Failed angle grinder

[Lobster]

Yes it's the dreaded Screwfix 'Kinzo' job at £2.47...

Now don't give me a hard time for buying it - "what do you expect for £2.47" etc etc; I know all about that, and that's not why I'm posting this!

Just that I'm curious as to the failure mode. This is the second of these that's died on me in the same way (and the last, as Sfix have stopped stocking it!). I was using it today, under pretty light conditions; went off for a cuppa and when I came back it was dead a doornail. Same thing last time - I took it out of the cupboard, switched on: nothing, zip, nada, rien. Tried manually rotating the motor a bit and tried again; fuse was OK, bushes intact, but it's definitely dead.

Why amd how would a motor fail like that, ie, when not being used?

David

[Grunff]

Heat soak. The cheapies are very prone to it because of poor cooling design. They run pretty hot when running, but the fan just about stops them from burning out.

[Capitol]

Is it the switch which has failed? Most of the cheap units have crappy switches. If you can get it apart, it may be that the contacts are not, due to dust in the switch.

Regards Capitol

[Mary Fisher]

Where do you buy ANYTHING for £2.47???

It should have been £2.99.

Mary

[John Stumbles]

Yes, my first one failed like that - just one pole of the switch not closing. If I come across any Round Tuits I might bypass the built-in switch and wire an external one into the cable. Mind you mine was one of the expensive (£6.99) ones - a switch to repair yours would probably cost £2.99 :-)

[andrewpreece]

I have a flat bed tilecutter, in fact I've had three, and all failed mysteriously. I took the first two from MachineMart back, but then bought one from Wickes and that one failed too!

I took it apart in a fit of pique and found that the field winding of the motor had a series thermal fuse. Rather shortsightedly, the designers had made it a single use device instead of a bimetallic resettable device. In fact I had been working the cutters hard and the windings got so hot they melted the thermal fuse - end of story! At least one of the tilecutters went dead whilst I was resting it between tiles, and I think that the heat takes a little while to melt the fuse.

If you're bothered, you can try and disassemble your grinder, and have a look at the field winding ( there may be fibreglass tape hiding stuff ). If you see a small metallic leaded can in the winding, that's probably a failed thermal fuse. If you take it out and connect the remaining two ends of field winding together again it'll probably work. WARNING: You must stabilise and insulate the repaired winding adequately, and you will have no thermal protection in future so it's slightly dodgy. I only give my tilecutter light use nowadays.

Andy.

[Tim Lamb]

In article , Grunff writes

Run off load for a few seconds before disconnecting. Cautiously waggling some fingers in the exhaust air should indicate how long.

Somebody will know the safe working temperature for the *between turns* winding insulation:-)

regards

[Dave Plowman (News)]

Yes, my original Plasplugs one did this while out on loan. I'd neglected to pass on the instructions about duty cycle. However, I've never had a problem myself, as I've not wanted to cut batches of tiles - I'll usually do one at a time, and switch off between. I also prefer to use it outdoors clamped to my Workmate, which may help with cooling.

Maplin stocked the correct replacement thermal fuse.