Teknic Clearpath Servo motors installed on a G0704 CNC mill

I recently upgraded my mill to use Clearpath Servo motors. The motors I used are the CPM-SDSK-2341S-RLN which are 828 oz-in of torque.

The motors run really well. They are powerful enough for the mill, and are absolutely silent when they run – this was really surprising. I’d never realized how much noise the steppers made.

I swapped out 400 oz-in steppers for these servos. Interestingly, when I first installed the servos, they had trouble moving the table. This was before calibration, and also before I adjusted the power supply to output the full voltage (there’s a selector switch in the power supply for various input voltage levels). Once I adjusted the ways, lubricated the ways, and tuned the motors, the mill ran really well. I’ve been able to do heavy cuts and have never noticed an issue. I’ve been able to speed up the “rapid” speed of the mill to 100 inches/minute, from the previous setting of 40.

Teknic states that the servos can be one-half the rated torque of a stepper motor, but I’m skeptical, based on my experience.

The servos each have a USB port, and come with a windows application for tuning the motors. When the application runs, you can see the torque, maximum torque, speed, direction, etc. In the tuning mode, you first define a range of motion for the motors – say a 20 to 50 turn range where the motor can run safely. Then it enters a tuning mode where it applies different levels of torque, moves the mill slowly and quickly in each direction, and does loud jarring movements where the motor slams the shaft. It does this to analyse the resonance of the machine. It is scary to watch. It’s like your mill is being hammered with a sledge hammer! In fact, it loosened the set screws on the Lovejoy connectors (which were too small anyway).  The tuning takes about 20 minutes per axis.

19 thoughts on “Teknic Clearpath Servo motors installed on a G0704 CNC mill

  1. florian

    Hi there,
    after a 3 month wait and i finally received my cmp- sdsk 23 servos.
    ATM however i am struggling with the electric and electronic setup.
    Could you pls claify what wires you conected to achive step and control?
    I am confued about the enable 1 / and 2 and other choices.
    As well i am totally unsure about polarity. At the end of the document (quick start) they show pins 1 and 3 opposite of the drawing right at the beginning of the document ( aprox page 3)
    As i am no OEM clearpath denies any support and i am not a native english speaker.
    Any help will be great.



    1. rich Post author

      Hi Flo,
      I hooked it up according to this guide:
      The motors have a lot of modes. I used SD motors – Step and Direction. This is described on page 81 of the pdf.
      Input A is direction. High= CW.
      Input B is step.
      Enable is High to enable.
      Ground the A- and B- pins.
      You need to connect power as well of course.
      Try the motors with the Clearpath app and the USB connection. You’ll need this to calibrate the motor. It is great for testing and error notifications as well.

      1. florian

        thx so far.
        i am trying to use them as Step and Direktion as well. Just replacing my old steppers.
        Well, on a Breakout Board one does usually connect 4 wires leading to each motor with the board.
        If i got you and the manual right i am now using Black/white and green/?? (sorry forgot) – or input 1 and 2 – of the eight pins, ignoring HBFL and enable…?

        Thanks again.


        1. rich Post author

          Hi Flo,
          With the clearpath servo motors you DON’T use a motor driver. You connect the step and direction and enable directly to the output of your controller, which could be the parallel port of a PC if you are using Mach3, or for example, could be the output pins of a planet-cnc.com controller. You will also need to connect the high current power supply to the servo motors instead of to the motor driver board.
          Here’s a video from NEO7CNC about this:

  2. florian

    that helped a lot.

    Getting closer…
    just need to figure out if i do have to or even can connect the hlfb to my bob.



  3. florian

    Hi again
    Finally got my powersuply and was able to run the servos using the usb device.
    Fantastic smooth moves and the quietness!!

    However i cannot “autotune”them, well i can but it starts from 0-41% doing nothing apparently (no move at all) and then freezes apparently at 41%. Well -it stays at 41 for as long as 12 mins until i discontinued.
    Do i reallyneed to tune them? or could i just run them using a setup file i am able to save ( like 1000 rpm/ 90% troque, 1200 accell.. and so on – just figures from air)
    Did you tune yours? did the servos move right from the beginning?
    should i just use mach 3 and configure it and see what happens?
    any thoughts?



    1. rich Post author

      Hi Florian,
      I would try to get the autotune to work. There were some steps to make it work – you had to agree to some dialog or other, and you have to move the motor to a safe start and end position, so the motor knows a safe range of movement. I would contact the manufacturer directly for help with this.
      The auto-tune was quite something to watch. It went for a long time, and did some incredible things with the machine. It moved slowly, quickly, and it moved with incredibly strong jerk motions – it made a noise like I was hammering on the mill with a sledge hammer. It does this to learn about how much each axis vibrates and resonates, so it can determine how quickly to move them.
      Each axis is different, with different settings.
      I would try to get the auto-tune to work.

      1. florian

        still cannot get them to autotune… they just do …nothing till 41% then it seems to timeout.
        I can move them via mach as well as via the usb/MSP but they do not have any torque at all.
        I can actually stop my spindle (2nm Servo!!) using 3 fingers!!
        50V Powersupply as per spec, all motors green blinks…

        As for now i have tried 6 different computers and no change.

        Quite anoying to have 1000 dollars worth of trash.
        No support of Teknic…

        What to do?
        Any idea?



  4. Tom Tullar

    Florian was using a German operating system which prevented the auto-tuner to function properly. Once he changed the regional code to USA the auto-tuner functioned flawlessly and he has very smooth motion.

      1. rich Post author

        Yes, the regional code in Windows. For tuning say that you are in the US. This may have been fixed in a newer version. I’m not sure.

        1. seng ju

          I yesterday try change can work for finish tuning 1 time.
          But the result very bad.
          Today again tuning but no work anymore.
          Normally how long yours tuning time?

  5. Bob

    I’m interested in your motor mount brackets, drive screws, controller hardware and software, and any other details you’d like to publish. Also, did you do any spindle changes?

    1. rich Post author

      I bought the 75 volt supply straight from Clearpath. It wants to be a beefy linear supply I believe. Not a switching supply. This way it has the extra current on standby essentially, stored in big capacitors.

  6. Arie

    Dynamic Braking ClearPath can be configured to use its regenerated enegy as a source to stop its own motion in cases where the motor is disabled by the user or if it shuts down due to an error condition.

  7. István SZABÓ

    It might be off the topic but hope someone can advise… I’m setting up an old manual lathe retrofitted with Clearpath servos and PlanetCNC controller. Basically it is working but I can not figure out how to enable the servos when starting up the system. I have to do it from Clear view setup program then drive with PlanetCNC. I hope I could do it within PlanetCNC. Is there particular setting from Clear Path MSP should be made?

      1. István SZABÓ

        Thanks for reply.
        I have tried but not working. I did checked on the controller the enable have the 5V properly… Non of the two servos are reacting to the enable signal. I will try with Teknic’s tech support.


Leave a Reply

Your email address will not be published. Required fields are marked *