acme leadscrew grease?

[Numb Nut]

I see that one of the milling machine preparation guides suggests the use of "white lithium grease" for the table leadscrews...

Unfortunately I don't happen to have white lithium grease specifically, but I do have to have 2 tubs of grease with lithium mentioned on the labels:

1. Granville brand - CV grease, lithium based no.2 containing molybdenum disulphide (MOS2) (black colour)
2. Duco brand - general purpose lithium grease, high melting point (yellow colour)

Alternatively I could use some 68 slideway oil.

Are either of those ideal for the leadscrews or do I need to buy myself a 3rd tub of grease?

Just trying to avoid accumulating yet another tub of grease but not at the expensive of unnecessary wear and tear on the leadscrews & split nuts.

[Numb Nut]

I've been doing some "research" on grease... it's almost as much fun as getting the milling table back together and being creative!

So what is lithium grease? Amazing what you can find with google.

http://lubricants.co.uk/lithiumgrease.html
http://en.wikipedia.org/wiki/Lithium_grease

Seems "lithium" refers to the method used to convert oil into a more solid form. The base oil could be either mineral or synthetic. Other additives could be added for specific applications.

The thickness of the grease is another variable - and it seems it's usual for the manufacturer to specify this on the NLGI scale.

http://en.wikipedia.org/wiki/NLGI_Grade
http://www.nlgi.org/

The no.2 grease that I mentioned in my first post would appear to be NLGI grade 2 - moderately soft like peanut butter according to wikipedia.

So what's the difference between white lithium grease and lithium grease? Is it just the colour?

According to some references the white colour may assist in determining when further application grease is necessary. Is that a useful property for a milling machine's leadscrew lube? Probably not, the leadscrew is hidden away.

http://www.wd40.co.uk/index.cfm?articleid=36

So what is the colour additive? A look at the safety data sheets for various white lithium grease reveals it to be zinc oxide (ZnO).

http://www2.dupont.com/Products_and_...ase%20MSDS.pdf

http://www.3inone.com/files/pdf/msds-3in63852419.pdf

http://www.crcind.com.au/catalogue.nsf/(MSDS)/WHITE%20LITHIUM%20GREASE%205037%20ncr/$FILE/MSDS.pdf

http://en.wikipedia.org/wiki/Zinc_oxide

It seems the white additive might also serve as a useful friction lowering compound and a corrosion inhibitor.

http://www.technologylk.com/product/...Cans-Case.html

http://dx.doi.org/10.1016/j.wear.2007.11.013

There are also greases made specifically for leadscrews.

http://www.electromate.com/db_suppor...l%20Screws.doc

http://www.universal-thread.com/lead3.htm
http://www.universal-thread.com/media2/KS-46_MSDS.pdf

Related info:

tribology - the study of moving surfaces, friction, wear and lubrication.

http://en.wikipedia.org/wiki/Tribology

--

Thoughts anyone?

[neilw20]

I have used this on gears and screws as it resists being flung off.
I no longer have technical details, but this was blue colored grease, and really sticky.

http://www.azom.com/Details.asp?ArticleID=2231

The following helps make sense of the characteristics:

A grease is best thought of as a sponge full of oil, with the sponge being the “base“ or thickener. It holds the oil and additives in place and gives the grease the basic characteristics such as drop point and water resistance. The oil content, typically 80-90% of the grease, provides most of the lubrication performance. To achieve the desired characteristics of a grease, careful selection of base lubricating oil viscosity, base type additives and fillers is essential.

...

[Numb Nut]

Neilw20 - thanks alot for that link - was an informative read.

Meanwhile have noticed that Moly isn't generally recommended for ball bearings:

http://www.opieoils.co.uk/p-6315-cas...ly-grease.aspx

http://www.smokstak.com/forum/showthread.php?t=6446

[Numb Nut]

Got a quick reply from Abssac http://www.abssac.co.uk to my query of what grease they would recommend for use with steel leadscrews into a bronze nut - their tech guy recommended Rocol Sapphire 2 bearing grease:

http://www.rocol.com/lubricants/engl...s/prod0054.php

Datasheet is here:

http://www.rocol.com/tsds/live/tds/e...%202%20TDS.pdf

It's basically a very refined NLGI grade 2 blue grease with long life and high load properties. Doesn't appear to contain zinc oxide however.