? I checked Mc Master and didn't see anything. Are the companies that give quotes FRC friendly or do they requre large minimum orders?
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Unread 10-17-2018, 01:33 AM
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Re: Swerve Pivot Bearing

Large bearings are readily available on Ebay in the form of 68xx series bearings. A 6814 has a 70mm inner diameter and is well-suited towards bevel-beside-wheel swerve designs.
You can also find Kaydon ripoff bearings on aliexpress and alibaba if you want a smaller form factor. I ordered several KA030XPO bearings (3" ID x 3.5" OD) from a supplier on alibaba for only $20 each, for playing around with.
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Unread 10-17-2018, 01:33 AM
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Re: Swerve Pivot Bearing

Look up "Lazy Susan" bearings. McMaster does have a few; so do other places (home improvement stores, for example).


Also... McMaster happens to sell bearings with up to an 8" ID. Though that particular one is about a fifth of the robot budget by itself, and definitely over the single-part limit. (Actually, any bearing over about 4" ID from McMaster would likely be over that limit, except the lazy susan or turntable bearings.)
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Unread 10-17-2018, 01:37 AM
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Re: Swerve Pivot Bearing

That's a 6824 bearing, which you can find on ebay and aliexpress for about $20 iirc for singles. Haven't bought any myself but I can't imagine they're terribly bad. It's an X contact type which means it can take thrust as well as radial loads. Smaller 68xx bearings are popular in bevel beside wheel swerves as well.

I have some advice for making a swerve like that... Don't. Especially not as a first swerve drive or first CAD exercise. That style just has some inherent weaknesses which are expanded on a lot in the thread. If you want low CG, go for a standard bevel beside wheel design and maybe flip the drive motors.
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Unread 10-17-2018, 01:44 AM
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Re: Swerve Pivot Bearing

Quote:
Originally Posted by EricH View Post
Look up "Lazy Susan" bearings. McMaster does have a few; so do other places (home improvement stores, for example).


Also... McMaster happens to sell bearings with up to an 8" ID. Though that particular one is about a fifth of the robot budget by itself, and definitely over the single-part limit. (Actually, any bearing over about 4" ID from McMaster would likely be over that limit, except the lazy susan or turntable bearings.)
Lazy susans can explode very easily when used on FRC robots, so be cautious. The large sealed ones work better than the semi-open ones, but the best solution is to just spend the extra $10 and get a 68xx or Kaydon knockoff bearing.
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Unread 10-17-2018, 08:22 AM
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Re: Swerve Pivot Bearing

What about something like this?

https://www.grainger.com/product/BL-...ust-BRG-35TY06
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Unread 10-17-2018, 08:26 AM
Seth Mallory Seth Mallory is offline
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Re: Swerve Pivot Bearing

192 has been making their own bearings in our swerve drives. The first year we used plastic plate and made the plastic slip against delrin. Last year we made aluminum races and installed ball bearings in the groves.
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Unread 10-17-2018, 08:45 AM
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Re: Swerve Pivot Bearing

Quote:
Originally Posted by asid61 View Post
I ordered several KA030XPO bearings (3" ID x 3.5" OD) from a supplier on alibaba for only $20 each, for playing around with.
We also used these Chinese Silverthin bearings for our swerve modules this year. The cost isn't too bad and their size and weight are great.
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