On Thu, 13 Nov 2008 05:39:35 +0000, Ivan Vegvary wrote:

HOWEVER, while running the motor without the gearbox I noticed that it
does not run smoothly. Best I can describe is that it is 'hit and miss'
especially at the low speed. It kind of 'bucks' and 'jerks' while you
cradle it in your hands. The misses get fewer as I speed it up and are
not noticeable at the highest speed.


I don't know what motor you have but I had a brush commutator motor fail
in this way: the rotor wiring was attached to commutator tabs by crimping,
and the crimps were too hard, so many wires broke off. This didn't prevent
the motor from turning, because 1) only some wires were broken and the
inertia pushed the rotor past those dead positions, and 2) each tab was
connected to two poles: one ahead of the tab and one behind. The lower the
speed/current, the harder it was for the rotor to turn, however.

Since I liked the tool and there was no spare available, I picked the area
clean of the potting compound and soldered the wires to the commutator tab.
I am afraid it wasn't a cost-effective activity: if I paid myself $30/hr
I could have bought a new tool, but it was kind-of fun.


--
Przemek Klosowski, Ph.D. przemek.klosowski at gmail