[GreenKeys] Grease

[Roy Morgan]

At 12:32 PM 10/21/2007, you wrote:
>... the lithium grease I sprayed on there seemed to have little or no 
>persistency....i.e. not much lube there.

Larry and other Greenkeyers,

I just overhauled the gearbox on a receiver and found similar conditions: 
the original grease used 50 years ago in the bearing cups was in better 
shape than what might have been Lubriplate applied much more recently.

>I'm headed down to the auto parts store to get some real grease

Maybe you came back with "One Grease" made by the Slik 50 people. That's 
what I used in this radio. I figure it's good "for the duration" now. That 
stuff has Teflon in it.  The complimentary "One Lube" is liquid in a spray 
can.  I have not found "One Lube" in non-spray containers, but I can spray 
in into other containers if I need small quantities.

>and now I guess I'll have to do all the machines that I originally so 
>brilliantly did with lithium spray on grease....damn!

I recommend it.  The "What grease should I use?" question is one of those 
dead horses we beat from time to time.  I have an M-15 motor here that is 
new in the box, but I can't move the shaft for the grease coagulation.  The 
thing may well be 60 years old! Of course it has to come apart for thorough 
cleaning and re-greasing if I am to use it in the future.

Here are some tips I can remember (some mine, many from other folks):

- Never use high pressure compressed air to dry out a cleaned bearing - it 
can spin the thing up so fast as to damage it.

- Don't use gasoline to clean bearings.. too dangerous.  Kerosene, brake 
cleaner, or Varsol is better.  (Varsol is still available, but apparently 
in large quantities.  Varsol comes in a variety of mixtures for different 
uses, too just like Glyptal.)

- If you use WD-40, use it  only for cleaning. It is apparently made (now) 
from mostly refined kerosene (Stoddards Solvent) and a bit of light oil. It 
will not lubricate anything for long. Clean it off completely before 
applying a good lubricant.

- The people who might sell you bearings would have both advice and grease 
for you.  Grease that's good for a 3600 rpm motor is likely not good for a 
10,000 rpm Dremel motor tool or router.  Bike shops also have grease.  I 
got one tube from a bike shop that's a bit shorter than a toothpaste tube: 
it's touted as being waterproof, will last until contaminated with dirt, 
and ideal for bicycle wheel bearings.

- Bell System and army manuals on teletype machines talk about using grease 
in motor bearings at cleaning/overhaul time then using oil later on at 
maintenance intervals. It seems to me that good modern grease installed 
right should last for a LONG time in amateur intermittent service.

- As you take a Teletype motor apart, NOTICE THE POSITION OF ALL SHIMS, and 
put them back exactly as you found them.  I had to dis-assemble one motor I 
did because it would not turn freely upon re-assembly. Apparently, I'd 
moved a shim from inside to outside of the bearing because it looked right, 
not because it was right.

- Don't over grease a motor that has a governor or commutator.  The grease 
can fly into the electrical parts and cause trouble.  Automotive brake 
cleaner is good for removing grease and oil from governors and commutators.

- Check a motor once it's been run to operating temperature for free 
operation.. The heat can cause the bearing clearance to close up and bind.

- In normal use (continuous, with periodic maintenance) teletype machines 
got moderately oily.  It seems to me that this was good. Every nut and bolt 
was covered in a light film of oil. If we keep our machines cleaner than 
that or if we clean things well at overhaul time, a bit of grease on the 
threads of nuts and bolts will do well.  Most Teletype machine hardware has 
threads that are finer than other machines (at least American ones) that we 
deal with.  So greased threads tightened with less torque than we are used 
to will do fine.

- If you come across a bearing that seems to be a bit rough, write down any 
numbers you find on it, grease it carefully and put it back into operation 
with a  tad more than normal play.  It may last forever that way.  Or you 
may find that a modest investment in new bearings is a good thing.

- As I set the shaft play in the radio I just finished, I found that as I 
tightened the bearing cups or the shaft-end single bearing adjustment, I 
could hear and feel the the bearing as I reduced the play and wiggled the 
shaft. A little more tightness and  I could not hear it any more, but I 
could feel it.  THAT is where I'd set the end play.  If I tightened just a 
bit more, I could not feel it any more and the shaft would not spin easily: 
that was too tight.

- A teletype motor of the old sort has a lot of metal in the armature 
compared to modern motors.  A strong spin on the shaft or pinion should set 
it to turning for many turns if its bearings are well lubed and happy in 
end play.

Happy greasing, and may your well-lubricated machines last longer than any 
of us!

Roy




- Roy Morgan
National Institute of Standards and Technology
100 Bureau Drive, Stop 8970
Gaithersburg  MD 20899-8970
Voice: 301-975-3254  Fax: 301-975-6097
E-mail:  roy.morgan at nist.gov --