Bearings or bushings? (Replacing linear bearings on rods)

Hi all,

So far you folks seem to be the best repository of information I've found, so I'm back with another question. I actually DID search the forums here, but nothing popped up specific to my question.

I recently picked up a used (but very nice) Max Micron Prusa i3 clone, and it sounds like a few of the LM8UU bearings need to be replaced. I began shopping and lo and behold, since the time I built my first printer (Printrbot Simple Metal), there have been certain new advances. I see that I have the option of using Drylin polymer bushings and Vesconite Hilube bushings as well. Do any of you have thoughts and experience with these? Are they worth the time and money, or should I go with a good quality steel bearing LM8UU? If you recommend steel, which manufacturer has the better quality?

Thanks!

Jack

what's the difference ?
Are the plastic ones just plastic ?
In which case you'd think they would wear quite quickly.
Or are they plastic with bearings inside ?

Don't see how solid plastic can be better than metal casing with bell bearings.

Yes, the plastic ones are plastic. The differences seem to be that plastic are all self-lubricating, have no moving parts, and can't wear on the rods. They are practically silent and their coefficient of friction is very low. That said, I'm not sure if the tolerances are good enough for 3d printing, which is why I asked here.

As for wear, I did see one calculation that suggests the polymer bushings can have a lifespan of 5000 km. Yeah...that's a LOT of printing. Still, I wanted to see if anyone here had any real pros and cons.

Jack

Quote:

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Originally Posted by curious aardvark

what's the difference ?
Are the plastic ones just plastic ?
In which case you'd think they would wear quite quickly.
Or are they plastic with bearings inside ?

Don't see how solid plastic can be better than metal casing with bell bearings.

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I can't see plastic either being as smooth or as long lasting or as accurate as a good set of steel guides with steel bearings.
I can see them being possibly better than a set of cheap steel bearings.

Got to be a video with comparisons somewhere.
Here you go: thomas sanlederer: https://www.youtube.com/watch?v=ZGBipbgwgME

So aluminium cased polymer bearings are best :-)