What slave motor are you using. Even with a dull carbide cutter it should cut something. I only take .0005 at a time at 2 volts,which is half the distance between the lines on the scale of the wheel. Using the proper motor it should cut something even at 2 volts. Like the previous comment a high turn such as a 55 turn motor is the proper slave motor to use. Lots of torque!!!
A sharp tool bit is important, under a magnifying glass the tip of the cutting edge is rounded or chipped this will cut but leave a bad finish. One last thing,
make sure the motor is rotating in the right direction. Rotating into the flat side of the cutting edge!
Just my 2$
