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  1. #101
    diycnc's Avatar
    Lives in Manchester, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 6-7 years. Has a total post count of 66. Received thanks 2 times, giving thanks to others 11 times.
    Quote Originally Posted by AndyUK View Post
    That might be why things are sounding loud. Are they lubricated well?
    Not at all! Just the sticky grease they come with at he moment. Pretty sure the noise is just the motor vibration on the metal frame, not the screw. Might try taking the belt off tonight to test without any load.
    Last edited by diycnc; 05-12-2019 at 09:49 AM.

  2. #102
    Quote Originally Posted by diycnc View Post
    Not at all! Just the sticky grease they come with at he moment. Pretty sure the noise is just the motor vibration on the metal frame, not the screw. Might try taking the belt off tonight to test without any load.
    This vibration could be causing resonance which will affect the performance.

    However, at 5Mtr/min your close to reaching the limit and other factors will come into play so resonance could be clipping your wings a little.
    Also depending on the controller then you might be better off dropping the micro-stepping. When reaching limits the controller and quality of pulses starts to play its part.

    With 68V and digital drives on a machine with decent rails, aligned and set up correctly with average gantry weight of 30-50kg then I'd expect to top out around 7mtr/min with 5mm pitch. I would tune to run at 5mtr/min.

  3. #103
    diycnc's Avatar
    Lives in Manchester, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 6-7 years. Has a total post count of 66. Received thanks 2 times, giving thanks to others 11 times.
    Quote Originally Posted by Voicecoil View Post
    If it were me I'd run the enable, pulse and dir. signals as twisted pairs - common the -ve ends up at the Arduino. This approach gives much cleaner waveforms and better resistance to interference.
    Would something like a CAT 6 cable be a good idea?

  4. #104
    Quote Originally Posted by diycnc View Post
    Would something like a CAT 6 cable be a good idea?
    CAT6, CAT5 whatever you have lying about. Try one length of cable per driver with all the screens grounded at the Arduino end as well. If you can keep the cable runs for driver input signals and high current motor outputs separate that helps too.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  5. #105
    diycnc's Avatar
    Lives in Manchester, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 6-7 years. Has a total post count of 66. Received thanks 2 times, giving thanks to others 11 times.
    Had an experiment with micro-stepping today. Increasing micro-stepping reduced noise, and increased the speed before it started skipping steps.
    Im using GRBL for testing, which has a limit of 30kHz, so 1/8 is about as high as I can go and still achieve a sensible speed. Any higher and the Arduino crashes.

    What micro-stepping settings do others tend to use when running Mach 3 or similar from a parallel port?
    The drivers go up to a whopping 1/256!

  6. #106
    A lot depends on the stepper drivers - many max out around 100kHz-200kHz.

    My recent tinkering are with a lathe conversion and I'm settled at 8x, though I'm re-using modified drivers that will take 250kHz

  7. #107
    diycnc's Avatar
    Lives in Manchester, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 6-7 years. Has a total post count of 66. Received thanks 2 times, giving thanks to others 11 times.
    Quote Originally Posted by Doddy View Post
    A lot depends on the stepper drivers - many max out around 100kHz-200kHz.
    These drives are rated to 200khz. Assuming I'm running at max for 5m/min, I could get to 32x with a very healthy margin of safety.

  8. #108
    I'm running Nema 23 / 3Nm steppers driving 2005 ballscrews up to 1000 RPM via 1-1 belt drive giving 5m/min rapids. I use x8 microsteps and it all works fine. General opinion is that somewhere around x8 is the sweet spot between smoother, quieter, motion and losing torque (which happens as you wind up the microsteps). I wouldn't exactly say that my machine purrs but it isn't a bag of nails either!

  9. #109
    Quote Originally Posted by diycnc View Post
    These drives are rated to 200khz. Assuming I'm running at max for 5m/min, I could get to 32x with a very healthy margin of safety.
    Pointless because your motors cannot resolve that low and it just stresses the pulse engine, Also if I'm reading correctly and you are using an Arduino then I'm not sure it can output pulses at this rating.? . . . But i don't know much about them so could be wrong.

    The main reason to up the MS is to give smoother running motor but there is, as always a cost, much past 16x is waste and just stresses out the controller and wastes torque.

  10. #110
    diycnc's Avatar
    Lives in Manchester, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 6-7 years. Has a total post count of 66. Received thanks 2 times, giving thanks to others 11 times.
    The max frequency for a GRBL on an arduino is 30kHz, which effectively limits me to 1/8 anyway.

    I just tried running a motor off the machine, with zero load, and it's 50:50 if it will run at 900rpm, which is only equivalent to 4.5m/min. I can feel the motor start to vibrate as it accelerates up to speed.

    Going to try tidying up the wiring to see if that helps. Got twisted pair for the control side. For the motor side, this might be a silly question, should I run all 8 wires all the way to the driver and connect the pairs there, or join the pairs close to the motor and just run 4 wires from there. For the purpose of testing I'm not using shielded cables at the moment, would that impact motor performance at all?
    Last edited by diycnc; 17-12-2019 at 11:45 PM.

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