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sarendt
02-10-2011, 10:54 AM
Has anyone thought about using ball bearings in their designs? Why or why not?

I haven't seen anyone with them, has anyone else seen them?

Cheers,
Scott

jes1510
02-10-2011, 11:17 AM
I have bearings in the free wheeling side of the leg joints of my mech. You can't really see them in any of the pic's but they are there. Here's the build thread:
http://forums.trossenrobotics.com/showthread.php?t=4570&highlight=plm

DresnerRobotics
02-10-2011, 12:06 PM
Has anyone thought about using ball bearings in their designs? Why or why not?

I haven't seen anyone with them, has anyone else seen them?

Cheers,
Scott

I have roughly 24 in use on Giger :P Most of the AX-12 bots you see use a bushing and washer instead of a ball bearing though.

elaughlin
02-10-2011, 12:16 PM
I had the idea of using ball bearings and making a pan slide ring out of milled aluminum. The thought was good, but most experienced robotists thought it would be unneed extra weight to have that. So I let go of the idea of using ball bearings.

jes1510
02-10-2011, 04:17 PM
FYI, these work as an acceptable drop-in replacement for the plastic bushing and washer that comes with the Bioloid kit:
http://www.lynxmotion.com/p-363-ball-bearing-with-flange-3mm-id-pair.aspx

DresnerRobotics
02-10-2011, 04:18 PM
How's the spacing using the Bioloid brackets?

jes1510
02-10-2011, 07:30 PM
They're pretty much perfect for the stock brackets. The thickness of the bearing is almost exactly the thickness of the bracket.

sarendt
02-10-2011, 11:36 PM
Wow, so there are a few folks using ball bearings! Thank you for the information, I just have a few more questions now :*)

Can you guys discuss why you choose to use them the way you did? Are there certain joints in the bot that need them more than others? How do you choose which joints? Is there any disadvantages to using them? Anything else we should know about ball bearings in regards to bots?

Cheers,
Scott

jes1510
02-11-2011, 12:16 AM
Well, how they are used really depends on your design. It's going to be different for every robot. I chose to use them on mine because of the weight on the legs, especially the knee joints. Every design is different. I probably wouldn't use them for some the size of the "standard" Bioloid biped simply because they aren't needed.

Downside? Price. They can get pretty expensive quickly. I already had mine from another robot but if I had to buy them I might reconsider. I would need 8 of them and at $5 a pop then it's kinda pricey. The flip side is when you are spending over $1k on a robot then a few bearings are probably worth it.

If you don't know anything about bearings then you may want to do some reading on them before you design them into a robot. Some need lubrication regularly and some are sealed and never need any maintenance. Make sure you know what you are buying.

billyzelsnack
02-11-2011, 09:33 AM
I typically buy my bearings on ebay. I just searched for a minute, but this is what I found..
http://cgi.ebay.com/Teflon-Sealed-Bearings-3x8-x4-bearing-flanged-10-pcs-/390072887345?pt=Radio_Control_Vehicles&hash=item5ad227e831#ht_1018wt_905
Maybe it's a match?