by dalewheat » Wed May 30, 2012 12:54 am
My Quantum's Z-axis driver keeps overheating. I'm using a RAMPS 1.2 (I think... it's not marked but it's not the 1.4, it's older) using a genuine Arduino Mega 2560 and 4 of the Pololu drivers.
I've adjusted the driver current down until the Z-axis just stops then bumped it up maybe 15-20%. It's really hard (for me) to accurately adjust the current limit on those things.
I'm using Marlin and Pronterface. When I run the Z-axis up or down, the little heatsink on the Z-axis driver jumps from near ambient temperature to over 70C in just a few seconds, then starts cutting out (as it should at that temperature). I've got it set to 16x microstepping because everyone else seems to be doing that. I have no idea why this is being done on this axis.
All the dimensions check out on all the axes. A 1mm move in any direction moves what looks like exactly 1mm. All the axes move in the correct direction, as well.
I've got both Z motors wired in parallel. I'm using an ATX power supply that's rated at 10A on the 12V line. Might it be better to wire them in series?
Ideas? Suggestions? Reminders? What am I doing wrong? I've already swapped drivers with the so-far-unused extruder driver, so I don't think it's a bad driver.
Thanks for any help!
Dale