[Smrtman5]

I belive conkbot is refering to large scale production machines, where the speed does need to be referenced. The knob, then is only used to tweak the speed Ie from %120 to %50 of the referenced speed. Anything more than a %10 change really should be edited in the program.
And dont forget about those infamous lefthanded drills. Or as was the case with the Bridgeport at school, if they hook the phases up in reverse. Then reverse comes in real handy lol.