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Question about Power Supply for steppers

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  • Dave Hylands
    Hi everyone, First question. What would be an appropriate current rating for a power supply driving 4 Sherline steppers? The Sherline steppers are rated at 2A
    Message 1 of 12 , May 21, 2003
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      Hi everyone,

      First question. What would be an appropriate current rating for a power
      supply driving 4 Sherline steppers?

      The Sherline steppers are rated at 2A per phase, and depending on how the
      motors are being driven, I'm assuming that one or two phases could be active
      at a time.

      The SLA7044 that I'm planning on using for the drivers can be configured to
      drive two phases simultaneously to provide additional torque. Does anybody
      thing that this mode might be required?

      I'm assuming that each stepper also draws pretty much full current whether
      it's moving or not (since you need to hold the axis).

      So, this tells me that if I assume 2A per stepper, that means I need 8A.
      Does this sound right?

      I see MPJA has a 24V 10A transformer for $17.99.

      --
      Dave Hylands
      Vancouver, BC, Canada
      http://www.DaveHylands.com/
    • John Guenther
      I think that sounds about right. I have two of the MPJA 24V 10A transformers in my power supply and they work great. These are nice transformers for the
      Message 2 of 12 , May 21, 2003
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        I think that sounds about right. I have two of the MPJA 24V 10A
        transformers in my power supply and they work great. These are nice
        transformers for the money, and wired in series I am getting a little over
        70 volts to my four CMD-260 drivers.

        John Guenther
        'Ye Olde Pen Maker'
        Sterling, Virginia

        > -----Original Message-----
        > From: Dave Hylands [mailto:dhylands@...]
        > Sent: Wednesday, May 21, 2003 15:15 PM
        > To: SherlineCNC@yahoogroups.com
        > Subject: [SherlineCNC] Question about Power Supply for steppers
        >
        >
        > Hi everyone,
        >
        > First question. What would be an appropriate current rating for a power
        > supply driving 4 Sherline steppers?
        >
        > The Sherline steppers are rated at 2A per phase, and depending on how the
        > motors are being driven, I'm assuming that one or two phases
        > could be active
        > at a time.
        >
        > The SLA7044 that I'm planning on using for the drivers can be
        > configured to
        > drive two phases simultaneously to provide additional torque. Does anybody
        > thing that this mode might be required?
        >
        > I'm assuming that each stepper also draws pretty much full current whether
        > it's moving or not (since you need to hold the axis).
        >
        > So, this tells me that if I assume 2A per stepper, that means I need 8A.
        > Does this sound right?
        >
        > I see MPJA has a 24V 10A transformer for $17.99.
        >
        > --
        > Dave Hylands
        > Vancouver, BC, Canada
        > http://www.DaveHylands.com/
        >
        >
        >
        >
        > To unsubscribe from this group, send an email to:
        > SherlineCNC-unsubscribe@yahoogroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        >
        >
      • Bryan Mumford
        ... No. If you feed 24 volts in, you need fewer amps because the rating of 2 amps is at a much lower voltage. Four amps at 24 volts ought to be fine. Also, I
        Message 3 of 12 , May 21, 2003
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          At 12:14 PM -0700 05-21-03, Dave Hylands wrote:
          >So, this tells me that if I assume 2A per stepper, that means I need 8A.
          >Does this sound right?

          No. If you feed 24 volts in, you need fewer amps because the rating
          of 2 amps is at a much lower voltage. Four amps at 24 volts ought to
          be fine.

          Also, I like to reduce power to the motor when the motor is not
          moving. You don't need a huge holding torque when at rest. I fold
          back the power when at rest. This saves power and helps keep thing
          cooler.
        • Alan Marconett KM6VV
          Hi Dave, That transformer should give you plenty of power! Actually, the motors won t draw that much on a continuous basis. About .66 X is a good rule of
          Message 4 of 12 , May 21, 2003
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            Hi Dave,

            That transformer should give you plenty of power! Actually, the motors
            won't draw that much on a continuous basis. About .66 X is a good rule
            of thumb, according to Mariss (of Gecko fame). You'll find that they
            draw very little when standing still, if you are using a chopper type
            drive. And the transformers can handle a little current surge now and
            then.

