Starting switch above motor in mill

My experience is similar. I have a ton of motors, several older then me, and many Chinese born. I have replaced several start capacitors, but never had any welded switches, but do have one that the plastic holding the switch gave up.

Hopefully, someone much smarter then I can answer if the welded contacts are more of a fluke, or could it be a sign of a dying capacitor sucking more then normal current. If not, I would run the mill, and write it up as a learning experience, that is likely never to happen again.
 
Same here, when the start cap blew on my mill I called Matt (not knowing what the problem was), he suggested that I check the caps & the centrifugal switch. Or he offered to just send me a new motor. It wasn't welded together but I cleaned the contacts anyway only cause I had the motor apart. Ended up only being the start cap which Matt also offered to send me. I just bought a new start & run cap (although the run cap was still good) from Grainger the next morning. That was 5 yrs ago & never had a problem since with any of the motors in my home shop.
 
Firstgear: contacts like those should last for years with intermittent use. Good to have a spare around too especially if you can still buy them new.
Mark
 
There often seems to be no rhyme or reason why, or when, centrifugal switches fail. I live in the land of the lawn irrigation system, all most every house has one. In general they run a couple of hours a day 3 to 4 days a week, 52 weeks a year. About 80% of them have the exact same Flotec pump. I've seen the switches fail in 2 months and others last 20 years. On multiple occasions I've pried apart welded contacts, sanded them smooth and they never stuck again. Cause remained a mystery.
 
I have about 20 motors in my shop, and my Dad had 10. We've never had a single set of contacts burn out, in a cumulative 70 years. If they work for the first 100 starts, they should work for a very long time, almost a lifetime. Failure is usually due to a defect in manufacture.
 
Contact welding is caused by arcing. Part of t he capacitor's job is to prevent arcing when the contacts break. It may be defective or have a cold solder joint.
 
Had a problem with a new Chinese motor I installed on a lathe. The contacts kept sticking all the time. Upgraded to a larger hp motor and the problem was solved.
Barry


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