[Rob Keller]

I was wondering if there is a way to slow down my electric grinders.

maybe a rheostats?{if I got the right word}

I use the grinders with wire wheels to clean up grease and rusty stuff & some times they are just spinning WAY too fast.

Can this be done safely?
Can this hurt the tool?
Running it too slow or something?

[matt167]

use a router speed control. heavy duty light dimmer switch is all they are. HF sells them

[123pugsy]

Originally Posted by matt167

use a router speed control. heavy duty light dimmer switch is all they are. HF sells them

I bought one before and found it doesn't work on all motors.

[Rob Keller]

Originally Posted by 123pugsy

I bought one before and found it doesn't work on all motors.

What Happened?

[Vortech 4.3]

i use one on my craftsman electric die grinder. it works great.

[123pugsy]

Originally Posted by Rob Keller

What Happened?

It was a couple of years ago so my memory is a bit fuzzy, but I know it didn't work on my router so I tried it on an electric drill or something else just for the heck of it. Well of course with my luck it worked on a tool with a built in speed control on the switch and not on the tool I needed it for.

[Rob Keller]

Thank you All Very much

pugsy123 ~

Yes sir.
I am familiar with that type of end case scenario.

I would have know this if I ever did any kind of Fine wood working
Other than Flooring



Thanks


Rob

[oldred]

On an AC motor it is not as simple as cutting down the voltage and if you do that it will cause the motor to overheat. A DC motor will run fine on lower voltage and that is why DC is used when a variable speed motor is called for on most machinery. An AC motor speed controller, although fairly simple, is quite a bit more than just a light dimmer which is nothing more than a rheostat and a light dimmer should never be used to control the speed on an AC motor, it can cause damage to the motor. I have one of those HF motor controllers and although it will reduce speed it also reduces the power a LOT.

[cboy]

So are the HR controllers for AC or DC?

[Henry Highrise]

I have used a router speed control with my 2 and a half horse power router for years...never had a problem with it...yes the motor is AC. I did not use a HF controller though...I got mine at Sears. I have never tried to slow down a grinder with it...but I don't see why it would not work for that.

[oldred]

Originally Posted by Henry Highrise

I have used a router speed control with my 2 and a half horse power router for years...never had a problem with it...yes the motor is AC. I did not use a HF controller though...I got mine at Sears. I have never tried to slow down a grinder with it...but I don't see why it would not work for that.

Nothing wrong with that, it is for an AC motor and should work with most tools as long as they don't exceed the rated current on the speed controller.

The Harbor Freight speed controller is for AC use also and will work with most AC motors but if you open up either one of these controllers you find that it is a heck of a lot more than just a simple rheostat. Using a light dimmer (which appears to be a rheostat) would be no different than using an extension cord that is too long which will cause a voltage drop and can damage an AC motor.

[fitzwell]

Foot control off a sewing machine?

[oldred]

Originally Posted by fitzwell

Foot control off a sewing machine?

I think those things use a DC motor, I think anyway?

That little outfit from HF works pretty good and I use mine a lot, well I did anyway until I closed a door on it and broke the dang thing. I think they are on sale right now for about 10 or 12 bucks so I am going to get another one, they will handle some pretty big stuff and I found mine to be especially useful for my electric die grinder.

[scrot]

Doc is rolling over in his grave now.

The light dimmer for an AC circuit is a lot more complicated than a rheostat. Ever heard of an S.C.R., silicon controlled rectifier?
It clips off part of the AC sine wave to reduce the power.
Doc , we need you back!

[cboy]

Originally Posted by scrot

Doc is rolling over in his grave now.

And saying, "Sheesh, heaven...where's my wireless connectivity so I can straighten those guys out."