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The Use of Quadrature Encoders on the XYZ axis

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  • sjblair4
    Has anyone added quadrature encoders to each axis stepper motor to use them as a missed step detector, and made the system closed-loop like MaxCNC?
    Message 1 of 19 , Sep 1, 2008
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      Has anyone added quadrature encoders to each axis stepper motor to use
      them as a missed step detector, and made the system closed-loop like
      MaxCNC?
    • Paul Castellese
                         I have servo motors set up that way, but you need servo drivers to run them. ... From: sjblair4
      Message 2 of 19 , Sep 2, 2008
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                           I have servo motors set up that way, but you need servo drivers to run them.

        --- On Mon, 9/1/08, sjblair4 <sjblair4@...> wrote:

        From: sjblair4 <sjblair4@...>
        Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ axis
        To: turbocnc@yahoogroups.com
        Date: Monday, September 1, 2008, 9:33 PM






        Has anyone added quadrature encoders to each axis stepper motor to use
        them as a missed step detector, and made the system closed-loop like
        MaxCNC?


















        [Non-text portions of this message have been removed]
      • sjblair4
        ... need servo drivers to run them. ... use ... like
        Message 3 of 19 , Sep 2, 2008
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          --- In turbocnc@yahoogroups.com, Paul Castellese <pcastellese@...>
          wrote:
          >
          >                    I have servo motors set up that way, but you
          need servo drivers to run them.
          >
          > --- On Mon, 9/1/08, sjblair4 <sjblair4@...> wrote:
          >
          > From: sjblair4 <sjblair4@...>
          > Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ axis
          > To: turbocnc@yahoogroups.com
          > Date: Monday, September 1, 2008, 9:33 PM
          >
          >
          >
          >
          >
          >
          > Has anyone added quadrature encoders to each axis stepper motor to
          use
          > them as a missed step detector, and made the system closed-loop
          like
          > MaxCNC?
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          > [Non-text portions of this message have been removed]
          >
        • sjblair4
          This is just because the servo driver has quad encoder inputs and stepper motor drivers do not. I m a retired EE and can get the quad encoder inputs into the
          Message 4 of 19 , Sep 2, 2008
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            This is just because the servo driver has quad encoder inputs and
            stepper motor drivers do not. I'm a retired EE and can get the quad
            encoder inputs into the computer via another parallel port, so that's
            not a problem.

            Your servo/quad encoder setup would have to have code added to the
            TurboCNC program to actually do something with the feedback from the
            encoder.


            --- In turbocnc@yahoogroups.com, Paul Castellese <pcastellese@...>
            wrote:
            >
            >                    I have servo motors set up that way, but you
            need servo drivers to run them.
            >
            > --- On Mon, 9/1/08, sjblair4 <sjblair4@...> wrote:
            >
            > From: sjblair4 <sjblair4@...>
            > Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ axis
            > To: turbocnc@yahoogroups.com
            > Date: Monday, September 1, 2008, 9:33 PM
            >
            >
            >
            >
            >
            >
            > Has anyone added quadrature encoders to each axis stepper motor to
            use
            > them as a missed step detector, and made the system closed-loop
            like
            > MaxCNC?
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            > [Non-text portions of this message have been removed]
            >
          • das_innere_ich
            ... You can actually close the loop between the driver and motor and leave the controller out. Closing the loop on a stepping motor is harder then on a servo
            Message 5 of 19 , Sep 8, 2008
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              --- In turbocnc@yahoogroups.com, "sjblair4" <sjblair4@...> wrote:
              >
              > This is just because the servo driver has quad encoder inputs and
              > stepper motor drivers do not. I'm a retired EE and can get the quad
              > encoder inputs into the computer via another parallel port, so that's
              > not a problem.
              >
              > Your servo/quad encoder setup would have to have code added to the
              > TurboCNC program to actually do something with the feedback from the
              > encoder.
              >
              >
              > --- In turbocnc@yahoogroups.com, Paul Castellese <pcastellese@>
              > wrote:
              > >
              > >                    I have servo motors set up that way, but you
              > need servo drivers to run them.
              > >
              > > --- On Mon, 9/1/08, sjblair4 <sjblair4@> wrote:
              > >
              > > From: sjblair4 <sjblair4@>
              > > Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ axis
              > > To: turbocnc@yahoogroups.com
              > > Date: Monday, September 1, 2008, 9:33 PM
              > >
              > >
              > >
              > >
              > >
              > >
              > > Has anyone added quadrature encoders to each axis stepper motor to
              > use
              > > them as a missed step detector, and made the system closed-loop
              > like
              > > MaxCNC?
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > > [Non-text portions of this message have been removed]
              > >
              >

              You can actually close the loop between the driver and motor and leave
              the controller out. Closing the loop on a stepping motor is harder
              then on a servo motor, and it should only be used to check for lost steps.

