3.1Nm holding torque tells you very little, it's like judging a car's performance by the quality of the hand brake.

Our American chums started this by buying motors purely on holding torque. "I've got Zillion ounce inch motors, the reeel McCoy! Incidentally, why can't I feed faster than 30 inches per minute?" :heehee:

What you want is a graph showing torque against steps per second for the voltage you plan to drive it with. It will be there somewhere, if it isn't, try somewhere else :tup: