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Electric Power & Utilities/Question (previously answered) about Sears grinder.


QUESTION: Charlie, I recently saw your answer about correct wiring for a Sears 6" grinder from another guy who did the same thing I did (removed the lights and couldn't rewire correctly). I followed your instructions, the motor turned and the wheels turned. I wrote to thank (thrice bless, actually) you, but I spoke a bit too soon. (I still thank you whatever the outcome...) I put a felt polishing wheel on the grinder, and turned it on. The wheels turned, although even after they ramped up they seemed to be going less fast than the proper 3650rpm. Now the problem: as soon as I pressed a chisel blade against the wheel to polish the bevel, the motor slowed down (even with relatively light pressure; firmer pressure stopped the wheel completely). I undid then redid the wiring as you instructed...same thing happens. What should I do now? Thank you. John

ANSWER: Have you checked the capacitors? is the wheel larger than 6 inches? Does it start quickly? knowing these answers would help me diagnose better.

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QUESTION: Charlie, Yes, I checked the capacitor. It's a 10mF and the meter read 10.3, so I think the capacitor is OK. The wheels are 6"; when I turn the switch on they start to turn immediately, they "ramp up" in 3-4 seconds, but seem to be running at about half the normal 3650rpm. (I also have a slow speed grinder, so I'm estimating speed by sound.) In any case, the 6" Sears has no "power", and bogs down with the slightest pressure/stops with any working pressure at all. Thanks for any thoughts you might have. (Could having removed the working lights have anything to do with the loss of speed and power?)  Best regards, John

ANSWER: The lights should not cause the problem. My guess is that it is running only the start winding, and the main windings are not energized. I have no information on craftsman products, so i am not able to give any diagrams or such.

---------- FOLLOW-UP ----------

QUESTION: Charlie, Final question: how do I "energize" the main windings? Thank you. John

From this point on it requires complete dis-assemble of the motor. You could take it to a service center, as they might "see" something I cant. At my shop, there is a minimum charge of $30.00 to dis-assemble a motor. motors this small are usually not worth the expense.  

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Charles C. Jones


Let Me help you with your problems with single phase and three phase electric motors. I can tell you how to troubleshoot your motor problems. From simple testing of capacitors, how to test your windings, replacing bearings, and general maintenance. Before we go any further, remember these words of advice: Disconnect the power before you do anything! Please limit your questions to electric motors and there immediate components. I review each question, and if I can answer or help, then I will. If you receive a rejection, it means it is out of my expertise, and just do not have the answer. I'll be waiting for your question.


I have 40 years experience in the repair of electric motors and related equipment. I am a master machinist in the field of motor repair. I was employed with my company for 35 years, but retired in May of 2013. The downside to that is I lost access to a lot of technical data. I will still try to give you the most accurate advice that I can.

Former member EASA

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