              You can make a controller that keeps track of how many steps it has
              taken and how many steps it should take. You have one register that
              keeps track of how many steps it has to take (step register), and
              whenever it recieves a step from the computer, it will increment this
              register (right away the motor should move, if it is free to do so).
              When the step has been made, it decrements the register again. If
              there is something blocking the motor, it can tell the controller to
              take 18 more steps (assuming you are using a driver with 10
              microsteps) without loosing a step. At this point you can either send
              an error signal to the computer or you can keep track of how many
              steps you have to take (in the step register) to get to the desired
              possition, and so when the motor is free to move again, it will move
              to the commanded possition. Mariss from geckodrive.com is working on a
              driver like this.
            • sjblair4
              ... quad ... that s ... the ... the ... axis ... to ... leave ... steps. ... this ... send ... on a ... This is exactly what I want. Is there going to be a
              Message 6 of 19 , Sep 8, 2008
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                --- In turbocnc@yahoogroups.com, "das_innere_ich" <tommy.ramberg@...>
                wrote:
                >
                > --- In turbocnc@yahoogroups.com, "sjblair4" <sjblair4@> wrote:
                > >
                > > This is just because the servo driver has quad encoder inputs and
                > > stepper motor drivers do not. I'm a retired EE and can get the
                quad
                > > encoder inputs into the computer via another parallel port, so
                that's
                > > not a problem.
                > >
                > > Your servo/quad encoder setup would have to have code added to
                the
                > > TurboCNC program to actually do something with the feedback from
                the
                > > encoder.
                > >
                > >
                > > --- In turbocnc@yahoogroups.com, Paul Castellese <pcastellese@>
                > > wrote:
                > > >
                > > >                    I have servo motors set up that way, but you
                > > need servo drivers to run them.
                > > >
                > > > --- On Mon, 9/1/08, sjblair4 <sjblair4@> wrote:
                > > >
                > > > From: sjblair4 <sjblair4@>
                > > > Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ
                axis
                > > > To: turbocnc@yahoogroups.com
                > > > Date: Monday, September 1, 2008, 9:33 PM
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > > Has anyone added quadrature encoders to each axis stepper motor
                to
                > > use
                > > > them as a missed step detector, and made the system closed-loop
                > > like
                > > > MaxCNC?
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > > [Non-text portions of this message have been removed]
                > > >
                > >
                >
                > You can actually close the loop between the driver and motor and
                leave
                > the controller out. Closing the loop on a stepping motor is harder
                > then on a servo motor, and it should only be used to check for lost
                steps.
                >
                > You can make a controller that keeps track of how many steps it has
                > taken and how many steps it should take. You have one register that
                > keeps track of how many steps it has to take (step register), and
                > whenever it recieves a step from the computer, it will increment
                this
                > register (right away the motor should move, if it is free to do so).
                > When the step has been made, it decrements the register again. If
                > there is something blocking the motor, it can tell the controller to
                > take 18 more steps (assuming you are using a driver with 10
                > microsteps) without loosing a step. At this point you can either
                send
                > an error signal to the computer or you can keep track of how many
                > steps you have to take (in the step register) to get to the desired
                > possition, and so when the motor is free to move again, it will move
                > to the commanded possition. Mariss from geckodrive.com is working
                on a
                > driver like this.
                >

