Overhauling a KDK Tool Post - What Grease To Use / General Grease Application

cinematechnic · Oct 20, 2017

I recently disassembled a KDK size 0 tool post for cleaning. I noticed it had a relatively thick grease which had a yellow/brown color to it. I want to get the toolpost back together and in operation as soon as possible.

Was wondering if anyone here knows what the right grease would be to use for this application - or if it even matters.

I haven't found a general guide to what greases are suited to applications. If anyone knows a source for that kind of info I would be interested to see it. I have so far been using the greases recommended by the manufacturers for specific applications.

Here's what I have on hand:

Kluber LDS 18 Speciale A (usually used as ball bearing grease, Schaublin headstock bearings and ARRI film camera bearings)

Kluber Staburags NBU 12 (spec grease for Swiss 6 and 8 jaw scroll chucks)

Dow Corning Molykote G-0102 (relatively heavy brownish grease, looks closest to what was in the KDK)

Thanks in advance!

AlexO · Oct 20, 2017

cinematechnic said:
1. I recently disassembled a KDK size 0 tool post for cleaning. I noticed it had a relatively thick grease which had a yellow/brown color to it. I want to get the toolpost back together and in operation as soon as possible.

Was wondering if anyone here knows what the right grease would be to use for this application - or if it even matters.

2. I haven't found a general guide to what greases are suited to applications. If anyone knows a source for that kind of info I would be interested to see it. I have so far been using the greases recommended by the manufacturers for specific applications.

Thanks in advance!

1. You need a high solids ( solid EP additives ) content grease. In a pinch, WHITE driveshaft grease. Better would be lead carbonate ( ?) paste, the stuff used for lathe centers. Even better would be leaded grease - wish you good luck finding that. And yes, it matters.

2. You'll battle a lot to find that and I don't think it's possible. There is some confusing BS from Kluber but in general things are so application specific it's impossible to have a guide. My father was sort of an expert in machine tools and lubrication and after a lifetime in the industry he wouldn't dare recommend you a grease for car wheel bearings. ( he would recommend NOT to touch Kluber

He hated them. ) . There is just too many variables. You, want the machine running forever. Industry, wants the machine running for sure for a limited period. BIG difference in lubrication strategies.

I often use a graphite spray for these sort of applications. Works wonderfully. MoS2 is good too but not if humidity may be present.

Conrad Hoffman · Oct 20, 2017

Unless you're running the toolpost at 5000 RPM or higher, I wouldn't think the grease was super critical. Why not any decent #2 moly or Teflon grease?

AlexO · Oct 20, 2017

Conrad Hoffman said:
Unless you're running the toolpost at 5000 RPM or higher, I wouldn't think the grease was super critical. Why not any decent #2 moly or Teflon grease?

Well, moly becomes abrasive when humidity is present. Teflon, I know nothing about. His application is very slow speed, high pressure, hard to form a film. The film needs to be already established by solids and not wiped off. That means solids and some very high Cts oil - over 500 or so. Excavator pins stuff.

Conrad Hoffman · Oct 20, 2017

If the design has reasonable contact areas, the pressure can't be that high. If it's some sort of ball contact, maybe it is. If worried, use the Molykote G-0102. (Molykote doesn't necessarily use moly, it's just a name.) Problems with moly are usually over stated, but I'd never use it in close tolerance bearings or anything where aluminum rubs on something else. A great EP moly grease is the stuff for constant velocity joints. For most general purpose things I use Superlube Teflon grease. I avoid wheel bearing greases because I've had some bad experiences where they harden up like epoxy if not in a sealed system.

AlexO · Oct 20, 2017

Conrad Hoffman said:
If the design has reasonable contact areas, the pressure can't be that high. If it's some sort of ball contact, maybe it is. If worried, use the Molykote G-0102. (Molykote doesn't necessarily use moly, it's just a name.) Problems with moly are usually over stated, but I'd never use it in close tolerance bearings or anything where aluminum rubs on something else. A great EP moly grease is the stuff for constant velocity joints. For most general purpose things I use Superlube Teflon grease. I avoid wheel bearing greases because I've had some bad experiences where they harden up like epoxy if not in a sealed system.

