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Re: [SherlineCNC] Re: Disengaging motors from Gecko Driver....

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  • Marrocco, Sam
    ... Forgive me, Jo, I should have been more specific. What I should have said was that my goal is to be able to quickly, without having to physically unplug
    Message 1 of 8 , Apr 2, 2013
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      On Apr 2, 2013, at 8:16 PM, "jowhowho" <jowhowho@...> wrote:

      > "DO NOT DISCONNECT THE HIGH CURRENT CIRCUIT."
      >
      > If you have to turn the motors off, you should disconnect the power on the street voltage side of the transformer.
      >
      > The problem is that disconnecting or connecting a current running through an inductor can create lightening on a small scale.
      >
      > You can "get away with it", but you are asking for trouble.


      Forgive me, Jo, I should have been more specific.
      What I should have said was that my goal is to be able to quickly, without having to physically unplug the four motors from the gecko 540, disconnect them from the driver electrically once the power to the stepper driver had been deactivated. I have no intention of disconnecting them, physically or electrically while the power is on unless it could be done from within the gecko programmatically (and therefore, safely/in an approved fashion). Yes, pulling the plug in any method while power is applied would be bad.

      Sam Marrocco
      Chief Technical Officer
      248-548-2500 Main
      248-910-3344 Cell

      "Just because no one understands you doesn't make you an artist."

      RINGSIDE CREATIVE | INTEGRATED MEDIA STUDIO™
      http://www.ringsidecreative.com

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    • jowhowho
      Are you concerned about the effort it takes to turn a stepper attached to a de-energized driver, or are you concerned about damaging the driver? I think I saw
      Message 2 of 8 , Apr 2, 2013
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        Are you concerned about the effort it takes to turn a stepper attached to a de-energized driver, or are you concerned about damaging the driver?

        I think I saw Mariss Freimanis say it was okay to turn a motor that was attached to a turned off Gecko -- the induced currents are no worse for the circuits than what bounces back during normal driving. Of course you should confirm that -- it might have been someone else.


        I've often wished for little joysticks right on the machine tool for each motion -- pull the cross slide joystick, and the software commands the cross slide to move that direction. ...
      • Ron Ginger
        ... Pin 10 of the g540 is an enable signal. The drive will only work when it is grounded. To disable the motors simply add a switch to unground the pin and the
        Message 3 of 8 , Apr 3, 2013
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          > Are you concerned about the effort it takes to turn a stepper attached to a de-energized driver, or are you concerned about damaging the driver?
          >
          > I think I saw Mariss Freimanis say it was okay to turn a motor that was attached to a turned off Gecko -- the induced currents are no worse for the circuits than what bounces back during normal driving. Of course you should confirm that -- it might have been someone else.
          >
          >
          > I've often wished for little joysticks right on the machine tool for each motion -- pull the cross slide joystick, and the software commands the cross slide to move that direction. ...
          >

          Pin 10 of the g540 is an enable signal. The drive will only work when it
          is grounded. To disable the motors simply add a switch to unground the
          pin and the motors are electrically disconnected from the drive.

          It is OK to turn the motors without doing this, you will not hurt the
          motors, and unless you can crank very fast you will not feel a drag on
          the cranks.

          Mach supports many forms of joysticks, MPGs, and other hand controls to
          drive the motors. My favorite is the Shuttle which is a spring loaded
          handwheel that gives very smooth motion and nice 'feel' I often do
          roughing cuts to face off stock by just hand feeding with the shuttle.

          ron ginger
        • Sam Marrocco
          ... That sounds like exactly what I m looking for....looking closely, that is the E-Stop pin? So effectively, hit the E-Stop and the motors can be used
          Message 4 of 8 , Apr 3, 2013
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            On 4/3/2013 7:23 AM, Ron Ginger wrote:
            >
            >
            >
            > Pin 10 of the g540 is an enable signal. The drive will only work when it
            > is grounded. To disable the motors simply add a switch to unground the
            > pin and the motors are electrically disconnected from the drive.
            >


            That sounds like exactly what I'm looking for....looking closely, that
            is the E-Stop pin? So effectively, hit the E-Stop and the motors can be
            used manually with no electrical "repercussions" to the motors or the
            G540. Even better, the power is left on during operations. Then it is up
            to me to remember that I've moved motors and that they will need to be
            re-homed. Adding some homing/limit switches is next on my todo list.


