Loading ...
Sorry, an error occurred while loading the content.

advice - fried z axis stepper driver

Expand Messages
  • Tom Trikalinos
    Hi, newbie here. Bought a used CNC 5400 mill and was configuring it today. The whole CNC mod was factory installed, I was told at least. I was running the
    Message 1 of 6 , Jul 1 10:08 PM
    • 0 Attachment
      Hi, newbie here.
      Bought a used CNC 5400 mill and was configuring it today. The whole
      CNC mod was factory installed, I was told at least.

      I was running the configuration wizard of EMC2, and I fried the
      stepper driver for the Z axis doing a test-the-z-axis jog... The motor
      was trying to lift the headstock, could not, and I kept going at it
      till the whiff of smoke emerged from the control box... (btw I did
      not use the springs to help it lift the headstock) . Oh well.

      The motor is OK -- the driver is dead. (verified driver IC death with
      oscilloscope.) For now, I have reconfigured to use the A axis stepper
      driver for the Z-axis and ordered a new driver IC to replace the fried
      one... But I will not play any longer before making sure this does not
      happen again..

      I guess I'm asking, did anyone have this problem?
      Might I need to make sure that the leadscrew turns more freely?
      Hand cranking Z axis, seems a bit tight. (I got a manual lathe that
      cranks nicely with .003" backlash...)

      PS1. I'm using an HP laptop for EMC2 -- latency test passes... running
      an other one overnight...
      PS2. I saw a nice counterbalance (http://www.philmattison.com/) will
      try to copy/adapt.

      best

      tom
    • Ron Ginger
      ... You should not be able to fry a stepper driver by stalling it- steppers are always stalled when they are not moving. Either the driver voltage is to high,
      Message 2 of 6 , Jul 2 2:20 PM
      • 0 Attachment
        > Hi, newbie here.
        > Bought a used CNC 5400 mill and was configuring it today. The whole
        > CNC mod was factory installed, I was told at least.
        >
        > I was running the configuration wizard of EMC2, and I fried the
        > stepper driver for the Z axis doing a test-the-z-axis jog... The motor
        > was trying to lift the headstock, could not, and I kept going at it
        > till the whiff of smoke emerged from the control box... (btw I did
        > not use the springs to help it lift the headstock) . Oh well.
        >
        > The motor is OK -- the driver is dead. (verified driver IC death with
        > oscilloscope.) For now, I have reconfigured to use the A axis stepper
        > driver for the Z-axis and ordered a new driver IC to replace the fried
        > one... But I will not play any longer before making sure this does not
        > happen again..
        >
        > I guess I'm asking, did anyone have this problem?
        > Might I need to make sure that the leadscrew turns more freely?
        > Hand cranking Z axis, seems a bit tight. (I got a manual lathe that
        > cranks nicely with .003" backlash...)
        >
        >

        You should not be able to fry a stepper driver by stalling it- steppers
        are always stalled when they are not moving. Either the driver voltage
        is to high, or the current limit resistors are wrong allowing the driver
        to pass to much current. If you simply change the chip you will likely
        fry the new one.

        ron ginger
      • Tom Trikalinos
        Ron, you are right that there is a different problem. The box is the original by sherline, and the current limiting resistors of the Z axis are the same as in
        Message 3 of 6 , Jul 2 8:48 PM
        • 0 Attachment
          Ron,
          you are right that there is a different problem. The box is the
          original by sherline, and the current limiting resistors of the Z axis
          are the same as in the other axes.

          I think I found (a) problem... The connection of the cable to the
          stepper motor of the Z axis is via male/female headers. The cable's
          female header is defective (abused) and only one of the 4 half-coils
          closes circuit. The other 3 are open.

          Unclear if this is the problem -- not obvious to me why this would fry
          half the stepper motor driver IC.

          I opened the motor and soldered the wires directly. No macroscopic
          damage on motor wiring.

          Tomorrow I will whip up a new controller and will post my progress or demise.


