>I understand WHY unbalance causes vibration. What I don't understand is how >a Tachometer helps you to determine the degree of imbalance. The tach isn't used for balancing, it's used to measure performance. Slightly related, but as a measurement of increase, not to balance per se. >I'm not convinced that strobing will make the wobbling rate seem slower to >the eye. Yes, it does. Actually, the strobe light is to be run either off a pot or by watching the rotation of the propeller, under user selection. Andy ================================================================== Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA ==================================================================