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  1. #1
    Join Date
    Mar 2013
    Location
    WI
    Posts
    112

    Default Save your bench grinder

    I was just using my bench grinder today,it reminded me of something I learned years back.
    I worked in an auto shop when I was younger. We had one of those wheel balancers that spins the tire and rim at a high speed,then tells you where to mount the wheel weights. We had a problem where we would burn out the motor on our balancer about every 6 months. One day the repair guy who came in told us to spin the wheel/tire by hand before we we hit the button to start it spinning. He said that motors draw their most current at O RPM,so if we gave it a little spin before we started the motor it would extend the life of our motor. Well,I worked at that shop another 3 years and no more burned out motors!
    I've applied this theory to my bench grinder since I bought it new years ago. It's just a el cheapo grinder that I bought about 20 years ago,BUT I bought one with big heavy grinding wheels,and quite a big motor. I've been in the habit of giving this heavy wheel a spin before I turn it on,and it still runs great to this day. Would it still run if I didn't spin it before I hit the go button? Who knows,but it's lasted me quite a long time for a cheap grinder.

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,694

    Default Re: Save your bench grinder

    Very good post.

  3. #3
    Join Date
    Jan 2008
    Posts
    2,194

    Default Re: Save your bench grinder

    The field coils in an electric motor see the same amount of current at all times that it is on, but the stator (rotor) coils see current only when the brush is in the position to energize them. This is why 'helping' it start extends the motor life since a stator that isn't moving is applying current for a much longer period than on one at full speed. The current becomes magnetism and heat and it's the heat that kills.

    Motors that die regularly are usually under-engineered or not adequately cooled. Use your compressor and blow nozzle to clear out the insides of your motors every time you use them and they will last longer. You'd be surprised how quickly motors can become clogged with dust in a shop environment!

    Phil

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