            I hadn't heard of the "extra torque" setting for the SLA7044's. Guess
            I'll have to find a data sheet. We ARE talking about running Bipolar,
            aren't we? Half step (or a microstep) is the mode I'd recommend.

            HTH

            Alan KM6VV


            Dave Hylands wrote:
            >
            > Hi everyone,
            >
            > First question. What would be an appropriate current rating for a power
            > supply driving 4 Sherline steppers?
            >
            > The Sherline steppers are rated at 2A per phase, and depending on how the
            > motors are being driven, I'm assuming that one or two phases could be active
            > at a time.
            >
            > The SLA7044 that I'm planning on using for the drivers can be configured to
            > drive two phases simultaneously to provide additional torque. Does anybody
            > thing that this mode might be required?
            >
            > I'm assuming that each stepper also draws pretty much full current whether
            > it's moving or not (since you need to hold the axis).
            >
            > So, this tells me that if I assume 2A per stepper, that means I need 8A.
            > Does this sound right?
            >
            > I see MPJA has a 24V 10A transformer for $17.99.
            >
            > --
            > Dave Hylands
            > Vancouver, BC, Canada
            > http://www.DaveHylands.com/
          • Dave Hylands
            Hi Alan, The SLA7044 is, in fact, a chopper, and it uses PWM to deliver the appropriate current (determined by a resistor).
            Message 5 of 12 , May 21, 2003
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              Hi Alan,

              The SLA7044 is, in fact, a chopper, and it uses PWM to deliver the
              appropriate current (determined by a resistor).
              http://www.allegromicro.com/sf/97042/
              http://www.allegromicro.com/sf/9001/

              The SLA7044's are actually designed for unipolar steppers (which is what the
              Sherline's are) and has the electronics to drive all 4 phases. It also has
              built-in micro-stepping capability (1/2, 1/4 or 1/8 step).

              So, given that it can deliver more current than the motors can take, (the
              7044 is rated upto 3A per phase), I don't see any particular advantage to
              using bipolar (unless of course, I purchase bipolar steppers).

              Which leads to another question. How much current should I set the 7044's to
              deliver to the Sherline steppers? Is it OK to give the steppers the full 2A
              all the time?

              --
              Dave Hylands
              Vancouver, BC, Canada
              http://www.DaveHylands.com/


              -----Original Message-----
              From: Alan Marconett KM6VV [mailto:KM6VV@...]
              Sent: Wednesday, May 21, 2003 1:07 PM
              To: SherlineCNC@yahoogroups.com
              Subject: Re: [SherlineCNC] Question about Power Supply for steppers


              Hi Dave,

              That transformer should give you plenty of power! Actually, the motors
              won't draw that much on a continuous basis. About .66 X is a good rule of
              thumb, according to Mariss (of Gecko fame). You'll find that they draw very
              little when standing still, if you are using a chopper type drive. And the
              transformers can handle a little current surge now and then.

              I hadn't heard of the "extra torque" setting for the SLA7044's. Guess I'll
              have to find a data sheet. We ARE talking about running Bipolar, aren't we?
              Half step (or a microstep) is the mode I'd recommend.

              HTH

              Alan KM6VV


              Dave Hylands wrote:
              >
              > Hi everyone,
              >
              > First question. What would be an appropriate current rating for a
              > power supply driving 4 Sherline steppers?
              >
              > The Sherline steppers are rated at 2A per phase, and depending on how
              > the motors are being driven, I'm assuming that one or two phases could
              > be active at a time.
              >
              > The SLA7044 that I'm planning on using for the drivers can be
              > configured to drive two phases simultaneously to provide additional
              > torque. Does anybody thing that this mode might be required?
              >
              > I'm assuming that each stepper also draws pretty much full current
              > whether it's moving or not (since you need to hold the axis).
              >
              > So, this tells me that if I assume 2A per stepper, that means I need
              > 8A. Does this sound right?
              >
              > I see MPJA has a 24V 10A transformer for $17.99.
              >
              > --
              > Dave Hylands
              > Vancouver, BC, Canada
              > http://www.DaveHylands.com/

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            • John Guenther
              As I understand things, the Sherline steppers can be used in either unipolar or bipolar mode, however the connectors used by Sherline have them hooked up to
              Message 6 of 12 , May 21, 2003
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                As I understand things, the Sherline steppers can be used in either unipolar
                or bipolar mode, however the connectors used by Sherline have them hooked up
                to run in unipolar mode.

