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Electrical mod to angle grinder

Posted: Mon May 04, 2015 4:16 pm
by lada ok
I want to be able to slow the speed of a 230 v / 50 htz angle grinder & even maybe variable speed as well.
How can I do it fairly simply, .. can I add a variable resistor / similar in the circuit :?:
The m/c won't be under a big load, and it would be good not to have to larger tq loss at ow rpm

Re: Electrical mod to angle grinder

Posted: Mon May 04, 2015 4:20 pm
by BCjohnny
As it's a brush motor I guess some kind of variable resistor will get it done........

Re: Electrical mod to angle grinder

Posted: Mon May 04, 2015 5:02 pm
by lada ok
would that go across the Field or Armature :?:

Re: Electrical mod to angle grinder

Posted: Mon May 04, 2015 5:14 pm
by BCjohnny
Well, as they're probably in series, both....

Re: Electrical mod to angle grinder

Posted: Mon May 04, 2015 11:11 pm
by joe 90
Use a variac.
It's a transformer with variable voltage output.
They might be a bit hard to get hold of(I've got 2).
Another option would be a light dimmer controller (triac), one for normal old style light bulbs....try jaycar.
A variable resistor would probably burn up.

Re: Electrical mod to angle grinder

Posted: Tue May 05, 2015 4:08 am
by BCjohnny
Yes, correct.

Old style dimmer switches were variable resistors, modern ones aren't, but haven't got out of the habit of referring to them as such.

Re: Electrical mod to angle grinder

Posted: Wed May 06, 2015 2:15 am
by greenhj
Jaycar offer a sweet DIY speed controller that I've successfully used with electric die grinders, minimal loss of torque at low speeds, its a bit cumbersome but it does it's job well.

Re: Electrical mod to angle grinder

Posted: Thu May 07, 2015 8:15 pm
by lada ok
Right you are .. I'll check it out

Thanks fellas

Re: Electrical mod to angle grinder

Posted: Fri May 08, 2015 9:08 am
by chevyfreak
Depending on what you want to do with slower speed , a polisher(grinder type) can also be used. They have less power but also turn slower.
cheers
chevyfreak.

Re: Electrical mod to angle grinder

Posted: Sun May 10, 2015 12:22 pm
by iadr
BCjohnny wrote:Yes, correct.

Old style dimmer switches were variable resistors, modern ones aren't, but haven't got out of the habit of referring to them as such.

All the ones I've seen until within the last 10 years (Canada, btw, so 110V) simply cut a section out of the sine wave...hence the great loss of torque when used inline with a tool. I wouldn't call that a resistor, per se... Not sure what it is called.

Re: Electrical mod to angle grinder

Posted: Sun May 10, 2015 12:52 pm
by BCjohnny
TBH I've never bothered to find out how the newer ones work.

I've got a couple of Variacs, one 8a and one 16a, and as stated are the best way to get it done, but they are usually a lot more expensive, even s/h, than the actual grinder used, and can be thin on the ground. The 'overdrive' can be useful ......