agree - wood dust from your lathe and sanding - you could try compressed air
to blow the dust out first, that might work - if it doesn't, take it apart
and burnish the contacts with 600 paper and reassemble. Also make sure the
centrifugal mechanism that actuates it moves freely.

If it happens again, spin grinder fast by hand and turn on, it will probably
then just spin up to speed.

"Jim Stewart" wrote in message
...
Michael Koblic wrote:
Things do go pear-shaped in threes: Today I was happily mangling a piece
of wood on my wood-lathe when sharpening became necessary. I turned on my
smaller bench grinder which has a sharpening jig attached. The motor
started to hum but the spindle would not turn. I switched off and turned
the wheel by hand. Smooth as you like. I repeated the procedure three
times with the same result. Possibly a little twitch of the wheel. I
assumed the grinder was gone (Canadian Tire Jobmate, about two years old
and hardly overused. Shame, I actually liked it more than my other
grinder - way quieter). At the end of the session I tried to turn it on
once more and lo and behold, it worked fine! I quickly sharpened all
there was to be sharpened before I switched off.

So the question is: What is the likely cause of this intermittent fault?

Dirty start winding contacts. If you pull it
apart, you'll probably find a spider-like device
on one end of the shaft. It snaps out when the
rotor gets up to speed and by snapping out, it
disconnects the start winding contacts on the
frame. Look for the start contacts and see if
they are burned/corroded/dirty and fix them.