          Thanks for the feedback.

          tom






          On Thu, Jul 2, 2009 at 5:20 PM, Ron Ginger<ronginger@...> wrote:
          >
          >
          >
          >> Hi, newbie here.
          >> Bought a used CNC 5400 mill and was configuring it today. The whole
          >> CNC mod was factory installed, I was told at least.
          >>
          >> I was running the configuration wizard of EMC2, and I fried the
          >> stepper driver for the Z axis doing a test-the-z-axis jog... The motor
          >> was trying to lift the headstock, could not, and I kept going at it
          >> till the whiff of smoke emerged from the control box... (btw I did
          >> not use the springs to help it lift the headstock) . Oh well.
          >>
          >> The motor is OK -- the driver is dead. (verified driver IC death with
          >> oscilloscope.) For now, I have reconfigured to use the A axis stepper
          >> driver for the Z-axis and ordered a new driver IC to replace the fried
          >> one... But I will not play any longer before making sure this does not
          >> happen again..
          >>
          >> I guess I'm asking, did anyone have this problem?
          >> Might I need to make sure that the leadscrew turns more freely?
          >> Hand cranking Z axis, seems a bit tight. (I got a manual lathe that
          >> cranks nicely with .003" backlash...)
          >>
          >>
          >
          > You should not be able to fry a stepper driver by stalling it- steppers
          > are always stalled when they are not moving. Either the driver voltage
          > is to high, or the current limit resistors are wrong allowing the driver
          > to pass to much current. If you simply change the chip you will likely
          > fry the new one.
          >
          > ron ginger
          >
          >
        • montanaaardvark
          ... Tom, One of the dire warnings that other driver manufacturers give is that if you open any of the wires to the motor while powered on you _will_ blow the
          Message 4 of 6 , Jul 3 7:38 AM
          • 0 Attachment
            --- In SherlineCNC@yahoogroups.com, Tom Trikalinos <ttrikalin@...> wrote:
            >
            > Ron,
            > you are right that there is a different problem. The box is the
            > original by sherline, and the current limiting resistors of the Z axis
            > are the same as in the other axes.
            >
            > I think I found (a) problem... The connection of the cable to the
            > stepper motor of the Z axis is via male/female headers. The cable's
            > female header is defective (abused) and only one of the 4 half-coils
            > closes circuit. The other 3 are open.
            >
            > Unclear if this is the problem -- not obvious to me why this would fry
            > half the stepper motor driver IC.
            >
            > I opened the motor and soldered the wires directly. No macroscopic
            > damage on motor wiring.
            >
            > Tomorrow I will whip up a new controller and will post my progress or demise.
            >
            >
            > Thanks for the feedback.
            >
            > tom
            >
            >
            >
            >
            Tom,


            One of the dire warnings that other driver manufacturers give is that if you open any of the wires to the motor while powered on you _will_ blow the driver chip. I think it has to do with badly un-balancing the output circuit. Likewise, I think it's worse with small integrated drivers like the Allegro chips. Maybe if you have large power transistors they'll be more rugged.

            Make sure those wires are connected solidly, or you will blow the new one.


            Bob
            Montana_Aardvark
          • Tom Trikalinos
            Bob, you are correct: The problem _was_ the motor connections. I will post photos with details of the fix... Briefly, there were 2 tiny fractures in each of 2
            Message 5 of 6 , Jul 3 10:54 AM
            • 0 Attachment
              Bob, you are correct:

              The problem _was_ the motor connections. I will post photos with
              details of the fix...

              Briefly, there were 2 tiny fractures in each of 2 out of six copper
              traces on the small pcb inside the NEMA 23 motor. They are stress
              fractures (pardon the terminology, occupational perversion) located
              exactly where the copper trace met the pad, at the soldering junction
              for the male headers... The fractures were practically invisible
              before desoldering the old connection. Restored the connections, the
              motor runs beautifully.

              Waiting for the allegro IC to fix the Z axis of the box. For good or
              ill I put heat sinks... oh well.

