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Thread: Putting the shop together

  1. #31
    10 years old isn't so bad. Sometimes a contactor will weld shut when the coil is on its way out and chattering. Just out of curiosity, what do you measure in ohms across A1-A2?

    http://www.nhdi.com.tw/eng_Con_thr_c-ser.html

  2. #32
    Quote Originally Posted by negativ3 View Post
    10 years old isn't so bad. Sometimes a contactor will weld shut when the coil is on its way out and chattering. Just out of curiosity, what do you measure in ohms across A1-A2?
    Okay, I fess up, I pushed the REV button when the mill was turning in the FWD direction without hitting the STOP button first. I just finished analyzing the control circuit and found a poor design. I cancelled my order for contactors because I'm going to get some with a NC/NO set of contacts. The designed circuit would work with snap switches but doesn't work with the momentary push buttons but, snap switches are not desirable in this application.

  3. #33
    This is one way to correct for a poor circuit design
    It says "Warning change spindle direction only when motor is stopped"
    IMG_1102.JPG
    I recall reading a clarification in a manual or something saying extensive damage to the machine may result from disregarding these instructions.

    This is the schematic diagram of the control circuit for the milling machine.
    IMG_1101.JPG
    Last edited by AlPuddle; 11-11-2017 at 03:54 PM. Reason: clarification

  4. #34
    :lol:

    A $200 VFD may be your friend off fleabay. Much kinder with soft start capabilities.

  5. #35
    I was wondering what the going price was for a VFD. Thinking about attaching one to a belt sander.
    But the mill won't get one. Nope. It doesn't deserve one. It's got negative karma.

  6. #36
    Senior Member chubbyjp77's Avatar
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    Put a two pole double throw switch in your control circuit that has the latch power supply ran through a pole. Any time you change direction the motor starter that’s engaged will turn off. The other pole dictates which starter draws in Simple and reliable.

  7. #37
    Quote Originally Posted by AlPuddle View Post
    I was wondering what the going price was for a VFD. Thinking about attaching one to a belt sander.
    But the mill won't get one. Nope. It doesn't deserve one. It's got negative karma.
    Sounds like the mill is evil and must be punished

  8. #38
    Senior Member chubbyjp77's Avatar
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    AlPuddle, sent you a PM.

  9. #39
    Finally, the mill is running again. I replaced the contactors and added a mechanical interlock so I can't engage both contactors at the same time. AutomationDirect had reasonably priced contactors and thermal overloads as well as new switches. After assembling the control box, the motor didn't run, just hummed. Had the motor checked out at the motor shop and it was okay. While it was there, I had them change the bearings and internal switch. Turned out I wired it up wrong but I got that worked out. So, life is good.

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