Electrical mod to angle grinder

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lada ok
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Electrical mod to angle grinder

Post by lada ok » Mon May 04, 2015 4:16 pm

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

BCjohnny
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Re: Electrical mod to angle grinder

Post by BCjohnny » Mon May 04, 2015 4:20 pm

As it's a brush motor I guess some kind of variable resistor will get it done........
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lada ok
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Re: Electrical mod to angle grinder

Post by lada ok » Mon May 04, 2015 5:02 pm

would that go across the Field or Armature :?:

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Re: Electrical mod to angle grinder

Post by BCjohnny » Mon May 04, 2015 5:14 pm

Well, as they're probably in series, both....
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Re: Electrical mod to angle grinder

Post by joe 90 » Mon May 04, 2015 11:11 pm

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.

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Re: Electrical mod to angle grinder

Post by BCjohnny » Tue May 05, 2015 4:08 am

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.
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Re: Electrical mod to angle grinder

Post by greenhj » Wed May 06, 2015 2:15 am

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.

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Re: Electrical mod to angle grinder

Post by lada ok » Thu May 07, 2015 8:15 pm

Right you are .. I'll check it out

Thanks fellas

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Re: Electrical mod to angle grinder

Post by chevyfreak » Fri May 08, 2015 9:08 am

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.
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Re: Electrical mod to angle grinder

Post by iadr » Sun May 10, 2015 12:22 pm

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.

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Re: Electrical mod to angle grinder

Post by BCjohnny » Sun May 10, 2015 12:52 pm

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 ......
"If an honest man is wrong, after demonstrating that he is wrong, he either stops being wrong or he stops being honest." Anon

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