                John Guenther
                'Ye Olde Pen Maker'
                Sterling, Virginia

                > -----Original Message-----
                > From: Dave Hylands [mailto:dhylands@...]
                > Sent: Wednesday, May 21, 2003 16:17 PM
                > To: 'SherlineCNC@yahoogroups.com'
                > Subject: RE: [SherlineCNC] Question about Power Supply for steppers
                >
                >
                > Hi Alan,
                >
                > The SLA7044 is, in fact, a chopper, and it uses PWM to deliver the
                > appropriate current (determined by a resistor).
                > http://www.allegromicro.com/sf/97042/
                > http://www.allegromicro.com/sf/9001/
                >
                > The SLA7044's are actually designed for unipolar steppers (which
                > is what the
                > Sherline's are) and has the electronics to drive all 4 phases. It also has
                > built-in micro-stepping capability (1/2, 1/4 or 1/8 step).
                >
                > So, given that it can deliver more current than the motors can take, (the
                > 7044 is rated upto 3A per phase), I don't see any particular advantage to
                > using bipolar (unless of course, I purchase bipolar steppers).
                >
                > Which leads to another question. How much current should I set
                > the 7044's to
                > deliver to the Sherline steppers? Is it OK to give the steppers
                > the full 2A
                > all the time?
                >
                > --
                > Dave Hylands
                > Vancouver, BC, Canada
                > http://www.DaveHylands.com/
                >
                >
                > -----Original Message-----
                > From: Alan Marconett KM6VV [mailto:KM6VV@...]
                > Sent: Wednesday, May 21, 2003 1:07 PM
                > To: SherlineCNC@yahoogroups.com
                > Subject: Re: [SherlineCNC] Question about Power Supply for steppers
                >
                >
                > Hi Dave,
                >
                > That transformer should give you plenty of power! Actually, the motors
                > won't draw that much on a continuous basis. About .66 X is a good rule of
                > thumb, according to Mariss (of Gecko fame). You'll find that
                > they draw very
                > little when standing still, if you are using a chopper type
                > drive. And the
                > transformers can handle a little current surge now and then.
                >
                > I hadn't heard of the "extra torque" setting for the SLA7044's.
                > Guess I'll
                > have to find a data sheet. We ARE talking about running Bipolar,
                > aren't we?
                > Half step (or a microstep) is the mode I'd recommend.
                >
                > HTH
                >
                > Alan KM6VV
                >
                >
                > Dave Hylands wrote:
                > >
                > > Hi everyone,
                > >
                > > First question. What would be an appropriate current rating for a
                > > power supply driving 4 Sherline steppers?
                > >
                > > The Sherline steppers are rated at 2A per phase, and depending on how
                > > the motors are being driven, I'm assuming that one or two phases could
                > > be active at a time.
                > >
                > > The SLA7044 that I'm planning on using for the drivers can be
                > > configured to drive two phases simultaneously to provide additional
                > > torque. Does anybody thing that this mode might be required?
                > >
                > > I'm assuming that each stepper also draws pretty much full current
                > > whether it's moving or not (since you need to hold the axis).
                > >
                > > So, this tells me that if I assume 2A per stepper, that means I need
                > > 8A. Does this sound right?
                > >
                > > I see MPJA has a 24V 10A transformer for $17.99.
                > >
                > > --
                > > Dave Hylands
                > > Vancouver, BC, Canada
                > > http://www.DaveHylands.com/
                >
                > ------------------------ Yahoo! Groups Sponsor
                > ---------------------~--> Get
                > A Free Psychic Reading! Your Online Answer To Life's Important Questions.
                > http://us.click.yahoo.com/aM1XQD/od7FAA/uetFAA/DLTolB/TM
                > ---------------------------------------------------------------------~->
                >
                > To unsubscribe from this group, send an email to:
                > SherlineCNC-unsubscribe@yahoogroups.com
                >
                >
                >
                > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
                >
                >
                >
                >
                > To unsubscribe from this group, send an email to:
                > SherlineCNC-unsubscribe@yahoogroups.com
                >
                >
                >
                > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
                >
                >
              • Bryan Mumford
                ... Yes. Note that the AC adaptor we use for the CNC Rotary Table is rated at 24 volts, one amp. -- Bryan Mumford Santa Barbara, California
                Message 7 of 12 , May 21, 2003
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                  At 1:17 PM -0700 05-21-03, Dave Hylands wrote:
                  > Is it OK to give the steppers the full 2A
                  >all the time?

