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  1. #1
    Member
    Join Date
    Oct 2012
    Posts
    7

    no holding torque

    i have these steppers: https://www.automationtechnologiesin...l23h286-20-8b/

    and these drivers: https://www.automationtechnologiesin...rivers/kl5056/

    i wired them bipolar parallel and have 36v power supply.

    they run as they should, but it is pretty easy to spin the motor shaft when the motor is powered but not moving. it should be hard to turn, right?

    also, they don't get even a little warm. i set the driver at 2.7 amps, but later snuck it up to 4.3 amps, trying to gain some holding torque. still easy to turn the stopped shaft, and still not above room temp.

    thanks for any help.
    calvin.

  2. #2
    Member
    Join Date
    Apr 2004
    Posts
    5420

    Re: no holding torque

    The inductance on those motors in bipolar parallel is 6.8 mH. That means that they really want about 83v to run optimally. Since you're only giving them 36v, you shouldn't really expect too much from them. Those drives will take up to 50vdc; that would be better, but still not great,
    Andrew Werby
    Website

  3. #3
    Registered
    Join Date
    Feb 2008
    Posts
    629

    Re: no holding torque

    Quote Originally Posted by cmitcham View Post
    i have these steppers: https://www.automationtechnologiesin...l23h286-20-8b/

    and these drivers: https://www.automationtechnologiesin...rivers/kl5056/

    i wired them bipolar parallel and have 36v power supply.

    they run as they should, but it is pretty easy to spin the motor shaft when the motor is powered but not moving. it should be hard to turn, right?

    also, they don't get even a little warm. i set the driver at 2.7 amps, but later snuck it up to 4.3 amps, trying to gain some holding torque. still easy to turn the stopped shaft, and still not above room temp.

    thanks for any help.
    calvin.
    Do you have SW4 on? if its off, the motor current will be reduced by 1/2 when idle

  4. #4
    Member
    Join Date
    Oct 2012
    Posts
    7

    Re: no holding torque

    i learned (after buying) that inductance is a spec i need to watch, but from what i read, lower voltage should only hurt me speed-wise, not holding torque. or have i got that wrong also?

    i have tried sw4 both ways, since i am easily confused when 1=off and 0=on

    thanks guys, still wondering if i can try bumping up the current without hurting anything since nothing is hot yet.

  5. #5
    Registered
    Join Date
    Apr 2005
    Posts
    554

    Re: no holding torque

    Carefully look at your dip switch settings. The legend of what is on and off is probably backwards of how it is normally described - also, check the dip switch to see which way is ON.

    I had a similar problem on drives that look like yours. The net result, I set the switch opposite of what they should be.

    Chris D

  6. #6
    Member
    Join Date
    Oct 2012
    Posts
    7

    Re: no holding torque

    i played some more tonight, and had some success, but would appreciate any additional thoughts...

    i found in the driver docs something about enable defaulting to on. i use grbl, so i set $4=1 to invert the enable. this did give me holding torque. i couldn't turn the shaft, but the stepper also would not run. i put $4 back to zero, and simply disconnected the enable wire from the driver. now the motor runs as it should and when it is still, i cannot make the shaft turn.

    i am pretty sure that i have the driver set to 2.7a, and "half current when stopped" turned on. both the driver and motor do not get the slightest bit warm to the touch. i am comfortable enough now with what is happening to leave bench testing mode and start moving the real machine. but i wish i understood what i have found a little better.

  7. #7

    Re: no holding torque

    Did you learn any more about this error?
    The 2 steppers I use for my Y axis have lost a lot of holding torque.
    The fault was intermittent for a while and now permanent.
    Nema 23 4Nm Bipolar Series
    Is it possible to measure the motor inputs with a multimeter and to check the motor is working OK?
    I don't want to just change from half to full current... could it do more harm? The steppers have run fine for years with no settings changed.
    Any tips appreciated.

  8. #8

    Re: no holding torque

    It was the grub screws on the pinon gears on both Y motor shafts. One was really loose and one was a bit loose!

    At least I got to spend ages checking motors and drivers.

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