                This is exactly what I want. Is there going to be a plug-in for
                Mach 3 and what about the interface between the encoders and the PC?
              • sjblair4
                ... and ... from ... you ... motor ... loop ... lost ... has ... that ... so). ... to ... desired ... move ... I meant TurboCNC not Mach 3.
                Message 7 of 19 , Sep 8, 2008
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                  --- In turbocnc@yahoogroups.com, "sjblair4" <sjblair4@...> wrote:
                  >
                  > --- In turbocnc@yahoogroups.com, "das_innere_ich" <tommy.ramberg@>
                  > wrote:
                  > >
                  > > --- In turbocnc@yahoogroups.com, "sjblair4" <sjblair4@> wrote:
                  > > >
                  > > > This is just because the servo driver has quad encoder inputs
                  and
                  > > > stepper motor drivers do not. I'm a retired EE and can get the
                  > quad
                  > > > encoder inputs into the computer via another parallel port, so
                  > that's
                  > > > not a problem.
                  > > >
                  > > > Your servo/quad encoder setup would have to have code added to
                  > the
                  > > > TurboCNC program to actually do something with the feedback
                  from
                  > the
                  > > > encoder.
                  > > >
                  > > >
                  > > > --- In turbocnc@yahoogroups.com, Paul Castellese <pcastellese@>
                  > > > wrote:
                  > > > >
                  > > > >                    I have servo motors set up that way, but
                  you
                  > > > need servo drivers to run them.
                  > > > >
                  > > > > --- On Mon, 9/1/08, sjblair4 <sjblair4@> wrote:
                  > > > >
                  > > > > From: sjblair4 <sjblair4@>
                  > > > > Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ
                  > axis
                  > > > > To: turbocnc@yahoogroups.com
                  > > > > Date: Monday, September 1, 2008, 9:33 PM
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > > Has anyone added quadrature encoders to each axis stepper
                  motor
                  > to
                  > > > use
                  > > > > them as a missed step detector, and made the system closed-
                  loop
                  > > > like
                  > > > > MaxCNC?
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > > [Non-text portions of this message have been removed]
                  > > > >
                  > > >
                  > >
                  > > You can actually close the loop between the driver and motor and
                  > leave
                  > > the controller out. Closing the loop on a stepping motor is harder
                  > > then on a servo motor, and it should only be used to check for
                  lost
                  > steps.
                  > >
                  > > You can make a controller that keeps track of how many steps it
                  has
                  > > taken and how many steps it should take. You have one register
                  that
                  > > keeps track of how many steps it has to take (step register), and
                  > > whenever it recieves a step from the computer, it will increment
                  > this
                  > > register (right away the motor should move, if it is free to do
                  so).
                  > > When the step has been made, it decrements the register again. If
                  > > there is something blocking the motor, it can tell the controller
                  to
                  > > take 18 more steps (assuming you are using a driver with 10
                  > > microsteps) without loosing a step. At this point you can either
                  > send
                  > > an error signal to the computer or you can keep track of how many
                  > > steps you have to take (in the step register) to get to the
                  desired
                  > > possition, and so when the motor is free to move again, it will
                  move
                  > > to the commanded possition. Mariss from geckodrive.com is working
                  > on a
                  > > driver like this.
                  > >
                  >
                  > This is exactly what I want. Is there going to be a plug-in for
                  > Mach 3 and what about the interface between the encoders and the PC?
                  >

                  I meant TurboCNC not Mach 3.
                • das_innere_ich
                  ... It s simply going to be a stepping motor driver with a rotary encoder for the motor. So you connect the driver to a breakout board as you would with a
                  Message 8 of 19 , Sep 8, 2008
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                    --- In turbocnc@yahoogroups.com, "sjblair4" <sjblair4@...> wrote:
                    >
                    > --- In turbocnc@yahoogroups.com, "sjblair4" <sjblair4@> wrote:
                    > >
                    > > --- In turbocnc@yahoogroups.com, "das_innere_ich" <tommy.ramberg@>
                    > > wrote:
                    > > >
                    > > > --- In turbocnc@yahoogroups.com, "sjblair4" <sjblair4@> wrote:
                    > > > >
                    > > > > This is just because the servo driver has quad encoder inputs
                    > and
                    > > > > stepper motor drivers do not. I'm a retired EE and can get the
                    > > quad
                    > > > > encoder inputs into the computer via another parallel port, so
                    > > that's
                    > > > > not a problem.
                    > > > >
                    > > > > Your servo/quad encoder setup would have to have code added to
                    > > the
                    > > > > TurboCNC program to actually do something with the feedback
                    > from
                    > > the
                    > > > > encoder.
                    > > > >
                    > > > >
                    > > > > --- In turbocnc@yahoogroups.com, Paul Castellese <pcastellese@>
                    > > > > wrote:
                    > > > > >
                    > > > > >                    I have servo motors set up that way, but
                    > you
                    > > > > need servo drivers to run them.
                    > > > > >
                    > > > > > --- On Mon, 9/1/08, sjblair4 <sjblair4@> wrote:
                    > > > > >
                    > > > > > From: sjblair4 <sjblair4@>
                    > > > > > Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ
                    > > axis
                    > > > > > To: turbocnc@yahoogroups.com
                    > > > > > Date: Monday, September 1, 2008, 9:33 PM
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > > Has anyone added quadrature encoders to each axis stepper
                    > motor
                    > > to
                    > > > > use
                    > > > > > them as a missed step detector, and made the system closed-
                    > loop
                    > > > > like
                    > > > > > MaxCNC?
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > > [Non-text portions of this message have been removed]
                    > > > > >
                    > > > >
                    > > >
                    > > > You can actually close the loop between the driver and motor and
                    > > leave
                    > > > the controller out. Closing the loop on a stepping motor is harder
                    > > > then on a servo motor, and it should only be used to check for
                    > lost
                    > > steps.
                    > > >
                    > > > You can make a controller that keeps track of how many steps it
                    > has
                    > > > taken and how many steps it should take. You have one register
                    > that
                    > > > keeps track of how many steps it has to take (step register), and
                    > > > whenever it recieves a step from the computer, it will increment
                    > > this
                    > > > register (right away the motor should move, if it is free to do
                    > so).
                    > > > When the step has been made, it decrements the register again. If
                    > > > there is something blocking the motor, it can tell the controller
                    > to
                    > > > take 18 more steps (assuming you are using a driver with 10
                    > > > microsteps) without loosing a step. At this point you can either
                    > > send
                    > > > an error signal to the computer or you can keep track of how many
                    > > > steps you have to take (in the step register) to get to the
                    > desired
                    > > > possition, and so when the motor is free to move again, it will
                    > move
                    > > > to the commanded possition. Mariss from geckodrive.com is working
                    > > on a
                    > > > driver like this.
                    > > >
                    > >
                    > > This is exactly what I want. Is there going to be a plug-in for
                    > > Mach 3 and what about the interface between the encoders and the PC?
                    > >
                    >
                    > I meant TurboCNC not Mach 3.
                    >