                  Yes.

                  Note that the AC adaptor we use for the CNC Rotary Table is rated at
                  24 volts, one amp.


                  --

                  Bryan Mumford
                  Santa Barbara, California
                  http://www.bmumford.com
                • Alan Marconett KM6VV
                  Hi John, Yes, now that I recall, they are 6 lead steppers. I connected a set bipolar for use with Gecko s. I wasn t aware that Sherline ran them unipolar.
                  Message 8 of 12 , May 21, 2003
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                    Hi John,

                    Yes, now that I recall, they are 6 lead steppers. I connected a set
                    bipolar for use with Gecko's. I wasn't aware that Sherline ran them
                    unipolar.

                    Alan KM6VV


                    John Guenther wrote:
                    >
                    > As I understand things, the Sherline steppers can be used in either unipolar
                    > or bipolar mode, however the connectors used by Sherline have them hooked up
                    > to run in unipolar mode.
                    >
                    > John Guenther
                    > 'Ye Olde Pen Maker'
                    > Sterling, Virginia
                  • Statman Designs, LLC
                    The improvements in the Xylotex driver over the Camtronics is nothing short of remarkable. It is BETTER in every possible way. I have an extra Camtronics
                    Message 9 of 12 , May 21, 2003
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                      The improvements in the Xylotex driver over the Camtronics is nothing short
                      of remarkable. It is BETTER in every possible way. I have an extra
                      Camtronics 3-axis 2A bipolar chopper driver kit already working and
                      assembled if anyone wants it for $50 plus shipping (Paypal accepted). I
                      like my Xylotex driver so much, I bought a second one for my second
                      Sherline-CNC mill. I will also buy a third for my third mill and a fourth
                      for my fourth one, you get the point.

                      There is absolutely no downside to using the Xylotex driver.

                      Daniel J. Statman, Statman Designs
                      www.statmandesigns.com
                      dan.statman@...


                      ----- Original Message -----
                      From: "Carol & Jerry Jankura" <jerry.jankura@...>
                      To: <SherlineCNC@yahoogroups.com>
                      Sent: Wednesday, May 21, 2003 8:21 PM
                      Subject: RE: [SherlineCNC] Question about Power Supply for steppers


                      > I've got the Camtronics drivers, but am thinking of
                      > buying the Xylotex drivers (Can anyone quantify the improvements of moving
                      > from a half stepping system to an eighth stepping system).
                      >
                      > -- Carol & Jerry Jankura
                      > Strongsville, Ohio
                      > So many toys, So little time ....
                      >
                    • Bryan Mumford
                      ... When we were developing the Sherline CNC driver board we ran it in half stepping mode for a while. The motors make a lot of noise at low speeds. At one
                      Message 10 of 12 , May 21, 2003
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                        At 5:21 PM -0700 05-21-03, Carol & Jerry Jankura wrote:
                        >(Can anyone quantify the improvements of moving
                        >from a half stepping system to an eighth stepping system).

                        When we were developing the Sherline CNC driver board we ran it in
                        half stepping mode for a while. The motors make a lot of noise at low
                        speeds. At one particular speed the resonance became so bad that the
                        motor jumped ahead or behind by several steps in an instant. In our
                        case, this happened around 1.7 inches/minute. It was the same on
                        several different Sherline mills.

                        --

                        Bryan Mumford
                        Santa Barbara, California
                        http://www.bmumford.com
                      • Alan Marconett KM6VV
                        Hi Dave, I d go with the 2A, should be fine. The chopper should automatically cut that down for you, and probably also have a power down or standby holding
                        Message 11 of 12 , May 21, 2003
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                          Hi Dave,

                          I'd go with the 2A, should be fine. The chopper should automatically
                          cut that down for you, and probably also have a power down or "standby"
                          holding mode, which result in lower currents also.

