the maximum motor temperature quoted varies from one manufacturer to another but is usually 70 to 80 C !
on this data sheet its 80C
http://docs-europe.eambelectrocompon...6b808f8981.pdf the manufacture will expect the metal work of the machine to act as a heatsink for the motor
if its of all wood construction you may have to reduce the current or add a fan !
unlike servo motors were the motor current depends on the mechanical load
the stepper motor current is always the maximum set by the controller
unless its like the G540 and reduces the current to 70% when idle
John