I OWN A OLDER SEARS GRINDER. I JUST QUIT ON ME . THE WHEELS TURN FREELY SO I BELIEVE IT IS JUST A RELAY. THE NUMBER ON THE RELAY IS ( 4CR-20-728 ). DO YOU KNOW WHERE I CAN BUY ONE.

A grinder that growls when you start it usually means the bearings are worn out or very dry. You can try a little WD40 spray in the bearing area and if that seems to work use some heavier oil to keep it running. It's good to oil the bearings every so often I find.

I need a 4CR-20-756 Klixon relay for a bench grinder.

when i turn on switch it just humms. 1/2 hp older model

Remove the bean hopper and vac out all beans, then remove black cover, then 3 phillips screws, and top part of burrs should come off. Clean our chamber then reassemble. DO NOT TURN ON. Make sure middle nut in chamber spins freely, use fingers to turn, if not adjust setting to coarser, until it moves freely, then turn on grinder. All you have to do now is set your grind.

If it is under warranty, take it back. If not then it is a simple matter of replacing the switch. Take off the cover and pull out the switch. Mark each wire as you take it off. Take the switch with you to the store. First try a hardware store, then an auto parts store. If they don't have it try Sears. They will probably be able order it. Make sure you have the model number of your grinder. It is on a data plate somewhere on the grinder. If Sears can't get it, try a wholesale electrical parts house.

It should still be under warranty if it's that new, so why not just return it to Sears? They'll replace it for you, or at least take it in so their service department can fix it. There wouldn't be any charge to you.

I believe the thread is left hand, but close inspection should verify. Also you should never over tighten cutoff wheels or grinding wheels. You should be able to remove with a gloved hand while holding button on top with the other hand

Mike
Not sure what was happening when the previous reply was created, but the owners manual is part number 211260001 $7.99 at SearsPartsDirect.com

That said, I'm staring at my own copy of the the owners manual and I can't really see why you would want to pay for one. The only really useful information is the parts diagram which is online at SearsPartsDirect.com. The rest is generic grinder information (support workpiece, select proper wheel, etc.) and CYA (always wear gloves and eye protection, don't remopve safety guards, don't use damaged wheels, don't stick your finger in the light socket, don't cross the steet in the middle of the block, etc.)

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_