            >
            > It is OK to turn the motors without doing this, you will not hurt the
            > motors, and unless you can crank very fast you will not feel a drag on
            > the cranks.
            >

            I assume you mean this "while the G540 power is off" since it is not
            possible to move the motors with the power on without doing this.

            >
            > Mach supports many forms of joysticks, MPGs, and other hand controls to
            > drive the motors. My favorite is the Shuttle which is a spring loaded
            > handwheel that gives very smooth motion and nice 'feel' I often do
            > roughing cuts to face off stock by just hand feeding with the shuttle.
            >



            I have a Griffin knob that I was using for a Quicktime player that I
            wrote.....it is pretty useful and I will try it on the Mill. The only
            detriment I see with an external pot like that is the lake of tactile
            feeback.


            Sam Marrocco
            Chief Technical Officer
            248-548-2500 Main
            248-910-3344 Cell

            "Just because no one understands you doesn't make you an artist."

            RINGSIDE CREATIVE | INTEGRATED MEDIA STUDIO™
            http://www.ringsidecreative.com

            Find us on Facebook.

            Please consider the environment before printing this email.



            [Non-text portions of this message have been removed]
          • intenselymellow
            It is possible to crank steppers with the driver s powered and activated, it s just not easy. It s MUCH easier to crank em with the power of. But cranking
            Message 5 of 8 , Apr 4, 2013
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              It is possible to crank steppers with the driver's powered and
              activated, it's just not easy. It's MUCH easier to crank 'em with the
              power of. But cranking them generates back EMF. Not enough to harm
              the drivers, but easily enough to feed them enough power to "fight"
              you. So disabling is vastly superior to simply powering off.

              That said, this "E-stop" thing should work but is a bit less than
              ideal. In theory E-stop is for emergencies and isn't really for
              day to day configuration. Genuine "E-stop" is supposed to do a lot
              more than just disalbe the drivers. That aside, it's much better
              to have individual axis control rather than global axis control.
              As has been noted elsewhere you can lose up to two steps in position
              disabling an axis and re-enabling it (though generally only if you
              move it). And they make handy locks if you only want to move one
              axis, etc.

              I have only ever wired up G203's single axix drivers and Xylotex 3
              and 4 axis drivers, which break out each enable seperately. In each
              case it was simple to enable/disable each axis. I can see that each
              G250 on the G540 has an individual enable. But it seems that these
              have all been tied together on the G540 backplane.

              If you wanted to wire each axis seperately you could break the
              connection on the G540 and control each G250 seperately. Using
              a few diodes it's not to hard to create sepperate and global
              controls.

              If you don't want to tear into the G540... You should be able to
              simply short the current set resistor. Since an open there equals
              max current 0 ohms SHOULD equal 0 current and disabled. Though, by
              all means, check with Mariss at Gecko first. Assuming this works
              individual enables would be pretty easy to wire up. I'm not sure
              how you'd do a global disable though, unless you use the "E-stop."

              Good luck

              Jeff



              On Wed, April 3, 2013 8:34 am, Sam Marrocco wrote:
              >
              > On 4/3/2013 7:23 AM, Ron Ginger wrote:
              >>
              >>
              >>
              >> Pin 10 of the g540 is an enable signal. The drive will only work when it
              >> is grounded. To disable the motors simply add a switch to unground the
              >> pin and the motors are electrically disconnected from the drive.
              >>
              >
              >
              > That sounds like exactly what I'm looking for....looking closely, that
              > is the E-Stop pin? So effectively, hit the E-Stop and the motors can be
              > used manually with no electrical "repercussions" to the motors or the
              > G540. Even better, the power is left on during operations. Then it is up
              > to me to remember that I've moved motors and that they will need to be
              > re-homed. Adding some homing/limit switches is next on my todo list.
              >
              >
              >>
              >> It is OK to turn the motors without doing this, you will not hurt the
              >> motors, and unless you can crank very fast you will not feel a drag on
              >> the cranks.
              >>
              >
              > I assume you mean this "while the G540 power is off" since it is not
              > possible to move the motors with the power on without doing this.
            • cnc sales
              I havent tried a G540, but i routinely enable /disable the x on my lathe, with a G203V, or the Z, with a servo G320. ... -- -hanermo [Non-text portions of this
              Message 6 of 8 , Apr 4, 2013
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                I havent tried a G540, but i routinely enable /disable the x on my
                lathe, with a G203V, or the Z, with a servo G320.


                >


                --
                -hanermo



                [Non-text portions of this message have been removed]
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