motors Humming and growling sometimes

[artform]

Hi, I am very new to all this xylotex stuff.
I have set up an X2 mill a Xylotex ver 4.00 4 axis
I have Step Syn motors 1.8A, I have wired them unipolar
I have set my vref's to 2.59 volts
I am getting jog control from mach 3 on all 3 axis
Problem - sometimes the motors when they stop sit there humming and making growling noises, it seems when I am jogging, all is ok, when i stop, motors are not happy. As i said, sometimes.

I have no idea what could be the problem. please help.

would it be because i have them wired unipolar ?

Thanks to anyone who might help

[Oldmanandhistoy]

Hi,

Not sure how you have your motors wired but you do not have the option of wiring them unipolar.

Check this link out for motor wiring options and wire them bipolar parralel or bipolar series. http://www.wimb.net/index.php?s=motion&page=52

John

[artform]

Thanks old man, that fixed it running perfect now.