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Linear bearing compatible lubrication?

Posted by Mazaw 
Linear bearing compatible lubrication?
January 30, 2012 03:49PM
Just finished a Linear Bearing Prusa Mendel Iteration 2 build (short of a functional hot end, but I'm working on it), but this should be relevant to any design that uses linear bearings.

I'll admit I went bargain hunting on the bearings on ebay and got a pretty good deal and I'm very happy with the performance of them. The Z leadscrews, on the other hand, squeal quite a bit and I'm ready to apply a lubricant.

One thing I did not want to do for ease of maintenance is use one lubricant on the Z nuts/screws and a separate one on the smooth rods. I know (or at least I think I know) sometimes mixing lubricants can be problematic, and considering the cost and hassle of replacement, I'd ask which lubrication would be best for the bearings in the hopes it could also be used for the Z.

I'm open to buying some, but if I could get way with what I've got without dissolving or turning anything foul, I'd opt for that.

I have, in other of my ill-informed estimate of performance:
1. Magnalube (PTFE grease)
2. Teflon-added gun oil
3. Gun oil
4. Mineral oil
5. Silicone automotive lubricant
6. WD-40
7. Powdered graphite
8. Zinc stearate

Help from anyone who's been there would be great. I think the bearings came pre-lubed because during assembly while I was testing the alignment of things I would push cradles along the rods and sometimes they would leave a black "ring" around the smooth rod.
Re: Linear bearing compatible lubrication?
January 30, 2012 05:22PM
I use brass nuts on the lead Z screws and just a drop of machine oil.
Re: Linear bearing compatible lubrication?
January 30, 2012 06:12PM
Last time I just used some bearing grease I had left over from putting new bearings on my trailer, it is bearing grease so should be ok and so far 6months it has been

Experimenting in 3D in New Zealand
Re: Linear bearing compatible lubrication?
January 31, 2012 08:25AM
I highly recommend using a silicone based dry lube if you are using bushings as linear bearings. Due to the very tight tolerances you don't want a lube that dust or other contaminants can stick to. This is why most of them are labeled oil-less bushings. On real linear bearings (they type with ball bearings inside) I recommend using a low viscosity lithium soap based lube. I've seen many a linear shaft turned into linear splines because someone packed axel grease into their bearing causing the balls to stop circulating. A grease NLGI Grade 1 or 0 would work pretty good, though you might have a hard time locating some locally.

NLGI Grades - Wikipedia
Re: Linear bearing compatible lubrication?
January 31, 2012 04:41PM
I guess I'm reading that what's good for linear bearings (with ball bearings inside) isn't necessarily good for the Z lead screws and vice versa. That is, a light grease for the bearings with a light oil for the Z leads. I'm under the impression that I'm not really going to need to grease the bearings as often as I will need to oil the leadscrews since I didn't use brass nuts: I think nophead uses brass nuts too.

Thanks for the insight, guys!
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