              thanks once more for the feedback,

              t




              On Fri, Jul 3, 2009 at 10:38 AM, montanaaardvark<boblombardi@...> wrote:
              >
              >
              > --- In SherlineCNC@yahoogroups.com, Tom Trikalinos <ttrikalin@...> wrote:
              >>
              >> Ron,
              >> you are right that there is a different problem. The box is the
              >> original by sherline, and the current limiting resistors of the Z axis
              >> are the same as in the other axes.
              >>
              >> I think I found (a) problem... The connection of the cable to the
              >> stepper motor of the Z axis is via male/female headers. The cable's
              >> female header is defective (abused) and only one of the 4 half-coils
              >> closes circuit. The other 3 are open.
              >>
              >> Unclear if this is the problem -- not obvious to me why this would fry
              >> half the stepper motor driver IC.
              >>
              >> I opened the motor and soldered the wires directly. No macroscopic
              >> damage on motor wiring.
              >>
              >> Tomorrow I will whip up a new controller and will post my progress or
              >> demise.
              >>
              >>
              >> Thanks for the feedback.
              >>
              >> tom
              >>
              >>
              >>
              >>
              > Tom,
              >
              > One of the dire warnings that other driver manufacturers give is that if you
              > open any of the wires to the motor while powered on you _will_ blow the
              > driver chip. I think it has to do with badly un-balancing the output
              > circuit. Likewise, I think it's worse with small integrated drivers like the
              > Allegro chips. Maybe if you have large power transistors they'll be more
              > rugged.
              >
              > Make sure those wires are connected solidly, or you will blow the new one.
              >
              > Bob
              > Montana_Aardvark
              >
              >
            • Tom Trikalinos
              I added 7 photos on the repair of the Z-axis motor and of the fried Z-axis controller of my mill... album tat - stepper motor repair The Minebea steppers
              Message 6 of 6 , Sep 5, 2009
              • 0 Attachment
                I added 7 photos on the repair of the Z-axis motor and of the fried
                Z-axis controller of my mill...
                album "tat - stepper motor repair"

                The Minebea steppers that sherline chose have a plug to connect the
                cable. The movement of the cable up and down strained the pcb in the
                motor causing a hairline fracture of a track of the PCB,
                intermittently breaking circuit.

                This was more than enough to fry my Z-axis controller...

                May be useful for someone else...

                best

                tom trikalinos




                On Fri, Jul 3, 2009 at 1:54 PM, Tom Trikalinos<ttrikalin@...> wrote:
                > Bob, you are correct:
                >
                > The problem _was_ the motor connections. I will post photos with
                > details of the fix...
                >
                > Briefly, there were 2 tiny fractures in each of 2 out of six copper
                > traces on the small pcb inside the NEMA 23 motor. They are stress
                > fractures (pardon the terminology, occupational perversion) located
                > exactly where the copper trace met the pad, at the soldering junction
                > for the male headers... The fractures were practically invisible
                > before desoldering the old connection.  Restored the connections, the
                > motor runs beautifully.
                >
                > Waiting for the allegro IC to fix the Z axis of the box. For good or
                > ill I put heat sinks... oh well.
                >
                > thanks once more for the feedback,
                >
                > t
                >
                >
                >
                >
                > On Fri, Jul 3, 2009 at 10:38 AM, montanaaardvark<boblombardi@...> wrote:
                >>
                >>
                >> --- In SherlineCNC@yahoogroups.com, Tom Trikalinos <ttrikalin@...> wrote:
                >>>
                >>> Ron,
                >>> you are right that there is a different problem. The box is the
                >>> original by sherline, and the current limiting resistors of the Z axis
                >>> are the same as in the other axes.
                >>>
                >>> I think I found (a) problem... The connection of the cable to the
                >>> stepper motor of the Z axis is via male/female headers. The cable's
                >>> female header is defective (abused) and only one of the 4 half-coils
                >>> closes circuit. The other 3 are open.
                >>>
                >>> Unclear if this is the problem -- not obvious to me why this would fry
                >>> half the stepper motor driver IC.
                >>>
                >>> I opened the motor and soldered the wires directly. No macroscopic
                >>> damage on motor wiring.
                >>>
                >>> Tomorrow I will whip up a new controller and will post my progress or
                >>> demise.
                >>>
                >>>
                >>> Thanks for the feedback.
                >>>
                >>> tom
                >>>
                >>>
                >>>
                >>>
                >> Tom,
                >>
                >> One of the dire warnings that other driver manufacturers give is that if you
                >> open any of the wires to the motor while powered on you _will_ blow the
                >> driver chip. I think it has to do with badly un-balancing the output
                >> circuit. Likewise, I think it's worse with small integrated drivers like the
                >> Allegro chips. Maybe if you have large power transistors they'll be more
                >> rugged.
                >>
                >> Make sure those wires are connected solidly, or you will blow the new one.
                >>
                >> Bob
                >> Montana_Aardvark
                >>
                >>
                >
              Your message has been successfully submitted and would be delivered to recipients shortly.