                    It's simply going to be a stepping motor driver with a rotary encoder
                    for the motor. So you connect the driver to a breakout board as you
                    would with a normal stepping motor driver. You might have the option
                    of including a fault line to check for missed steps.

                    I don't know when he will be done with these drivers, so until then
                    you might just have to live with what you have or design one on your
                    own. I'm designing my own because I have the drivers and motors. Don't
                    want to spend more money on drivers again. And I will only check for
                    missing steps, and not as a closed loop system.
                  • Roland Jollivet
                    Hi It s unlikey there ll be any software changes to TurboCNC, there has not been for the last ?? 6 years or so. You d be better off implementing an external
                    Message 9 of 19 , Sep 8, 2008
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                      Hi

                      It's unlikey there'll be any software changes to TurboCNC, there has not
                      been for the last ?? 6 years or so.
                      You'd be better off implementing an external loop with a Pic or similar.

                      Regards
                      Roland


                      2008/9/8 sjblair4 <sjblair4@...>

                      > -
                      > >
                      > > This is exactly what I want. Is there going to be a plug-in for
                      > > Mach 3 and what about the interface between the encoders and the PC?
                      >



                      >
                      > >I meant TurboCNC not Mach 3.
                      >


                      >
                      >
                      > _
                      >
                      >
                      >
                      >


                      [Non-text portions of this message have been removed]
                    • DA. Forsyth
                      ... Mach 3 doesn t need to know about it. this is (and should be) a hardware solution. the hardware driver is told to make 10000 steps. it keeps track of
                      Message 10 of 19 , Sep 9, 2008
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                        On 8 Sep 2008 at 15:44, sjblair4 murmured decisively:

                        > > You can make a controller that keeps track of how many steps it has
                        > > taken and how many steps it should take. You have one register that
                        > > keeps track of how many steps it has to take (step register), and
                        > > whenever it recieves a step from the computer, it will increment
                        > this
                        > > register (right away the motor should move, if it is free to do so).
                        > > When the step has been made, it decrements the register again. If
                        > > there is something blocking the motor, it can tell the controller to
                        > > take 18 more steps (assuming you are using a driver with 10
                        > > microsteps) without loosing a step. At this point you can either
                        > send
                        > > an error signal to the computer or you can keep track of how many
                        > > steps you have to take (in the step register) to get to the desired
                        > > possition, and so when the motor is free to move again, it will move
                        > > to the commanded possition. Mariss from geckodrive.com is working
                        > on a
                        > > driver like this.
                        > >
                        >
                        > This is exactly what I want. Is there going to be a plug-in for
                        > Mach 3 and what about the interface between the encoders and the PC?

                        Mach 3 doesn't need to know about it. this is (and should be) a hardware
                        solution. the hardware driver is told to make 10000 steps. it keeps
                        track of what the motor actually does and comes up with 1 short, so it
                        drives the motor one more step. problem solved.

                        one might have an error signal coming back to the PC, but what could that
                        do? just act as emergency stop I think. so maybe it should count
                        missing steps and only trigger a stop when the number missing goes over a
                        threshhold. this would indicate when the machine has really crashed into
                        a clamp or whatever.


                        --
                        David http://iwr.ru.ac.za/~iwdf/
                        Size matters, so this signature is short.
                      • Roland Jollivet
                        Otherwise, if you re going to go this much trouble on a stepper, rather just built a DC motor servo drive, using your encoder. No more lost steps, faster....
                        Message 11 of 19 , Sep 9, 2008
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                          Otherwise, if you're going to go this much trouble on a stepper, rather just
                          built a DC motor servo drive, using your encoder. No more lost steps,
                          faster....

