[sci.electronics] Maint. of Elec. Motors

rrw@naucse.UUCP (Robert Wier) (09/29/89)

 I'm not sure if this is the right newsgroup, but...

 Can anyone tell me why it is that small fractional horsepower
 electric motors eventually sieze up and stall after a few months
 of usage.

 What I'm basically thinking of are small tabletop fans of the
 6" to 24" size.  It seems they all run fine for 4 or 5 months,
 and then start more and more slowly.  If you let them just sit
 and hum, they will ususally start up.

 I've disassembled a bunch of these guys, and they usually have
 accumulated some junk on the bearings (assuming they have
 bearings...some dont).  If you clean them off, and lube them a
 bit they will work fine for a few weeks, and then they start
 having the same problem again.

 I've tried everything from no lube, to wd 40, to teflon based
 oils with no success.  Strangely enough, no lube seems to work
 as well as anything.  Putting lube on there just seems to attract
 dust.  

 What causes this.  Are they so cheaply made that the frame warps,
 making it impossible to get the rotor to turn freely?  I'm assuming
 that letting the current run through them when they've stalled 
 heats something up (either the "bearing") or the lube, giving
 enough clearance that they will then run.  I'm nervous about
 doing this because of the fire danger.

 Any suggestions?

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  - Bob Wier                             Northern Arizona University
   Ouray, Colorado            &                Flagstaff, Arizona
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