For those who want to know more about choosing stepper motors, I've posted a resource information about "Micro stepping myths and realities" here http://www.openbuilds.com/resources/micro-stepping-myths-and-realities.158/ It also could give an explanation why the cheap TB6600 drivers give problems with missing steps and being erratic in operation. That problem might be solved by setting the micro steps at 1/4 or 1/8, hence giving the motors more torque and less chance of loosing steps. I tried yesterday evening my Buffalo at 1/4 micro stepping and Oh Dear! It's more loud than before but also nearly 4 times as strong! It also seems to work faster than at 1/16 settings. Didn't do any cutting yet and right now contemplating on setting it first to 1/8 to do some testing of heavy cutting. see how that goes.