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  1. #1
    croy's Avatar
    Lives in Cardiff, United Kingdom. Last Activity: 26-09-2012 Has been a member for 6-7 years. Has a total post count of 29.
    Hi, i need some help/advice on setting up stepper drives, Currently trying to CNC my lathe i have a 14mm dia x 4mm pitch ballscrew for the leadscrew and a 8mm dia x 2mm pitch for the cross slide.

    i have a Nema 23 on the leadscrew and a nema 17 on the cross-slide. these are driven MSD542's powered by a 50V DC 10A power supply.

    I have setup the micro drivers to 8 microsteps, Is this possible too much? as the motors sound rough.

    Some background ( i had the drives etc working on the old 8 TPI leadscrew) so there is no problemas with power motors or drivers..

    Thanks
    Roy
    Regards,
    Roy Stark

  2. #2
    Roy,
    Have you tried any other settings ?
    How are you connecting the motors to the screws ? Oldhams or lovejaw type couplings ?
    John S -

  3. #3
    50V supply on 50V drive is bad idea.! . . . your in danger of back emf frying them on de-acceleration. On a lathe it probably won't be a massive issue because it wont be de-accelerating from high feeds but @50V your on the edge.!!

    First I would double, triple check all your wiring, esp the motors phase connections.

    Check your amps are not set too high on drive, then like john says try other settings.

    What model motors are they.?
    How have you got the motors wired.? Parallel or series or unipolar.

  4. #4
    croy's Avatar
    Lives in Cardiff, United Kingdom. Last Activity: 26-09-2012 Has been a member for 6-7 years. Has a total post count of 29.
    I think it is just my settings. as the only thing that changed was to replace the myford leadscrew with a ballscrew.

    coupled with a belt 20 tooth on the motor and 40 tooth on the screw.



    Quote Originally Posted by JAZZCNC View Post
    50V supply on 50V drive is bad idea.! . . . your in danger of back emf frying them on de-acceleration. On a lathe it probably won't be a massive issue because it wont be de-accelerating from high feeds but @50V your on the edge.!!

    First I would double, triple check all your wiring, esp the motors phase connections.

    Check your amps are not set too high on drive, then like john says try other settings.

    What model motors are they.?
    How have you got the motors wired.? Parallel or series or unipolar.
    Regards,
    Roy Stark

  5. #5
    croy's Avatar
    Lives in Cardiff, United Kingdom. Last Activity: 26-09-2012 Has been a member for 6-7 years. Has a total post count of 29.
    Thanks John,

    i been fiddling with the settings in MACH since the screw changed from 8TPI to 4mm pitch. so i am guessing this is the area of problem.


    PS, assembling the PCB this afternoon to test. will keep you posted.

    Quote Originally Posted by John S View Post
    Roy,
    Have you tried any other settings ?
    How are you connecting the motors to the screws ? Oldhams or lovejaw type couplings ?
    Regards,
    Roy Stark

  6. #6
    Try different velocity and acceleration settings in Mach
    John S -

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  8. #7
    Quote Originally Posted by croy View Post
    I think it is just my settings. as the only thing that changed was to replace the myford leadscrew with a ballscrew.

    coupled with a belt 20 tooth on the motor and 40 tooth on the screw.
    Please dont take this wrong way but you have changed the steps per to take into account the gearing.?

  9. #8
    croy's Avatar
    Lives in Cardiff, United Kingdom. Last Activity: 26-09-2012 Has been a member for 6-7 years. Has a total post count of 29.
    Hi No i dont think i have.

    Dont worry i am not offended just grateful for the help
    Regards,
    Roy Stark

  10. #9
    Quote Originally Posted by croy View Post
    Hi No i dont think i have.

    Dont worry i am not offended just grateful for the help
    Well there's your problem then.

    If 1600 micro steps and 4mm pitch with 20T on motor and 40T screw then try 800 in steps per. So formule (micro steps/pitch) * (screw pulley/motor pulley)

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  12. #10
    croy's Avatar
    Lives in Cardiff, United Kingdom. Last Activity: 26-09-2012 Has been a member for 6-7 years. Has a total post count of 29.
    Thanks, i am going to finish watching the rugby, then i'll give it another try.

    Quote Originally Posted by JAZZCNC View Post
    Well there's your problem then.

    If 1600 micro steps and 4mm pitch with 20T on motor and 40T screw then try 800 in steps per. So formule (micro steps/pitch) * (screw pulley/motor pulley)
    Regards,
    Roy Stark

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