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14 Printable LM8UU linear bearings test plate

by DeuxVis May 7, 2014
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Nylon is hygroscopic. I have used it for parts and it changes shape as it swells up. I would think nylon would bind as it swells?

Thanks for this, I printed all of them (and 3 more that are not one this file), and I founded 6 that work great on my printer !
The one I prefer is this one :


LM8UU Linear Bush
by Gyrobot
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It seems you never got around to getting back to this. Funny thing is I was just watching a video on a LulzBot mini and it looked like it had plastic bearings. Of all the issues I have with my franken SD3, replacing the LM8UU bearings with my printed ones has not been one. I like they are a little snug and reduce slop, even if the motors have to work a little more, they break in quickly and stay snug because of the crush fit springy design.


FWIW, my Y axis bearings got crunchy so I replaced them with the plastic bearings of mine you have remixed here and they are working fine.

Thanks for the notice. As far as I remember your model was among the working ones indeed.

I'm sorry I wasn't able to take the time to write a summary of my experiments yet. Will do, just can't tell when.

I'd love to be really scientific here but I don't think I have the appropriate measurement tools and methodology background, so I'll go for a sort of try and feel approach. En français : au pifomètre :)
To be specific, I have manually tested sliding them on a rod, and for some of them which were too tight I spent some energy starting to wear them off to see if the friction will decrease.
My selection criterion is a balance between easy fit, good sliding and the lesser possible clearance (actually, more like the less lateral movement possible).
Testing how much they wear could prove time consuming ,so I'll skip that for now.
I have done some testing already, expect me to publish it during the next days. I think I have a candidate - sorry can't remenber which one right now - which is as good as a cheap metal ball lm8uu, or even better, on all the aspect (except wear of course).
From memory, 4 or 5 of them have really similarly good results.
Not surprisingly, the wood (oak) bushing I milled is too tight and has too much friction as is, maybe I should also try with some sort of lubrication which won't damage the plastic (silicon grease ?).
Of course I still encourage anyone to try for themselves, the result is probably highly dependent on my specific parameters (nozzle size, printer accuracy, plastic used...)

A first test could be to add a load on the bushing, put it on a rod, and tilt it. The different angles the bushings start to move will give you a friction coef. chart...

what is your criteria of selection ? wear ? dimensional clearance ? friction ? how do you want to measure your criteria ?