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?

Thanks,

--
Michael Koblic
Campbell River, BC

PS I am not going to ask about the washing machine! The printer started
smoking when I was printing out the service manual :-)

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.

Jim Stewart wrote:
Dirty start winding contacts. If you pull it
apart, you'll probably find a spider-like device
on one end of the shaft. ...

Almost certainly true. But be careful when pulling it apart - bending
the spider's legs will put it out of adjustment. In which case the
contacts may never close or never open.

Bob

On Tue, 10 Nov 2009 18:15:11 -0800, "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?

Thanks,

1. Bad switch
2. Marginal connections to start cap
3. dirty inboard startup switch

4. Bad outlet.

If it happens again..check #4 first..then work your way down the list

Gunner

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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.

"Bill Noble" wrote in message
...
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.

That reminds me of the homemade wood lathe someone gave me when I was in
high school. It had the only electric motor in town with a rope starter. You
had to make sure the rope was completely unwound and clear before throwing
the switch. g

--
Ed Huntress



"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.

"Bill Noble" wrote in
:

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.

It's been so long I can't remember where it was, but someplace I
frequented (friends shop?) had a grinder like this. You got used to
giving the wheel a flick before hitting the switch, and off it went.
Fixing it properly had been on his "to do" list for years, but the time
it took to flick it into motion seemed so trivial compared to the time to
tear it down & fix it that the owner never bothered. It's probably still
like that if he's still around.

Doug White

"Bill Noble" wrote:

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.

I'd try burnishing with a crisp dollar bill held between the contacts first.

Wes

On Wed, 11 Nov 2009 15:14:58 GMT, Doug White
wrote:

"Bill Noble" wrote in
:

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.

It's been so long I can't remember where it was, but someplace I
frequented (friends shop?) had a grinder like this. You got used to
giving the wheel a flick before hitting the switch, and off it went.
Fixing it properly had been on his "to do" list for years, but the time
it took to flick it into motion seemed so trivial compared to the time to
tear it down & fix it that the owner never bothered. It's probably still
like that if he's still around.

Doug White
Similar to a friend's printing press - flip the switch and roll the
big flywheel. I seriously doubt that the little 1/4 HP washing machine
motor could have got that thing rolling from dead stop even with the
start winding helping!
Gerry :-)}
London, Canada

On Tue, 10 Nov 2009 21:00:23 -0800, "Bill Noble"
wrote:

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

I have a buffer like that. 2 HP, 120V 3450 RPM single phase motor. It
actually can self-start, but when doing so it draws peak current of
195 amps for part of a second. Sometimes the 20 amp breaker can
ignore that, sometimes it can't. I just give the wheel a brisk spin
before hitting the green button.

On Wed, 11 Nov 2009 20:16:17 -0500, Gerald Miller
wrote:

On Wed, 11 Nov 2009 15:14:58 GMT, Doug White
wrote:

"Bill Noble" wrote in
:

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.

It's been so long I can't remember where it was, but someplace I
frequented (friends shop?) had a grinder like this. You got used to
giving the wheel a flick before hitting the switch, and off it went.
Fixing it properly had been on his "to do" list for years, but the time
it took to flick it into motion seemed so trivial compared to the time to
tear it down & fix it that the owner never bothered. It's probably still
like that if he's still around.

Doug White

Similar to a friend's printing press - flip the switch and roll the
big flywheel. I seriously doubt that the little 1/4 HP washing machine
motor could have got that thing rolling from dead stop even with the
start winding helping!
Gerry :-)}
London, Canada

I think you just answered your own question - The little motor
couldn't get it rolling from a dead stop. Without the start winding
you have to get a motor spinning pretty fast for the Run winding alone
to get it moving, and that with no load like a radial arm saw.

I think the little Chief 15's came with a 3/4 HP motor. When I was
young and foolish I thought they were overpowered for what they were,
then I sat down and thought about it.

With the large flywheel mass and all the friction points on an
offset press (all the damper rollers and ink system rollers, the
friction caused by the blanket, the in-feed and out-feed mechanisms,
etc.) all being run by that one motor, 1/4 HP wouldn't have a chance
without a hand-spin.

Go ask the friend - Betcha the old motor died, and he had that little
one on hand. And "it worked" so he never bothered.

-- Bruce --