8" bench grinder, switch, there are 3 wires that go to it, what positions are they in ( one is white and appears to be 2 blacks)?

A suppression capacitor has 2 wires and can be have red and black wire pair, and a motor have 2 wires from the electric field to the carbonbrushes and 2 other wires from the magnetfield goes to the switch and on the same wires can be connected a parallell suppresion capacitor connected bud in most cases its not needed in practice.
The other 2 wires have to come from the powercable on the switch the most grinders to find in shops are class 2 angle grinders with double insulation, But If this is an bench grinder there must be a class 1 cable used with 3 wires to earthing a metal point on the housing. look always for the 2 square symbol its class 2 and cable has 2 wires otherwise 3 .

Mmmm... that's a little more complicated. If you have a continuity / resistance meter, we can noodle it out, though.

First, are the two white wires the ONLY wires coming from the motor? I suspect they are - that's not in conformance with any accepted color code, but it'll work. For the rest of this, I'll assume that the two white wires are the only ones from the motor.

You'll need to meter the switch itself, with no wires connected to it. In the OFF position, you shouldn't find continuity between any of the four switch contacts. In the ON position, you should find continuity between two pairs of contacts.

The black wire from the power cord should go to ONE of the two switch contacts in a pair that have continuity with the switch turned ON. One (either) of the white wires from the motor should go to the other switch contact IN THAT PAIR.

That leaves you with one more pair that has continuity with the switch turned ON. The white wire from the power cord goes to one of those, and the second white wire from the motor goes to the other one.

When you have it all wired up, plug it in & turn it on. If it's not right, it should immediately pop your circuit breaker. If it IS right, it should run fine.

If it pops your circuit breaker, open it back up and swap one wire from the power cord and one wire from the motor.

Attach the white wire on your lamp to the white wire on the grinder.
Attache the black wire on your lamp to the black wire on the motor side of the switch.
This will give the lamp power any time the grinder is turned on.
You can put a switch inline of the black wire to the lampp and it will allow you to turn it off when not needed

OR

You can attach the white wires together and the black ones before the switch.
If you choose this way you will need a switch as the lamp will be power all the time.

The neutral line should never be switched--only the hot wire (black). If there are only two wires that went to the switch, you should be able to tie them together and the motor will run when plugged in. The switch should be a common SPST type either toggle or rocker to fit. Hope this helps!

The capacitor goes across the Line, terminals, of the Motor, The Black, should Be Neutral, the RED should be Power IN to the Switch, and the Blue, the "Other" side of the switch. The Capacitor, sometimes goes on the Spare (If any) Terminals of the "Cold" side of the Power Switch.
International color code is Red Positive or Phase, Blue, Phase or Positive, Black, usually Neutral, Negative .
The capacitor is a Suppression" capacitor,and is usually "Across the Motor terminals on "Cold" or "Switched" side of the circuit.
The circuit is simple, Neutral is "Common" the Power comes in to the Switch Contact, whereby the activation of said switch, joins the "Contacts" to the Phase. Positive, Wire to the "Motor". The "Other Terminal Wire from the Motor, goes to Common. The capacitor. Is installed in Parallel with the Phase and Neutral on the "Cold" or normally unpowered side of the circuit.

the two copper tabs under the on off switch are to break the power source.connect incoming power to one of these(black) then a short piece of wire from the other tab under switch to one of the three tabs under plate that is marked hot or l1 is probably #2 but you need to be sure. the white is the nuetral or l2 which is most likely #3 and the green is the ground most likely #4 I would definately look online for a wiring diagram to be sure if they are not marked with L1 L2 and GND

I know this is an old post, but maybe it will help others looking for information.

I have the Craftsman 1/3-HP grinder models: 397.19580 & 397.19581.

They are Split-Phase single voltage (115 V), and use a Klixon start-up current style relay - 2CR14-224.

The relay is normally open. When the large starting current in the main/run winding circuit is sensed by the the relay coil (term 3 & 4) which is in series with the main winding, the relay contacts close (term 2 & 4).

The one end of the start-up winding is connected to the main coil's BLK wire in the coil pack.

When the relay contacts close the start-up winding is energized. The start-up coil is used to provide a boost to over-come the resting inertia of the rotor.

Once the rotor reaches between 65% - 75% of operating speed, the current through the main winding circuit is reduced to the point that the relay coil cannot over come the return-springs force, acting on the relay contact arm. With the contacts open, the start-up winding is no longer energized.

This should take about 2-3 seconds, if the relay malfunctions, the high current through the start-up windings (thin wires) may be damaged.

Here is a diagram I have made.


Klixon 2CR relays are no longer available.

You may find a suitable replacement here:
http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&Product_

Hi again, OK, Well since I don't have a wiring diagram and the colors don't help. I am also going to assume it is 110VAC. The larger wires are probably the run or primary, it you remember which ones were connected it will help with polarizing. ( getting it to run in the right direction as well as the start and primary working together). You can use the two terminal switch but you should use a three wire cord. Use the switch to break the neutral and ground the case. The connections should be as follows: Connection 1, would have one of the primaries and one of the starts to neutral. Connection 2, the other start to the relay. Connection 3, the coil side of the relay to the remaining primary. ( if the relay has two connections on one end and one on the other it would be the single) Connection 4, the 3rd position on the relay to hot. That is how a split phase is wired. You may find a simple wiring diagram on the net if you type split phase motor wiring diagram. Good Luck to you, this should Fixya!

I cleaned all the wiring connectors etc and used a 4-way extension cord with an i/o switch and thermal/arc breaker surge protector thingy. I had a piece of thick cable with a molded three prong plug which I had removed from a dead paper shredder (I think??) and connected the ground to the case (previously not connected) the black to the black and white to the white. I taped the connections and plugged the test cable into the extension thingy with its switch off and plugged it into the wall outlet. Then, with the grinder switch on, I gingerly switched on the extension thingy and the grinder (sans all moving parts) ie just the motor case and spindle (held securely in the B&D workmate) and viola(!) it worked fine and built up to very fast. I switched off the grinder switch and the motor slowed, taking an age to come to rest.
Then, I fitted a grinding wheel on the left hand thread end, tightened everything and retested, using the grinder switch to start it and it spun really fast.
Soooo, I guess the secure ground is an essential feature of a capacitor induction motor. I checked some old furnace motors that were "maturing" in the basement and they had no capacitor but only 2 wires...
I am now trying to remember which parts came off last and put it all back together. I plan to test it each time I put a part back...just in case. I hate it when you fix something on the bench and when rebuilt, it won't work...don't ask about the electric starter on the snowblower..not a happy puppy!
Please, pretty please and then some, do tell me if my "fix" is wrong and I could risk all kinds of nastiness.
Thanks,
Jenni.

Grinding is the fastest way to deburr a sharp corner or dress the end of threaded rod or bar stock that's been cut to length. Fit a grinder with a wire wheel, and you have a handy tool for removing rust. Then switch to a buffing wheel and you're ready to polish metal to a mirrorlike sheen. But for most of us, grinders are essential for shaping and sharpening hardened tool steel and high-speed steel.