How high the pressures get depends on how the contact surfaces engage - that's a fine point often ignored. Old bearing greases ( the ones which hardened ) were excellent but weren't supposed to be there forever.

Peter. · Oct 20, 2017

For any slow speed high pressure applications I use Molyslip AS/40 grease which has excellent load resisting/anti-galling properties.

We use it to lube the wedges of the concrete splitters at work.

extropic · Oct 20, 2017

I keep the 4oz tubes of the grease (1392K31) and oil (1392K34) on had for your type of application.

McMaster-Carr

cinematechnic · Oct 20, 2017

AlexO said:
Well, moly becomes abrasive when humidity is present.

Interesting, did not know this.

Conrad Hoffman said:
...Problems with moly are usually over stated, but I'd never use it in close tolerance bearings or anything where aluminum rubs on something else...

I used a German-made Moly additive in the engine oil of an older BMW aluminum block/head I-6 engine and saw a reduction in wear metals in subsequent oil analysis reports. BMW's own engine oil has substantial Moly which I think they added to make up for reduced ZDDP (an EP additive that reduces exhaust catalyst life). However, I don't think there are any aluminum rubbing surfaces in a BMW I-6 engine. The cylinder bores have iron liners.

Slightly OT: BMW did TRY Alusil cylinder liners (Aluminum/Silicon) in the '90's with disastrous results. They claimed it was due to excessive sulphur is U.S. gasoline. But the Alusil liners are long gone.

Seems like the Molykote I have on hand is the best choice for this application. It is described as "Brown, calcium complex thickened, mineral oil grease fortified with EP additives" Viscosity 150 cSt @ 40ºC.

BTW, thanks for all the quick replies! I'm putting the post back together today and it's great that I can ask a question and get so many informative answers so quickly. Thanks to all who posted.

AlexO · Oct 20, 2017

cinematechnic said:
Interesting, did not know this.

Seems like the Molykote I have on hand is the best choice for this application. It is described as "Brown, calcium complex thickened, mineral oil grease fortified with EP additives" Viscosity 150 cSt @ 40ºC.

It'll be fine. The right product, name escaped me at the time, is some sort of "assembly paste". You want a very heavy oil - 500cSt or more besides the solid additive.

AlexO · Oct 20, 2017

cinematechnic said:
Interesting, did not know this.

I used a German-made Moly additive in the engine oil of an older BMW aluminum block/head I-6 engine and saw a reduction in wear metals in subsequent oil analysis reports. BMW's own engine oil has substantial Moly which I think they added to make up for reduced ZDDP (an EP additive that reduces exhaust catalyst life). However, I don't think there are any aluminum rubbing surfaces in a BMW I-6 engine. The cylinder bores have iron liners.

Slightly OT: BMW did TRY Alusil cylinder liners (Aluminum/Silicon) in the '90's with disastrous results. They claimed it was due to excessive sulphur is U.S. gasoline. But the Alusil liners are long gone.

Well, not quite OT.

I made a living for quite some time repairing BMW engines. Mostly M5s. Their oil does have a larger amount of MoS2 but they all have now to replace the low Zinc content. The Alusil liners did well enough here - I understood the US diesel gave them the most trouble. But when they switched to Al blocks the things generally went down. In RSA, in the late 80s early 90s speeds were largely unlimited in practice and roads basically empty. The Al engines did not like to be pushed full power for hours - did not like it at all. CI engines, no problem. Heads were another story but I've never seen one crack for no reason. There was a bearing issue in the late 80s but I don't know what the reason for it was.

machtool · Oct 22, 2017

AlexO said:
I made a living for quite some time repairing BMW engines.

