Hi all
my (extremely cheap) Bench Grinder stopped working a little while
ago. Switching the on switch just gives a little 'kick' to the wheels,
nothing more. I've replaced the Capacitor (4uF 450V) but nothing has
changed. I'm a bit surprised given that the motor is an induction
motor - is there anything to go wrong which might be causing this
symptom?

On a slightly different note, any suggestions as to where I can get a
cheap grinding wheel (150mm x 12mm or so) which has a finer abrasive
than 60 or so?

Thanks
Jon N

In article . com,
"jkn" writes:
Hi all
my (extremely cheap) Bench Grinder stopped working a little while
ago. Switching the on switch just gives a little 'kick' to the wheels,
nothing more. I've replaced the Capacitor (4uF 450V) but nothing has
changed. I'm a bit surprised given that the motor is an induction
motor - is there anything to go wrong which might be causing this
symptom?

Depends on the type of induction motor. One winding burned out might.
If you spin it by hand and then plug it in whilst it's still spinning
(with hands well clear), does it run? If it does, beware it will run
in either direction (depending on which way you spin it), so make
sure you spin it the right way.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In message . com, jkn
writes
my (extremely cheap) Bench Grinder stopped working a little while
ago. Switching the on switch just gives a little 'kick' to the wheels,
nothing more. I've replaced the Capacitor (4uF 450V) but nothing has
changed. I'm a bit surprised given that the motor is an induction motor
- is there anything to go wrong which might be causing this symptom?

Sounds like it may be the switch itself that's knackered. You could
find this out by unplugging the grinder, bridging the switch contacts
then plugging it back in and seeing if it starts immediately.

If it does then post a link to a picture of the switch and we'll see if
we can suggest a source of a replacement for you.

As always take the usual safety precautions. An uncle of mine suddenly
decided he stopped wanting to tinker with electrical gear when he had a
"gripping" experience with a bench grinder.

--
Clive Mitchell
http://www.bigclive.com

Hi Andrew

Depends on the type of induction motor. One winding burned out might.
If you spin it by hand and then plug it in whilst it's still spinning
(with hands well clear), does it run? If it does, beware it will run
in either direction (depending on which way you spin it), so make
sure you spin it the right way.

Thanks - I tried this with no success, but I wasn't spinning it very
fast at all. I'll give this another go tomorrow.

It did occur to me just as I posted that it might just be the switch.
I'll check that as well. I'm sure I could find another one to suit if
need be.

Rest assured I will take precautions - this is one of the power tools
I am most wary of. 1/2 I omega_squared and all that ...

Thanks
Jon N

In article .com,
"jkn" writes:
Hi Andrew

Depends on the type of induction motor. One winding burned out might.
If you spin it by hand and then plug it in whilst it's still spinning
(with hands well clear), does it run? If it does, beware it will run
in either direction (depending on which way you spin it), so make
sure you spin it the right way.

Thanks - I tried this with no success, but I wasn't spinning it very
fast at all. I'll give this another go tomorrow.

No don't -- it didn't need to be spinning fast to check out
this theory.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Followup - I checked the switch this morning and it looks like one
pole has gone O/C. Damn - I'm annoyed I didn't check this first. The
'kick' the motor gave fooled me.

Cheers
Jon N

Followup - it was indeed the switch. Damn. The 'kick' on switch-on
blinded me to the alternatives. A salutary lesson...

Jon N