                          Regards
                          Roland


                          2008/9/9 DA. Forsyth <notLeftBehind@...>

                          > On 8 Sep 2008 at 15:44, sjblair4 murmured decisively:
                          >
                          >
                          > > > You can make a controller that keeps track of how many steps it has
                          > > > taken and how many steps it should take. You have one register that
                          > > > keeps track of how many steps it has to take (step register), and
                          > > > whenever it recieves a step from the computer, it will increment
                          > > this
                          > > > register (right away the motor should move, if it is free to do so).
                          > > > When the step has been made, it decrements the register again. If
                          > > > there is something blocking the motor, it can tell the controller to
                          > > > take 18 more steps (assuming you are using a driver with 10
                          > > > microsteps) without loosing a step. At this point you can either
                          > > send
                          > > > an error signal to the computer or you can keep track of how many
                          > > > steps you have to take (in the step register) to get to the desired
                          > > > possition, and so when the motor is free to move again, it will move
                          > > > to the commanded possition. Mariss from geckodrive.com is working
                          > > on a
                          > > > driver like this.
                          > > >
                          > >
                          > > This is exactly what I want. Is there going to be a plug-in for
                          > > Mach 3 and what about the interface between the encoders and the PC?
                          >
                          > Mach 3 doesn't need to know about it. this is (and should be) a hardware
                          > solution. the hardware driver is told to make 10000 steps. it keeps
                          > track of what the motor actually does and comes up with 1 short, so it
                          > drives the motor one more step. problem solved.
                          >
                          > one might have an error signal coming back to the PC, but what could that
                          > do? just act as emergency stop I think. so maybe it should count
                          > missing steps and only trigger a stop when the number missing goes over a
                          > threshhold. this would indicate when the machine has really crashed into
                          > a clamp or whatever.
                          >
                          > --
                          > David http://iwr.ru.ac.za/~iwdf/ <http://iwr.ru.ac.za/%7Eiwdf/>
                          > Size matters, so this signature is short.
                          >
                          >
                          >


                          [Non-text portions of this message have been removed]
                        • Fred Savage
                          I have just replaced the Z-axis lead screw nut with one that has more friction and a whole lot less play than the original one. Now, when I first press the
                          Message 12 of 19 , Sep 9, 2008
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                            I have just replaced the Z-axis lead screw nut with one that has more friction and a whole lot less play than the original one. Now, when I first press the key for motion on that axis, I hear what sounds like a grinding noise for a few milliseconds and then the motor runs like normal (quiet and smooth). I can reverse the direction back and forth and the motor continues to run like normal. It seems that if I let the controller go into it's power down mode and then start the motor again, there is the grinding noise again. I can't tell but I think it is also losing steps. Do I need to adjust the ramp up speed or something like that?

                            I appreciate any assistance. BTW, this is all on a HobbyCNC plans table, running HobbyCNC motors and a HobbyCNC Pro controller using Mach3 software.

                            Bob Corder
                            _________________________________________________________________
                            See how Windows connects the people, information, and fun that are part of your life.
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                          • dgoadby
                            Hi Bob, At first glance it seems that the start-up torque on your new Z-axis is a lot higher than the old one. The sound you are hearing may be the stepper
                            Message 13 of 19 , Sep 9, 2008
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                              Hi Bob,

                              At first glance it seems that the start-up torque on your new Z-axis
                              is a lot higher than the old one. The sound you are hearing may be the
                              stepper cogging as it comes up to speed. I would increase the z-axis
                              ramp-up time until it sounds sweeter and, I suspect, no longer losing
                              steps.

                              Regards

                              David

                              --- In turbocnc@yahoogroups.com, Fred Savage <anonzonefly@...> wrote:
                              >
                              >
                              > I have just replaced the Z-axis lead screw nut with one that has
                              more friction and a whole lot less play than the original one. Now,
                              when I first press the key for motion on that axis, I hear what sounds
                              like a grinding noise for a few milliseconds and then the motor runs
                              like normal (quiet and smooth). I can reverse the direction back and
                              forth and the motor continues to run like normal. It seems that if I
                              let the controller go into it's power down mode and then start the
                              motor again, there is the grinding noise again. I can't tell but I
                              think it is also losing steps. Do I need to adjust the ramp up speed
                              or something like that?
                              >
                              > I appreciate any assistance. BTW, this is all on a HobbyCNC plans
                              table, running HobbyCNC motors and a HobbyCNC Pro controller using
                              Mach3 software.
                              >
                              > Bob Corder
                              > _________________________________________________________________
                              > See how Windows connects the people, information, and fun that are
                              part of your life.
                              > http://clk.atdmt.com/MRT/go/msnnkwxp1020093175mrt/direct/01/
                              >
                              > [Non-text portions of this message have been removed]
                              >
                            • David Forsyth
                              ... you need to raise the minimum start speed, I think. the motor is oscillating and probably losing steps. ... -- David
                              Message 14 of 19 , Sep 9, 2008
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                                Fred Savage wrote:

