Variable speed controller...

It says it works with any motor 15 amps or less, but I don't know. If I knew for sure I wouldn't burn up my Griz I'd get one.
 
Nope..... been there..... tried that..... variable speed conversions are expensive for a reason..... sucks.


You will lose ALL torque with one of those switches.


Rick
 
Somewhere on the motor for your grinder, there should be a plate that lists its power needs. If it says that its a 120V DC motor, and assuming that all you want is some speed control on your grinder, you might want to think about just wiring in a dimmer switch to whatever wall socket your grinder is pluged into. A couple of paint markers to mark graduations on the dimmer switch, and you'll get something just as good as what you're looking at, just a lot cheaper and easier to replace. Thats how I rigged up the blower on my forge, and it works great.
 
I hope you meant 120V AC/DC.....If you wire a 120V DC motor to an AC outlet it will become scrap metal.
Stacy
 
bladsmth said:
I hope you meant 120V AC/DC.....If you wire a 120V DC motor to an AC outlet it will become scrap metal.
Stacy
Click to expand...

Nooo.. I meant 120V DC. The standard voltage and current flow used in the US. AC is how they send the electricity over the power lines, but a transformer changes it from AC to DC. I don't think I've ever even heard of an AC outlet here in the US. Besides, the point is moot. That controller is a DC controller, little more than a dimmer switch that came prepackaged. It is slightly heavier duty, 250V DC max, but, unless you have a supper powerful 240V motor, you don't need it. If its just a 120V, buying the dimmer switch is cheaper. The controler does come with a fuse to prevent surges from destroying a router from burning up, but a grinder motor most likely has one already installed. Like I said, check the plate on the side of the motor. That should tell you the voltage requirements.
 
I bought that exact router speed control to use on my Craftsman 2 x 42 grinder and it failed miserably. It doesn't even come close to working. You have to turn the dial control 3/4 of the way up to get the grinder to even start, and when it did, there was no speed control AT ALL, and it bogged down as soon as a blade even touched it.
 
thompsonblades said:
Nooo.. I meant 120V DC. The standard voltage and current flow used in the US. AC is how they send the electricity over the power lines, but a transformer changes it from AC to DC. I don't think I've ever even heard of an AC outlet here in the US.
Click to expand...

Wow..... just wow... still living in 1887, I see...... lol.

I didn't even feel the need to look that one up.
 
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The USA hasn't used DC current as a standard since Thomas Edison lost the AC/DC battle against George Westinghouse. By 1900 there were few places using DC. As far as I know the last US holdouts stopped using DC current when I was a young boy in the 60's. Most of the world had stopped by WWII.

The USA transmitted power is all AC - Alternating Current, at 60 cycles per second. A transformer only lowers (or raises) the voltage. A rectifier could change the voltage from AC to DC, but there are no rectifiers in your power system.
The power is generated at the power plant, and sent down the main lines at around 330,000 volts AC ( voltages I am using are one of many combinations). This is reduced by transformers to 33,000 and then 3,300 volts as it goes around town. At the telephone poles on your street, the transformers reduce it to 110/120 volts AC. Usually two phases are sent to your house, thus allowing 240VAC to be used for heavier amperage equipment , and 120VAC for normal things.

Stacy
 
I use one on my custom 7" angle grinder setup but I'm with the others if you mean for a knife grinder.

I only use it for speed control when using sanding/scotch-brite discs, for grinding and cutting I run full speed..

frankengrinder_1.JPG


frankengrinder_2.JPG
 
bladsmth said:
The USA hasn't used DC current as a standard since Thomas Edison lost the AC/DC battle against George Westinghouse. By 1900 there were few places using DC. As far as I know the last US holdouts stopped using DC current when I was a young boy in the 60's. Most of the world had stopped by WWII.

The USA transmitted power is all AC - Alternating Current, at 60 cycles per second. A transformer only lowers (or raises) the voltage. A rectifier could change the voltage from AC to DC, but there are no rectifiers in your power system.
The power is generated at the power plant, and sent down the main lines at around 330,000 volts AC ( voltages I am using are one of many combinations). This is reduced by transformers to 33,000 and then 3,300 volts as it goes around town. At the telephone poles on your street, the transformers reduce it to 110/120 volts AC. Usually two phases are sent to your house, thus allowing 240VAC to be used for heavier amperage equipment , and 120VAC for normal things.

Stacy
Click to expand...

Since we're dealing with a thread and trying to remove some serious misinformation from a previous poster I just want to make one note about your post Stacy.

99% of residential dwellings get single phase power. They get a Neutral line, and 2 hot lines. Neutral is reference for single phase 120VAC. Power from a hot line to neutral is 120VAC 60Hz. Power from one hot line to the other hot line is 240VAC. Generally 120VAC come in 15A or 20A flavors. 240VAC outlets start at 15A but generally 20A and can reach 50A or greater.

Power hungry devices, such as motors and heaters often draw from high current 240VAC lines.

And as it's been said DC is not a currently used means of carrying current long range.

A variable speed motor must either be 3 phase AC, 1PH or 3PH DC, and AC/DC.

THe only viable way to run a grinder variable speed is with a properly sized 3PH AC motor and a driver to run it off 1PH household current.

Other motors can be run via speed control, but lose any torque the posses. If you lack funds to get a proper speed control setup, learn to grind at high speeds, then when you sell knives and make money buy a nice variable speed setup. :thumbup:
 
bladsmth said:
Those only work on AD/DC brush motors.
Stacy
Click to expand...

This is true

Notice on this example posted above, the little black circles beside the word Makita- are the screws that cover the brushes; hence brush motors.

The "normal" AC motors used in fractional horsepower motors use no brushes.

frankengrinder_1.JPG


and Thompsonblades, you are completely misinformed on this whole AC/DC thing
 
Thanks for the catch.
Yes, that was worded confusingly.The use of the words TWO PHASES creates the confusion. The better wording would have been "TWO LEGS" or TWO LINES.

The three wires coming to most houses from the transformer are two hot lines and a ground. The 240 volt step down transformer is center tapped to the ground line.The two 120 volt wires are thus phased 180 degrees from each other. They are on the same "phase" of the three phases created by the generator at the power plant, but are phased 180 degrees apart from each other by the center tapped transformer. This allows them to reference to each other as 240VAC or reference to ground at 120VAC. It makes perfect sense on an oscilloscope.

We won't get into the fact that our voltage is actually 170 volts, but the RMS is 120 volts......
Stacy

Here is a good explaination of the whole thing:
http://www.howstuffworks.com/power.htm/printable
 
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