Dead mill

Discussion in 'General Engine Discussion' started by Sshire, Dec 25, 2011.

  1. Dec 25, 2011 #1

    Sshire

    Sshire

    Sshire

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    So there I was. Milling another part for Elmer's Grasshopper and the BF20 mill started, stopped, started, stopped. :-\
    That's it. Stopped. Fuse fine. Unplugged and replugged every connector in the control box. Used my patented, "smack the part with my hand" technique. Nothing. The RPM indicator is lit and shows 0 RPM. Motor not turning.
    I'll call PrecisionMatthews in the morning. Unless someone has an idea, I'll start on part I can make on the lathe.
    At least I can look at my new Bison 5C Set Tru chuck until its faceplate arrives ;D
    Bummer

    Stan
     
  2. Dec 25, 2011 #2

    Jasonb

    Jasonb

    Jasonb

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    Have a look at teh brushes

    J
     
  3. Dec 25, 2011 #3

    Tin Falcon

    Tin Falcon

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    I would start troubleshooting with a multimeter see where the power is not getting through could be the motor could be the power supply/ Pusle width modulator. sounds like you ruled out a loose connection could be something as simple as a broken wire or bad connector. IIRC that is under warranty so would not go any further than part level troubleshooting. Sometimes something simple.
    Tin
     
  4. Dec 26, 2011 #4

    Sshire

    Sshire

    Sshire

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    IT'S ALIVE!!!
    Jasonb gets the prize. Thank you, thank you.
    I pulled the motor cover and was going take Tin's suggestion to get out the multimeter and start checking voltages, etc. when I remembered Jason's post. Took out brush #1. Slipped out very smoothly and was clean and shiny. Brush #2 was stuck. VERY gentle pulling and wiggling followed. Finally popped loose. The brush was very dull looking. 600 grit around a 0.25 dowel and got it clean and shiny. Replaced brush. Fingers crossed. IT WORKED!!! Christmas miracle.
    Thanks for all the suggestions. Having a very limited knowledge of motors, can someone explain what caused one brush to get stuck and dull looking? Is it something I did?
    Anyway, we now return you to your regularly scheduled milling.
    Best
    Stan
     
  5. Dec 27, 2011 #5

    Jasonb

    Jasonb

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    Can't tell you why apart maybe from poor fit to start with. Had a similar problem with my lathe where one brush had worn more than teh other, got hot and softened the spring.

    [​IMG]
     
  6. Dec 27, 2011 #6

    Springbok

    Springbok

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    Looking at the r/h brush I think it would be worthwhile ordering a new set

    Bob
     
  7. Dec 27, 2011 #7

    Jasonb

    Jasonb

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    I did better than that, ordered a new set and another as a spare :) you know that if they fail again it will be just at the wrong time.

    J
     
  8. Dec 27, 2011 #8

    Ken I

    Ken I

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    Almost certainly nothing that you did - sometimes a small fragment chips off and wedges the brush - other times its simply build up of dust - they can also get stuck fom overheating - particularly if they were a tight fit in the first place.

    Always a good idea to pull them out once a year and give the motor a blow out with compressed air - put the brushes back the exact same way they came out.

    Inspect the trailing edges of the brushes and the com for signs of arcing, brush bounce etc - if the com looks a mess - it might be in need of a skim.

    Ken
     
  9. Dec 27, 2011 #9

    n4zou

    n4zou

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    I had that same problem with the starter motor on my scoot. I opened up the starter and found the brush slot had never been deburred. The brush had hung up in the slot. A new starter would have cost over $100. I cleaned up the slot with some jewellers files, reassembled the starter, and put it back on the scoot. It spun the engine over faster than it ever had before.
     

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