                                > I have just replaced the Z-axis lead screw nut with one that has more
                                > friction and a whole lot less play than the original one. Now, when
                                > I first press the key for motion on that axis, I hear what sounds
                                > like a grinding noise for a few milliseconds and then the motor runs
                                > like normal (quiet and smooth). I can reverse the direction back and
                                > forth and the motor continues to run like normal. It seems that if I
                                > let the controller go into it's power down mode and then start the
                                > motor again, there is the grinding noise again. I can't tell but I
                                > think it is also losing steps. Do I need to adjust the ramp up speed
                                > or something like that?

                                you need to raise the minimum start speed, I think. the motor is
                                oscillating and probably losing steps.

                                > I appreciate any assistance. BTW, this is all on a HobbyCNC plans
                                > table, running HobbyCNC motors and a HobbyCNC Pro controller using
                                > Mach3 software.


                                --
                                David http://iwr.ru.ac.za/~iwdf/
                                If you receive email saying "Send this to everyone you know",
                                PLEASE pretend you don't know me.
                              • Fred Savage
                                Thanks folks. I finally got a chance to tweak my system a little this afternoon and it has helped with the grinding noise as you suggested. It appears that
                                Message 15 of 19 , Sep 9, 2008
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                                  Thanks folks. I finally got a chance to tweak my system a little this afternoon and it has helped with the grinding noise as you suggested. It appears that about the best resolution I can get with this setup is within +/- .0625". I run the cutter out to a point several inches away from zero, i.e. G0 x2.500 y2.500 and it does so but when I return to zero, the DRO reads 0.000 but the cutter is physically past zero by about .0625 and if I repeat the g-command again, it comes up short about .0625 and now when I return to zero, it returns to the original zero + .125". The machine will continue to increase each time so I suspect I am losing steps on the return cycle. More tweaking?

                                  Bob




                                  To: turbocnc@yahoogroups.comFrom: david@...: Tue, 9 Sep 2008 16:39:17 +0000Subject: [turbocnc] Re: Grinding noise.




                                  Hi Bob,At first glance it seems that the start-up torque on your new Z-axisis a lot higher than the old one. The sound you are hearing may be thestepper cogging as it comes up to speed. I would increase the z-axisramp-up time until it sounds sweeter and, I suspect, no longer losingsteps.RegardsDavid--- In turbocnc@yahoogroups.com, Fred Savage <anonzonefly@...> wrote:>> > I have just replaced the Z-axis lead screw nut with one that hasmore friction and a whole lot less play than the original one. Now,when I first press the key for motion on that axis, I hear what soundslike a grinding noise for a few milliseconds and then the motor runslike normal (quiet and smooth). I can reverse the direction back andforth and the motor continues to run like normal. It seems that if Ilet the controller go into it's power down mode and then start themotor again, there is the grinding noise again. I can't tell but Ithink it is also losing steps. Do I need to adjust the ramp up speedor something like that?> > I appreciate any assistance. BTW, this is all on a HobbyCNC planstable, running HobbyCNC motors and a HobbyCNC Pro controller usingMach3 software.> > Bob Corder> __________________________________________________________> See how Windows connects the people, information, and fun that arepart of your life.> http://clk.atdmt.com/MRT/go/msnnkwxp1020093175mrt/direct/01/> > [Non-text portions of this message have been removed]>





                                  _________________________________________________________________
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                                  [Non-text portions of this message have been removed]
                                • dgoadby
                                  Hi Bob, You say the best resolution you can get is +/- 0.0625. For my system that would be a lot and would be unacceptable. However, I don t know your system
                                  Message 16 of 19 , Sep 9, 2008
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                                    Hi Bob,

                                    You say the best resolution you can get is +/- 0.0625. For my system
                                    that would be a lot and would be unacceptable. However, I don't know
                                    your system so it would help if you could you tell us the stepper
                                    motor/ball screw set-up.

                                    Is your Z axis are you moving the tool/machine head or the table? The
                                    weight of either means that going up and going down will have
                                    different characteristics.

