Each time I home an axis, I get a very loud buzzing sound from the stepper motors with no motion, followed by very slow, "strained" motion. I've only gotten motion out of the Z-axis once. After that it's just been the loud buzzing. I've tried numerous combinations for current and speed settings, but nothing has had a significant impact or improvement. I'm wondering if the steppers do not have a high enough current rating and/or too high of an inductance for the drivers. Any thoughts or ideas would be much appreciated.

X and Y-axis steppers:
4.2 kg-cm NEMA 17 (# 42BYGH4807)

• Step angle: 1.8°

• Voltage ( V 8

• Current ( A 0.5

• Resistance (Ohms): 19

• Inductance (mH): 32

Z-axis:
2x 2.4 kg-cm NEMA 17 (# 42BYGH011)

• Step angle: 1.8°

• Voltage ( V 11.2

• Current ( A 0.33

• Resistance (Ohms): 34

• Inductance (mH): 48

Additional Printer Properties:

• Cartesian printer

• 12V Power Supply

• 8mm linear rails and M5 lead screws

• X-Carriage: E3D Titan Aero with pancake stepper and V6

• Y-Carriage: 6" x 6" x 1/2" MDF with aluminum build plate on top

If you're wondering why I chose these motors, I recently dismantled my Printrbot LC when the Printrboard died and tried to keep as many of the leftover, non-wood parts as I could when I rebuilt (the steppers being among them).