Interesting, So your an Auto Mechanic?

AlexO · Oct 22, 2017

machtool said:
Interesting, So your an Auto Mechanic?

No. But I used to race them and I found a niche.

cinematechnic · Oct 24, 2017

AlexO said:
Well, not quite OT.
I made a living for quite some time repairing BMW engines. Mostly M5s...The Al engines did not like to be pushed full power for hours - did not like it at all. CI engines, no problem...

Another "never heard that"... Which generation M5 engines did you work on? I wonder if inadequate cooling was the cause of the problem for Al head/block engines at high speed for extended periods.

The engine I mentioned was a M52TUB28 in an E39. Bought used, it had overheated as most do (due to craptastic recyclable plastic cooling system parts), and had a crack somewhere that was allowing coolant into the oil. So I had to monitor oil condition and work to find the right combination of oil change interval and additives to reduce the wear metals.

The MoS2 really did help with that, as the oil analysis confirmed. I would also add in some high ZDDP oil (Mobil 1 V-Twin) to boost the EP additives. The engine was running well at 180k miles when I sold it. E39's with the I-6 engine are well known to last over 300k mi with proper maintenance.

I don't think any of the new post 2012 BMW's will be lasting that long.

triumph406 · Oct 24, 2017

Use anything you have at hand. the grease you describe finding in the toolpostis probably mineral-oil based high pressure grease.

I would use what I have on the bench, moly axle bearing grease, or better yet Bel-Ray Assembly lube. I would worry more about getting parts done on the lathe than the grease in the toolpost.

AlexO · Oct 24, 2017

cinematechnic said:
Another "never heard that"... Which generation M5 engines did you work on? I wonder if inadequate cooling was the cause of the problem for Al head/block engines at high speed for extended periods.

The engine I mentioned was a M52TUB28 in an E39. Bought used, it had overheated as most do (due to craptastic recyclable plastic cooling system parts), and had a crack somewhere that was allowing coolant into the oil. So I had to monitor oil condition and work to find the right combination of oil change interval and additives to reduce the wear metals.

The MoS2 really did help with that, as the oil analysis confirmed. I would also add in some high ZDDP oil (Mobil 1 V-Twin) to boost the EP additives. The engine was running well at 180k miles when I sold it. E39's with the I-6 engine are well known to last over 300k mi with proper maintenance.

I don't think any of the new post 2012 BMW's will be lasting that long.

Yep, that was a never ending problem. Either expansion tank or water pump packing up ( or belts jumping ) and by the time you knew, it was too late. Funny how they couldn't solve that problem in 20 years. The E39 engine was quite a bit lighter on fuel than the E34's. But the performance was crippled and suffered of a weird and almost unsolvable hesitation at low rpm. But to my mind it was all more than compensated by the body which was far ahead of the E34. Build quality wasn't as good though.

AlexO · Oct 24, 2017

triumph406 said:
Use anything you have at hand. the grease you describe finding in the toolpostis probably mineral-oil based high pressure grease.

I would use what I have on the bench, moly axle bearing grease, or better yet Bel-Ray Assembly lube. I would worry more about getting parts done on the lathe than the grease in the toolpost.

Some people tend to exaggerate maintenance - I do. I like the machines to be as well maintained as I possibly can.

James H Clark · Nov 7, 2017

Personally, I would not recommend any grease, but rather a heavy oil. Grease and lathe chips make a real mess inside confined spaces. That is why grease is not normally used around lathes.

JH

CBlair · Nov 8, 2017

Just a note this thread is really off topic for this forum but I see no reason to move it as the OP has gotten the information desired. In the future please remember that we dont use this section to discuss general or routine maintenance issues. I sometimes let these topics stay if I think it will lead to interesting or useful information. For now I will just close this and let it go.

Charles

Overhauling a KDK Tool Post - What Grease To Use / General Grease Application

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