                                    Is the ball screw a high quality item with ground screw or hobby
                                    quality with a rolled screw? The reason I ask is the last rolled
                                    ballscrew I used got better after about 100 hours of use. It felt like
                                    it had run itself in. The screw seems to have been polished a little
                                    by the balls. The stepper was way oversize so I didn't need to change
                                    the stepper settings.

                                    It sounds like you are progressing which is good news.

                                    Regards

                                    David

                                    --- In turbocnc@yahoogroups.com, Fred Savage <anonzonefly@...> wrote:
                                    >
                                    >
                                    > Thanks folks. I finally got a chance to tweak my system a little
                                    this afternoon and it has helped with the grinding noise as you
                                    suggested. It appears that about the best resolution I can get with
                                    this setup is within +/- .0625". I run the cutter out to a point
                                    several inches away from zero, i.e. G0 x2.500 y2.500 and it does so
                                    but when I return to zero, the DRO reads 0.000 but the cutter is
                                    physically past zero by about .0625 and if I repeat the g-command
                                    again, it comes up short about .0625 and now when I return to zero, it
                                    returns to the original zero + .125". The machine will continue to
                                    increase each time so I suspect I am losing steps on the return cycle.
                                    More tweaking?
                                    >
                                    > Bob
                                    >
                                    >
                                    >
                                    >
                                    > To: turbocnc@...: david@...: Tue, 9 Sep 2008 16:39:17 +0000Subject:
                                    [turbocnc] Re: Grinding noise.
                                    >
                                    >
                                    >
                                    >
                                    > Hi Bob,At first glance it seems that the start-up torque on your new
                                    Z-axisis a lot higher than the old one. The sound you are hearing may
                                    be thestepper cogging as it comes up to speed. I would increase the
                                    z-axisramp-up time until it sounds sweeter and, I suspect, no longer
                                    losingsteps.RegardsDavid--- In turbocnc@yahoogroups.com, Fred Savage
                                    <anonzonefly@> wrote:>> > I have just replaced the Z-axis lead screw
                                    nut with one that hasmore friction and a whole lot less play than the
                                    original one. Now,when I first press the key for motion on that axis,
                                    I hear what soundslike a grinding noise for a few milliseconds and
                                    then the motor runslike normal (quiet and smooth). I can reverse the
                                    direction back andforth and the motor continues to run like normal. It
                                    seems that if Ilet the controller go into it's power down mode and
                                    then start themotor again, there is the grinding noise again. I can't
                                    tell but Ithink it is also losing steps. Do I need to adjust the ramp
                                    up speedor something like that?> > I appreciate any assistance. BTW,
                                    this is all on a HobbyCNC planstable, running HobbyCNC motors and a
                                    HobbyCNC Pro controller usingMach3 software.> > Bob Corder>
                                    __________________________________________________________> See how
                                    Windows connects the people, information, and fun that arepart of your
                                    life.> http://clk.atdmt.com/MRT/go/msnnkwxp1020093175mrt/direct/01/> >
                                    [Non-text portions of this message have been removed]>
                                    >
                                    >
                                    >
                                    >
                                    >
                                    > _________________________________________________________________
                                    > Want to do more with Windows Live? Learn "10 hidden secrets" from Jamie.
                                    >
                                    http://windowslive.com/connect/post/jamiethomson.spaces.live.com-Blog-cns!550F681DAD532637!5295.entry?ocid=TXT_TAGLM_WL_domore_092008
                                    >
                                    > [Non-text portions of this message have been removed]
                                    >
                                  • DA. Forsyth
                                    ... much more tweaking. half your max speed and acceleration rate and test. if that show no lost steps, then set to (oldmax + currentmax)/2 and repeat, going
                                    Message 17 of 19 , Sep 10, 2008
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                                      On 9 Sep 2008 at 18:21, Fred Savage murmured decisively:

                                      >
                                      > Thanks folks. I finally got a chance to tweak my system a little this
                                      > afternoon and it has helped with the grinding noise as you suggested.
                                      > It appears that about the best resolution I can get with this setup is
                                      > within +/- .0625". I run the cutter out to a point several inches
                                      > away from zero, i.e. G0 x2.500 y2.500 and it does so but when I return
                                      > to zero, the DRO reads 0.000 but the cutter is physically past zero by
                                      > about .0625 and if I repeat the g-command again, it comes up short
                                      > about .0625 and now when I return to zero, it returns to the original
                                      > zero + .125". The machine will continue to increase each time so I
                                      > suspect I am losing steps on the return cycle. More tweaking? Bob

                                      much more tweaking. half your max speed and acceleration rate and test.
                                      if that show no lost steps, then set to (oldmax + currentmax)/2 and
                                      repeat, going higher if you don't lose steps, lower if you do.
                                      then do the same for the acceleration rate. to get high acceleration you
                                      may need to lower the max speed again.

