Linear bearing grease

[Claude Boudreau]

I`ve build a cnc router with linear bearing (thk sr25), now before packing it with grease I would like to be sure of the right type to use.I`ve read Lithium soap base low viscosity grease. Now there must be a grade or Index for viscosity (similar to oil 10-30 and 80-90) What should I ask for? And can you overpack a linear bearing?

[RICHARD ZASTROW]

Greasing linear bearings without very good wiper protection might cause more problems than protect. Dust, grit and grease can foul things up a bit.

Dick Z

[fatal-exception]

the SR25's I have come with excellent seals.

I'm using P2 grease from THK (lithium based), which is expensive and intended for precision ball screws. It's very thick, but has a wide temperature rating.

If you download the documentation from the THK site for linear bearings, it will tell you what kind they recommend.

[Claude Boudreau]

Originally Posted by fatal-exception the SR25's I have come with excellent seals. I'm using P2 grease from THK (lithium based), which is expensive and intended for precision ball screws. It's very thick, but has a wide temperature rating. If you download the documentation from the THK site for linear bearings, it will tell you what kind they recommend.

I`ve read that too high viscosity could stop the bearing from circulating causing uneven wear .

[fatal-exception]

I suppose that's possible that the balls could skid rather than roll, but since they make the grease for ball screws, I tend to trust it.

[Claude Boudreau]

Hi, I`ve finally found the scale I was looking for in wikipedia , look for NLGI grade
http://en.wikipedia.org/wiki/NLGI_Grade
The National lubricating grease institute rate the grease from 000 to 6
from liquid to almost solid . Do you have a NLGI number on the THK grease your using?

[fatal-exception]

Peanut butter...

[Claude Boudreau]

smooth or crunchy ... I`m getting lost here...

[fatal-exception]

Anything will work, as long as it's kept clean. P2 grease I would estimate a number of 280 on the NLGI scale. (why are there gaps in the scale anyways?)

[Claude Boudreau]

All of the grease I`ve seen around are NLGI no.2 when it`s indicate at all . I can`t find a lower viscosity locally, I`m taking my chance with white lithium (NLGI. no.2)

Never notice the gap , not sure why either.

I`ve seen what look like extensible dust booth for round linear rail , wonder if anyone seen something similar to protect thk rails from dust?

[fatal-exception]

They do... The ones in the pic fit perfectly. They screw through the end of the recirculating ball housing into the steel body.

I need some on the ball screw...

Paul

[Claude Boudreau]

I was thinking of what they call protective bellow
http://www.cnczone.com/forums/showthread.php?t=54081
They were round and be perfect to protect acme screw or ballscrew from dust
OK got info here
http://www.nookindustries.com/slides...llowsBoots.cfm
I guess all I needed was the right name for it, lucky I saw it on the tread above.