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  • Re: MIG wire speed control problems

    From Thesykboy@21:1/5 to All on Sat May 13 21:15:03 2023
    Hey gang, I read this thread in hopes of finding the cure to my issue (which is similar). Got a Craftsman (Century) from 1992. First time in years I’ve used it and I’ve noticed the wire feed is slow AND weak. I can literally stop the wire feed
    roller with my fingers (and reasonable pressure) on full speed. I’ve replace the gun, liner, and everything recently because the old one was just too stiff. I also did so in hopes it would solve the feed issue… nope.

    I’ve tested the motor on a 12v battery directly and can see that it and the gearbox are working fine - torque and speed. It was hauling ass and I couldn’t stop it with the same pressure as before. I spoke to someone at Lincoln (who now owns Century)
    and was told the board is likely not putting out the amps the motor needs for proper torque. I just bought the board, but don’t want to throw parts at it. I know something isn’t putting out the right amount of juice and I’m trying to figure out
    where it’s NOT coming from. Does this make sense to anyone else? I know things get old and stop working, but like the others, I’m not familiar with circuitry and and reluctant to just throw parts at it. I love this welder and really want it to work.

    Thanks in advance for the knowledge.

    -Jason from Denver.

    --
    For full context, visit https://www.polytechforum.com/welding/mig-wire-speed-control-problems-9075-.htm

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  • From Jim Wilkins@21:1/5 to All on Sat May 13 18:09:00 2023
    "Thesykboy" wrote in message news:175ed073079f0ac8$36$565070$[email protected]...

    Hey gang, I read this thread in hopes of finding the cure to my issue
    (which is similar). Got a Craftsman (Century) from 1992. First time in years I’ve used it and I’ve noticed the wire feed is slow AND weak. I can
    literally stop the wire feed roller with my fingers (and reasonable
    pressure) on full speed. I’ve replace the gun, liner, and everything recently because the old one was just too stiff. I also did so in hopes it would solve the feed issue… nope.

    I’ve tested the motor on a 12v battery directly and can see that it and the gearbox are working fine - torque and speed. It was hauling ass and I couldn’t stop it with the same pressure as before. I spoke to someone at Lincoln (who now owns Century) and was told the board is likely not putting
    out the amps the motor needs for proper torque. I just bought the board, but don’t want to throw parts at it. I know something isn’t putting out the
    right amount of juice and I’m trying to figure out where it’s NOT coming
    from. Does this make sense to anyone else? I know things get old and stop working, but like the others, I’m not familiar with circuitry and and reluctant to just throw parts at it. I love this welder and really want it
    to work.

    Thanks in advance for the knowledge.

    -Jason from Denver.

    ---------------------

    Posted to sci.engr.joining.welding

    The schematic for a Century Powermate 70 shows two apparently selenium rectifiers, a speed control pot and the torch switch in the wire feed motor drive. Any of them could be the problem.
    -jsw

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  • From Richard Smith@21:1/5 to Jim Wilkins on Sun May 14 20:54:30 2023
    "Jim Wilkins" <[email protected]> writes:

    "Thesykboy" wrote in message news:175ed073079f0ac8$36$565070$[email protected]...

    Hey gang, I read this thread in hopes of finding the cure to my issue
    (which is similar). Got a Craftsman (Century) from 1992. First time in
    years I’ve used it and I’ve noticed the wire feed is slow AND weak. I can literally stop the wire feed roller with my fingers (and reasonable pressure) on full speed. I’ve replace the gun, liner, and everything recently because the old one was just too stiff. I also did
    so in hopes it would solve the feed issue… nope.

    I’ve tested the motor on a 12v battery directly and can see that it and the gearbox are working fine - torque and speed. It was hauling
    ass and I couldn’t stop it with the same pressure as before. I spoke to someone at Lincoln (who now owns Century) and was told the board is
    likely not putting out the amps the motor needs for proper torque. I
    just bought the board, but don’t want to throw parts at it. I know something isn’t putting out the right amount of juice and I’m trying to figure out where it’s NOT coming from. Does this make
    sense to anyone else? I know things get old and stop working, but like
    the others, I’m not familiar with circuitry and and reluctant to
    just throw parts at it. I love this welder and really want it to work.

    Thanks in advance for the knowledge.

    -Jason from Denver.

    ---------------------

    Posted to sci.engr.joining.welding

    The schematic for a Century Powermate 70 shows two apparently selenium rectifiers, a speed control pot and the torch switch in the wire feed
    motor drive. Any of them could be the problem.
    -jsw

    A wider overall point:

    With a MIG / GMAW welder, you deliberately set the drive rolls so they
    will skid if the wire jams.
    You set the pressure so the wire will feed, but any more resistance
    than regular feed and the rolls slip on the wire.
    That's the reason for the springs on the toggles mechanism for the
    drive rolls.

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  • From Thesykboy@21:1/5 to All on Sun May 14 23:02:24 2023
    The problem is, there doesn’t seem to be enough amps to the feed motor to power it with the torque it needs to move the wire. I’ve run the wire through 2 different liners and the resistance in the feed is the same. So I’m guessing the motor has to
    have a bit of torque to feed the wire.

    Last night I tested amps where the leads come from the board to the motor. When the pot is set at 2, it reads .26 amps. When I keep cranking it up to 6, it hits .30 amps, and at 8…. same .30 amps. I’ve looked at other motors online to get a baseline
    of how many amps that motor should need to do its job. Even the cheap ones on Amazon are doing .90, so I’m thinking the amps coming from the board are way too low. I found a company that sells a new OE board with pot and voltage dials on it for a
    decent price. I don’t want to just throw parts at it, but in my research so far, everything points to what is sending amps the the motor… the board.

    Sound about right?

    --
    For full context, visit https://www.polytechforum.com/welding/mig-wire-speed-control-problems-9075-.htm

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jim Wilkins@21:1/5 to All on Sun May 14 19:27:24 2023
    "Thesykboy" wrote in message news:175f24e35dcf3418$1$3685597$[email protected]...

    The problem is, there doesn’t seem to be enough amps to the feed motor to
    power it with the torque it needs to move the wire. I’ve run the wire through 2 different liners and the resistance in the feed is the same. So I’m guessing the motor has to have a bit of torque to feed the wire.

    Last night I tested amps where the leads come from the board to the motor.
    When the pot is set at 2, it reads .26 amps. When I keep cranking it up to
    6, it hits .30 amps, and at 8…. same .30 amps. I’ve looked at other
    motors online to get a baseline of how many amps that motor should need to
    do its job. Even the cheap ones on Amazon are doing .90, so I’m thinking the amps coming from the board are way too low. I found a company that sells
    a new OE board with pot and voltage dials on it for a decent price. I don’t want to just throw parts at it, but in my research so far, everything points to what is sending amps the the motor… the board.

    Sound about right?

    ------------------------------

    A partly open bridge rectifier diode will give you the no-load voltage but
    not the full current. Half-wave rectification is obvious if you have an oscilloscope. It might show up as a large voltage difference between when
    the motor is connected and disconnected.

    If you can find an electrical schematic for it I might be able to suggest
    other tests to locate the fault.

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    * Origin: fsxNet Usenet Gateway (21:1/5)