> I can't speak to the motors burning out,
I have several HF electric tools that have performed well for quite a few
years. I really didn't expect the angle grinder to last, as it sounds
hideous, kind of like a buzz saw cutting through a bee hive, but it is still
going strong over 20 years later.
But the first die grinder I got from HF died within seconds. A quick
inspection showed that one of the field wires had gotten tangled in the
rotor. This was not a matter of incorrect break-in or operator abuse;
obviously a manufacturing defect, and clearly the motor had never been
tested.
So IMO it's just the luck of the draw. The designs are OK, materials
marginal; but quality control is totally non-existent. The replacement die
grinder worked just fine.
Oh, and IMO the break-in instructions that were quoted are of questionable
benefit at best. They might possibly contribute to longer brush and/or
commutator life; but brushes are a consumable anyway and I don't recall ever
having an electric motor disabled because the commutator was worn beyond
use. Even worn out brushes are pretty rare in my experience (mostly in 50+
year old equipment, like the original generator on my 56 TR3).
-- Randall
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