"Bob Engelhardt" wrote in message
...
A neighbor has a Festool shop vac, er ... "dust extractor" (at $650,
it wouldn't sell as a "shop vac" G).

It has been shutting itself off due to the motor overheating. It's
spec'ed as using 2.9 - 8.3A (depending upon the speed, I assume).
So I put an ammeter on it and measured 9A, at low speed! Ah-ha,
something to work with. Suspecting a blocked air path was putting
an extra load on it, I first removed the dust bag, then the HEPA
filter, and then took the motor-fan out of the housing. No help: in
free air, at low speed it used 7.4A and at high speed 10A!

The rotor turns easily enough, but doesn't spin when given a push.
The brushes are fine and there is no arcing at the commutator.

So, the only thing that _might_ be an abnormality is the
less-than-free rotor. Could that be the basis for such increased
current (7.5 vs 2.9)? The assembly is not meant to be serviced
(they'll sell you a new motor-fan for $95+). I suppose that I don't
have anything to lose by trying to break it down, but I'd like there
to be something else to try.

Any ideas?

Thanks,
Bob

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