                          Steppers really don't care whether they're unipolar or bipolar, they'll
                          run either way, as long as there are enough wires! Connecting them in
                          parallel bipolar (8 wire motors), however, one will need to reduce the
                          current.

                          1/2 step is fine, and I'd also try 1/4 and 1/8! it'll take a few more
                          steps/min to run them that way, but the result should be smoother
                          operation.

                          Sounds a little like the SL7300's that HP used in their Series II Laser
                          Jet printer.

                          Alan KM6VV


                          Dave Hylands wrote:
                          >
                          > Hi Alan,
                          >
                          > The SLA7044 is, in fact, a chopper, and it uses PWM to deliver the
                          > appropriate current (determined by a resistor).
                          > http://www.allegromicro.com/sf/97042/
                          > http://www.allegromicro.com/sf/9001/
                          >
                          > The SLA7044's are actually designed for unipolar steppers (which is what the
                          > Sherline's are) and has the electronics to drive all 4 phases. It also has
                          > built-in micro-stepping capability (1/2, 1/4 or 1/8 step).
                          >
                          > So, given that it can deliver more current than the motors can take, (the
                          > 7044 is rated upto 3A per phase), I don't see any particular advantage to
                          > using bipolar (unless of course, I purchase bipolar steppers).
                          >
                          > Which leads to another question. How much current should I set the 7044's to
                          > deliver to the Sherline steppers? Is it OK to give the steppers the full 2A
                          > all the time?
                          >
                          > --
                          > Dave Hylands
                          > Vancouver, BC, Canada
                          > http://www.DaveHylands.com/
                          >
                          >
                          > -----Original Message-----
                          > From: Alan Marconett KM6VV [mailto:KM6VV@...]
                          > Sent: Wednesday, May 21, 2003 1:07 PM
                          > To: SherlineCNC@yahoogroups.com
                          > Subject: Re: [SherlineCNC] Question about Power Supply for steppers
                          >
                          > Hi Dave,
                          >
                          > That transformer should give you plenty of power! Actually, the motors
                          > won't draw that much on a continuous basis. About .66 X is a good rule of
                          > thumb, according to Mariss (of Gecko fame). You'll find that they draw very
                          > little when standing still, if you are using a chopper type drive. And the
                          > transformers can handle a little current surge now and then.
                          >
                          > I hadn't heard of the "extra torque" setting for the SLA7044's. Guess I'll
                          > have to find a data sheet. We ARE talking about running Bipolar, aren't we?
                          > Half step (or a microstep) is the mode I'd recommend.
                          >
                          > HTH
                          >
                          > Alan KM6VV
                        • Carol & Jerry Jankura
                          I am using Sherline s steppers in bipolar mode with the Camtronics driver. So, yes, you can use Sherline s drives in either unipolar or bipolar mode. BTW - to
                          Message 12 of 12 , May 21, 2003
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                            I am using Sherline's steppers in bipolar mode with the Camtronics driver.
                            So, yes, you can use Sherline's drives in either unipolar or bipolar mode.

                            BTW - to introduce myself - I'm Jerry Jankura and have a Sherline model 2000
                            mill which I converted over to CNC about a year and a half ago. I'm using
                            Sherline's coupler kit and motors (I wanted double ended motors to be able
                            to use the hand wheels). I've got the Camtronics drivers, but am thinking of
                            buying the Xylotex drivers (Can anyone quantify the improvements of moving
                            from a half stepping system to an eighth stepping system).

                            I'm using an old NCR Pentium MMX computer that I purchased for $30. It runs
                            either Win 98SE or DOS. I'm using TurboCNC as my G-Code interpreter (I'm
                            also working with Dave K on rel 4 of TurboCNC) and Vector as my
                            drawing/G-Code generator.

                            -- Carol & Jerry Jankura
                            Strongsville, Ohio
                            So many toys, So little time ....

                            | As I understand things, the Sherline steppers can be used in
                            | either unipolar
                            | or bipolar mode, however the connectors used by Sherline have
                            | them hooked up
                            | to run in unipolar mode.
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