I have a mill controlled by a PP  and a lathe controlled by a Smoothstepper.

All is well except that there is a distinct hissing noise that comes from both stepper motors on the lathe when there is no motion (idle condition).  The mill under idle conditions is silent.

The hissing noise changes pitch and intensity if I jog one of the axis slightly.

The hissing noise is not present if the smoothstepper is not powered up.

I am not worried about this but am curious if anyone else has noticed this?

Regards

Chrisjh

Presumably if the SS is not powered up then the motors will not be powered up, i.e. the drive is not getting any signals from the SS. In my experience noise from the steppers is related to the drive. Since you notice it when the motors are idle it may just be from the idle current reduction? What type of drive are you using?

my mill steppers hiss, I'm using a Routout stepper drive off two paralell ports. Doesn't seem to cause any harm.

Presumably if the SS is not powered up then the motors will not be powered up, i.e. the drive is not getting any signals from the SS. In my experience noise from the steppers is related to the drive. Since you notice it when the motors are idle it may just be from the idle current reduction? What type of drive are you using?

Thanks Jeff,

I am using Leadshine M542 drivers in the lathe and generic "no name" drivers in the mill.

I tried setting Idle current reduction "off" and it made no difference.  I think that you are right regarding the drivers causing the noise.  Presumably the PWM technique used is different from driver to driver.  Some seem to cause magneto striction effect which manifests itself as "hissing" in the steppers.

The good thing that came out of this was that when I was checking the settings of the mill drivers, I noticed that the "current reduction when Idle" switch was off.  I changed this setting on all 4 drivers for the mill and the steppers now run "just warm".

Regards

Chris