RioRandCNC TB6560 4 Axis 3.5A Stepper Motor Driver Board Controller Engraving Machine Powered by RioRand Advanced Technology Adjustable 1.5A-3A drive current settings for each axis - 25%,50%,75%,100% of full current can be set for different stepper motors Overload, over-current and over-temperature safety - Full protection for your computer and peripheral equipment;On board current switching - Power output can be set according to specific user requirement Relay spindle interface - Outputs Max. 36V 7.5A for spindle motors or coolant pump (only one device can be powered by this output!) Bipolar constant current chopper drive with non-resonant region - Controls motors smoothly through range without creep effect