hi,

i've got an old (but still accurate) micrometer from my grandfather.
i cleaned it when i got it (not sure whether that was a good idea) and
now it rubs a little and seems to need a bit of grease/oil. anyone
know the best sort of lubrication to use for a micrometer?

A

-- 
apprentice neanderthal #42
homepage: http://www.physics.adelaide.edu.au/cgi-pschulz/andy-cgi/andyhome
woodpage: http://www.physics.adelaide.edu.au/~awilkins/wood.html

apprentice neanderthal #42 wrote:
>i've got an old (but still accurate) micrometer from my grandfather.
>i cleaned it when i got it (not sure whether that was a good idea) and
>now it rubs a little and seems to need a bit of grease/oil.  anyone
>know the best sort of lubrication to use for a micrometer?
>
I used to repair and calibrate them.  When they didn't need any real repair
for wear, the process was to get everything totally clean and use light oil
on the threads and spindle, lock and rachet, whatever moves.  Just a thin
oil coat.  Clock oil, etc, - or just 3-in-1 won't hurt anything.  

The threads should run _very_ smoothly.  If you feel anything binding it
could still be dirt.  Going beyond that, a common spot for rubbing is the
locking mechanism (if any) not releasing completely.  

The last possibility I can think of is difficult to handle very well without
other equipment available.  The female threads should have an adjustment nut
designed to remove all free play from the thread assembly.  If you have
moved it, it may be set too tight now.  But if you haven't messed with that
adjustment, don't.

Gene

Starrett sells the oil which they use to lubricate their tools at the
factory. I don't know if there is really anything special about it, but
I've considered picking up a can.

Mike
mikef@s...
> 

Andy Wilkins asked what is the best lubricant for micrometers?

        Answer: NONE!

In his response, Eugene gave some valuable information about cleaning and
setting a mic.  But, I disagree with his use of oil - even watch oil.  If
you put a grease or oil onto the mic, there is the strong possibility that
you will use too much - e.g., if you can see the drop of oil you use, it is
too much!  It will then attract/hold small particles over time and make the
mechanism even more cranky.  If fact, the biggest problem I have with old
mics is that they are often "gummed-up" by someone "oiling" them.
        My solution is simple.  I clean the mic, taking it apart if it is
bad enough or if it needs de-rusting.  Make sure there are no burrs in the
threads.  Sometimes I have to use a brass wire brush on the threads to get
out the stuff glued to them by oil aging.  (Eugenes comment needs repeating
here about the threads - "The female threads should have an adjustment nut
designed to remove all free play from the thread assembly.  If you have
moved it, it may be set too tight now.  But if you haven't messed with that
adjustment, don't."
        Sometimes, without disassembly, all I need to do is to repeatedly
and heavily spray a penetrant or even WD-40 into the mic, working it's
mechanism to clean it - and leaving enough "oil" residue from the cleaner.
        One trick I learned at the Starrett factory in Athol Mass, when
they let me clean and repair a dial indicator - I was told by the repair
person that their precision mechanisms have NO oil on their moving parts
other than that left by the machining process lubricants  - was to use
lacquer thinner as the final cleaning agent.  In fact, a
minute/tiny/miniscule drop of the thinner on a dial indicator shaft can
work wonders for a sticky dial.
        So, my advice - works for me - do not lubricate your mic.  Clean it
and keep it clean, dry and away from "salty' fingers.

        
*****************************************
*	Karl W. Sanger			*
*					*
*	Desperately seeking antique	*
*	Machinist Tools!!!		*
*					*
*	Email: sangerkw@m...	*
*****************************************

Karl W. Sanger wrote:

>         My solution is simple.  I clean the mic, taking it apart if it is
> bad enough or if it needs de-rusting.  Make sure there are no burrs in the
> threads.  Sometimes I have to use a brass wire brush on the threads to get
> out the stuff glued to them by oil aging.  (Eugenes comment needs repeating
> here about the threads - "The female threads should have an adjustment nut
> designed to remove all free play from the thread assembly.  If you have
> moved it, it may be set too tight now.  But if you haven't messed with that
> adjustment, don't."

What can be done to a mic that has been worn excessively in a range -
say between 1/4 and 1/2".  Tightening the adjustment nut will only make
it stick in the unworn spots.  Is there some nifty trick to resizing the
threads or should it be relagated to the C-clamp pile?

Garrett

Garrett asked:
>What can be done to a mic that has been worn excessively in a range -
>say between 1/4 and 1/2".  Tightening the adjustment nut will only make
>it stick in the unworn spots.  Is there some nifty trick to resizing the
>threads or should it be relagated to the C-clamp pile?
>
As far as I know, it's a c-clamp.  We used to have more fun with them than
that.  Borrow someone's mic, switch them, and when handing it back, drop it
on the concrete. (Just don't get them mixed up when doing that)

Gene