21 Aug
2011
21 Aug
'11
1:24 p.m.
I've got a number of fairly high-quality DC fans (Papst, NMB,
Panasonic), some of which are "Smart Fans" that I don't want to lose.
All are plastic construction, not die-cast metal.
I've noticed that on several, the supporting struts between the motor
and frame have developed fractures. I've done some repairs with
epoxy that seem to be holding.
Unfortunately many plastics do degrade with age (oehr factors, such as UV
can speed it up, but they fail anyawy). It's one reason I prefer metal to
plastic (although of course there are metal alloyst htat don;'t last too...)
I've not seen thse fans, but can you strangthen them by taking them apart
and fitting a metal plate overthe end, fixed to the frame and the motor end?
The body of these things seems to be made of some sort of polyamide
(nylon?) with a lot of filler. The usual solvents (e.g. methylene
chloride) don't make a mark, so solvent cement appears to be out of
consideration.
There are plastic glues (not solvents) that are supposed to stick to any
plastics (one even claims to sticl to ptfe!). One of those might make a
stronger repair.
Am I wasting my time with 20 and 30 year old fans? Should I just
scrap the lot and chalk the loss up to age? Experience of others
Only you can decide what your time is worth. I know I'd have ago because
for me, a couple days repairing one is worth less than the \pounds 20
that a new one would cost. Others may differ.
I;'ve enver had this fault in a fan thouhg. Fan faults I've repaired
incldue bad bearings, burnt out windings (yes, I have rewound one) and
power transitor failure on the PCB (fortunately that one used discrete
components, not an IC so it was easy to fix). You may have noticed i
often include a scheamtic of the fan in my HP computer schemeatics...
If a plastic part failed I give serious thought to either replacing it
with metal (not an option here, you don't want to have to make the entire
fan hosuing) or at least strengtheneing it with ametal plate. That's what
I would do here as I suggested above.
-tony