what's wrong with my Bench Grinder?

[jkn]

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

[Andrew Gabriel]

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.

[Clive Mitchell]

In message , jkn writes

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.

[jkn]

Hi Andrew

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

[Andrew Gabriel]

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

[jkn]

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

[jkn]

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

Jon N