On Sat, 19 Apr 2008 18:16:17 GMT, Bennett Price
""bjpriceNOSPAM\"@NOSPAMcal berkeley.edu" wrote:

I've got a small 12V DC .9 Watt 'muffin' fan (1.75"x1.75"x3/8").
It was the cooler for a video card's processor chip and was
frozen up.

I put a drop of oil into its sleeve bearing and it now runs
reliably - almost. It will start every time as long as it is
not oriented with the open 'face' down. (The open face is the
side in which you can see the bearing). If the open bearing is
down, it sometimes starts and sometimes needs a slight nudge to
get it going.

What's going on? How come? TIA

Realizing that this comes under the heading of "beating a dead horse .
.. ."

Only one continuous long bearing supports the shaft? Some have two
sleeves and you can only see one if you pull the label off - you also
have to pull the shaft completely out.

I've had the same experiences with sintered bearings - the sleeve is
porous and a drop of lube doesn't really do much. The thing worked
for years and has a particles of grunge and a residue of dried oil
filling the lubricating channels in the metal.

If the sleeves can be removed, a cleaning with an ultrasonic cleaner
and some thin petroleum solvent (mindful of the hazards there) will do
wonders if the surface is still round (and if you don't see scoring it
probably is) - then heat the sleeve to 250 F, let it soak at that temp
for an hour, and drop it into lubricating oil to cool to room temp
before replacing.
--


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