                                      a machine should never lose steps in normal operation. for a stepper
                                      setup, this may mean it will be slow, but at least it will be reliable.


                                      --
                                      David http://iwr.ru.ac.za/~iwdf/
                                      Size matters, so this signature is short.
                                    • Fred Savage
                                      Hi folks, I want to thank you very much for taking the time to get me on the right track for tweaking my machine. It is now running at 15 ipm with an
                                      Message 18 of 19 , Sep 10, 2008
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                                        Hi folks,

                                        I want to thank you very much for taking the time to get me on the right track for tweaking my machine. It is now running at 15 ipm with an acceleration of 6.2 and is repeating very nicely. I am now ready to start making little pieces out of big pieces. I'm sorry I couldn't answer the questions about some of the features of my HobbyCNC machine as I did not want to be off topic and have my question summarily discarded. I hope you understand and once again, thank you very much. I really appreciate it.

                                        Bob Corder



                                        To: turbocnc@yahoogroups.comFrom: notLeftBehind@...: Wed, 10 Sep 2008 10:14:50 +0200Subject: RE: [turbocnc] Re: Grinding noise.




                                        On 9 Sep 2008 at 18:21, Fred Savage murmured decisively:> > Thanks folks. I finally got a chance to tweak my system a little this> afternoon and it has helped with the grinding noise as you suggested. > It appears that about the best resolution I can get with this setup is> within +/- .0625". I run the cutter out to a point several inches> away from zero, i.e. G0 x2.500 y2.500 and it does so but when I return> to zero, the DRO reads 0.000 but the cutter is physically past zero by> about .0625 and if I repeat the g-command again, it comes up short> about .0625 and now when I return to zero, it returns to the original> zero + .125". The machine will continue to increase each time so I> suspect I am losing steps on the return cycle. More tweaking? Bob much more tweaking. half your max speed and acceleration rate and test. if that show no lost steps, then set to (oldmax + currentmax)/2 and repeat, going higher if you don't lose steps, lower if you do.then do the same for the acceleration rate. to get high acceleration you may need to lower the max speed again.a machine should never lose steps in normal operation. for a stepper setup, this may mean it will be slow, but at least it will be reliable.--David http://iwr.ru.ac.za/~iwdf/Size matters, so this signature is short.
                                        .





                                        _________________________________________________________________
                                        See how Windows connects the people, information, and fun that are part of your life.
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                                        [Non-text portions of this message have been removed]
                                      • Paul Kiedrowski
                                        Frankly, you do not want to mess with closed loop methods when using stepper motor drives. Rather upgrade to DC brushed or brushless. If you are having
                                        Message 19 of 19 , Sep 11, 2008
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                                          Frankly, you do not want to mess with closed loop methods when using stepper motor drives. Rather upgrade to DC brushed or brushless. If you are having missed steps you probably need to fine tune the combination of drive power, motor size and torque, stepsize, and the mechanics of the machine. At some speed (steps/second) and load almost all stepper systems will exhibit some vibration and/or missed steps.

                                          The best way I've found to solve the issue is to take a variable frequency square wave generator (set to 5V pulses) and input that to the step input on each drive. As you vary the frequency of the generator you can apply varying amounts of load to the motor (grip the ballscrew or whatever) and find out when it skips steps. You'll be able to hear and feel it easily. It may only be a very small range of freqs that don't work.

                                          Fix problems by first changing the drive current (best performance is not always at max current) then swap motors out. Make sure you lower the load inertia by using a good amount of drive reduction (for example via a ballscrew) so the motor can change speed and direction easily regardless of load on the spindle.

                                          By the way, I doubt TurboCNC will EVER be able to read encoders directly since the standard printer port on an ISA bus is too slow to read them (I've tried it).

                                          Hope that helps!
                                          -Paul

                                          --- On Mon, 9/1/08, sjblair4 <sjblair4@...> wrote:

                                          > From: sjblair4 <sjblair4@...>
                                          > Subject: [turbocnc] The Use of Quadrature Encoders on the XYZ axis
                                          > To: turbocnc@yahoogroups.com
                                          > Date: Monday, September 1, 2008, 8:33 PM
                                          > Has anyone added quadrature encoders to each axis stepper
                                          > motor to use
                                          > them as a missed step detector, and made the system
                                          > closed-loop like
                                          > MaxCNC?
                                          >
                                          >
                                          >
                                          > ------------------------------------
                                          >
                                          >
                                          >
                                          > Yahoo! Groups Links
                                          >
                                          >
                                          >
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