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Bring a meter when buying used motors

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matthewsx

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So, it turns out there are thieves that post broken stuff on Craigslist....

I drove all the way across the state to meet up with the seller of this motor. It looked good so I gave him $100 for this one and another that I now know has a bad bearing. Why does someone sell their broken stuff rather than just scrapping it?

Anyway, if you can't see it running assume scrap value I guess.

John

burned_motor.jpg
 

Cooter Brown

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Bearings are cheap and very easy to replace.... That coil on looks burnt on the bottom...
 

matthewsx

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The coil is definitely burnt, no continuity between any leg on this motor. It's a Baldor and looked really nice on the outside. The other motor is a Marathon and I will probably replace the bearing at some point to have as a backup. For now I have ordered new (surplus) from a reputable dealer.

I've done many deals through Craigslist and other places and have never had someone just straight-up rip me off. Most people are decent and will tell you if there's something wrong, this guy not so much....

John
 

Scra99tch

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I had someone drive up from Georgia (to NH) to look at a 30HP phase converter. I had it up and running through the summer but decided I need something way smaller, dimming lights in the house and a complaint from the wife helped me make the decision. Anyways The guy made it up here becuase I really dropped the price for him. It just happened to drop into the 20s that night and morning, from a comfortable 60+ fall day prior. I flip the switch and a squealing bearing noise made my heart drop.

He was visibly upset. I had dropped the price and actually refused another offer because he was already on his way up. I knocked off 35 bucks for another bearing he wanted another $150 off.

Lesson learned.... get a heated garage.
 

Z2V

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So, it turns out there are thieves that post broken stuff on Craigslist....

I drove all the way across the state to meet up with the seller of this motor. It looked good so I gave him $100 for this one and another that I now know has a bad bearing. Why does someone sell their broken stuff rather than just scrapping it?

Anyway, if you can't see it running assume scrap value I guess.

John
You didn’t notice a burnt smell coming from the motor?
 

RJSakowski

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I always take a meter with me when going to flea markets, hamfests, etc. I also take a pair of calipers and a micrometer.

I once bought a box of 100 watt incandescent bulbs after the seller looked me in the eye and told me there wasn't anything wrong with them. Technically, that was true....for a left hand thread light bulb. Buying something like a motor, I will plug it in before completing the deal. If I can't verify that it works, the seller will have to seriously reduce the price before I buy. Unless it's someone you know, never assume that what you hear is the truth.
 

hman

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It's also worthwhile to bring along either a stethoscope or a screwdriver, so you can listen to the bearings. A friend showed me how to use the screwdriver ... hold the blade against the bearing housing and the handle against your ear. Spin the shaft and listen for crunchies. The screwdriver conducts sound much better than air does.
 

Ulma Doctor

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one of the easiest tests is to simply spin the shaft.
any resistance or crunchy bearings would easily be noticed.

3 phase motors, in general, last for many years
generally speaking, bearings are a usual failure of electric motors.
i have motors in the field that have been running for 30 years or more, with only replacing the bearings.
field windings do go bad, but those failures are few and far between.
i work in a down right harsh environment, the motors are subjected to forces and idiots, possibly inconceivable in other industries.
i still marvel at how the motors survive for decades
 

john.k

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I dont care how good a motor is,unless its a TEFC with finned housing,it no more valuable than scrap.....many may not realize insurance policies require approved motors ,and no open ,or ventilated motor will be approved by UL......Often old woodworking machines have open motors ,and a good buildup of wood dust and paint overspray to stop the cooling of windings leads to shorts to the motor casing.Air compressor are also very prone to getting overspray inside the windings if not TEFC.
 
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