How do I know if the spindle is spinning the right way?

Why are there two ways I can turn the “spindle on” knob?

The spindle should be turning clockwise for most milling operations. It thus may seem counterintuitive that there is both a forward and reverse switch to turn on the spindle. These correspond to whether the mill is in high gear or low gear. When the mill is in high gear, the spindle turns at high speeds, and you should set the dial to forward. When the mill is in low gear, the spindle spins at low speeds, and you should set the dial to reverse. If you do the opposite, the cutting tool will spin counter-clockwise and will not cut properly. You can tell which gear you are in by looking at the handle on the side of the mill. If it is facing toward you, it is in high gear. If it is facing away, it is in low gear. Do not turn on the spindle if the mill is in neutral (neither high nor low gear), and only change the speed of the spindle when the spindle is on.