[time-nuts] Fan for old HP synthesizer

[Chuck Harris]

Assuming that the steel shaft hasn't worn to a smaller size
(the usual cause of failure in a oilite bearing, here is how
you re lubricate the beasts:

1) disassemble and clean in naptha (lighter fluid) use a string,
    or small brush to clean the bearing hole in the oilite.
2) heat the bearing until it is too hot to touch, but not smoking
    hot.  Wipe off the oil that appears.  Drop hot bearing into a
    puddle of oil, and let it cool.  The bearing will soak up the oil
    as it cools.
3) reassemble.
4) re oil any oil felts that might exist.

Usually, though, when the oilite runs out of oil, it grinds (polishes)
away the shaft, and in doing so increases the clearance so that the
shaft doesn't draw out the protective oil film that provides the
lubrication.  The rumbling of the shaft in the excess clearance also
tends to hammer the pores in the oilite closed, so they nolonger can
allow oil to wick onto the bearing surfaces.  Adding oil will work for
a very short while, but ultimately, the bearing gap is too wide, and
the oil will be flung away.

-Chuck Harris

David Forbes wrote:
> I realize it's a bit off topic, but not too far, as keeping old HP 
> stuff alive is a significant fraction of time-nuts activity.
> 
> Our telescope uses several old HP 8672A 2-18 GHz synthesizers. These 
> beasts use a bizarre fan made by IMC that is basically the inside of a 
> muffin fan mounted on four rubber vibration isolators.
> 
> The sleeve bearings only last 20 years or so in the dry air-starved 
> environment at 10,000 feet altitude, and we just had one grind to a 
> halt last week. I cleaned it and added oil, but this is a stopgap 
> measure as I don't have the ability to really soak the oilite bearing 
> in oil.
> 
> The fan model is SWS2107FL-51, HP part number 3160-0296. Google 
> reveals nothing but the sites with lists of every part ever made.
> 
> Does anyone know of a replacement fan for these machines?
> 
> Or does anyone have good re-lubrication tips?
> 
> Thanks in advance for your help.
> 
> 
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