# External Speed Control on Bench Grinder



## TRN_Diesel (Feb 24, 2009)

I have wanted to buy a bech top grinder and most do not come with a speed control on them so I was thinking why not add an external speed control?

You can buy some for a router is it possible to adapt this to a bench mount grinder?

Has anyone tried this before and had any success?


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## xplorx4 (Dec 1, 2008)

TRN_Diesel said:


> I have wanted to buy a bech top grinder and most do not come with a speed control on them so I was thinking why not add an external speed control?
> 
> You can buy some for a router is it possible to adapt this to a bench mount grinder?
> 
> Has anyone tried this before and had any success?


Good idea, I will give it a try later today.


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## Mike Wingate (Apr 26, 2009)

All grinding wheels have a maximum speed, generally based upon the diameter of the wheel.Slower speed equals cooler grinding. But it takes an instant longer. A slower speed is handy if you change grinding wheels for other rotary devices. All the fixed base grinders that I have used have been single speed.


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## bobj3 (Jan 17, 2006)

Hi Dan

I have and the router control device works but it comes down to what type the motor is...and amps.
Router control device 15 and 20 amp. types.. can be had.
The one I tried was a 15 amp.type..

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TRN_Diesel said:


> I have wanted to buy a bech top grinder and most do not come with a speed control on them so I was thinking why not add an external speed control?
> 
> You can buy some for a router is it possible to adapt this to a bench mount grinder?
> 
> Has anyone tried this before and had any success?


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## TRN_Diesel (Feb 24, 2009)

Thans Jig I assume then if the device (speed adjuster) is rated for 15 or amps you can use it as long as the motor on the grinder does not draw anymore than the rated device. 

I will have to experiment and maybe even try a dimmer switch for a light and see if that works.


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## bobj3 (Jan 17, 2006)

Hi Dan

20 amp speed control below

MLCS router speed control and Foot Switches

The dimmer switch will not work,you will cook in about 2 mins. or so or less .. ,I know you will say they say that it's rated at 15 amps. but it can't take on....it's a very light duty pot..or slider..

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TRN_Diesel said:


> Thans Jig I assume then if the device (speed adjuster) is rated for 15 or amps you can use it as long as the motor on the grinder does not draw anymore than the rated device.
> 
> I will have to experiment and maybe even try a dimmer switch for a light and see if that works.


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## Cassandra (Mar 15, 2006)

TRN_Diesel said:


> Thans Jig I assume then if the device (speed adjuster) is rated for 15 or amps you can use it as long as the motor on the grinder does not draw anymore than the rated device.
> 
> I will have to experiment and maybe even try a dimmer switch for a light and see if that works.


 Hi Dan:

Forget the lamp dimmer switch! As BobJ has said, they won't last. Reason is that the lamp dimmer switches are made for low inductive loads, preferably a resistive load (incandescent lamps.) Motors are high inductive loads, by nature. Current flow in a high inductive load lags the voltage by a significant amount. The lag is something we in electrical engineering call phase angle.

Cassandra


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## TRN_Diesel (Feb 24, 2009)

Ok thanks I learned something today.


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## TRN_Diesel (Feb 24, 2009)

Well after reading and learning thanks to the peopl eon this forum I have come to the realization that it may just be easier to buy a grinder with a variable speed built right into the unit.

The grinders I have looked at are about $60.00 and then you add the variable speed unit and it is over $100 plus shipping.

So Sears has one for $100 with built in speed control :

CRAFTSMAN®/MD 6" 2.8-amp Variable-speed Bench Grinder : Sears Canada

Thanks for all your help it is very much appreciated.


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## crquack (Oct 10, 2008)

Router motors and most bench grinder motors are significantly different. The commercially available speed control for routers will not AFAIK work on a bench grinder.


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## BigJimAK (Mar 13, 2009)

If the grinder has a universal motor, such as a router, it should work. Most grinders have induction motors and they won't like it. If you try it, watch the motor temperature carefully.


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## TRN_Diesel (Feb 24, 2009)

crquack said:


> Router motors and most bench grinder motors are significantly different. The commercially available speed control for routers will not AFAIK work on a bench grinder.


Ok I am going to ask Vana here for a few more vowels so I can figure out what AFAIK means?:sarcastic:


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## Bob N (Oct 12, 2004)

TRN_Diesel said:


> Ok I am going to ask Vana here for a few more vowels so I can figure out what AFAIK means?:sarcastic:




As Far As I Know :dance3:


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