Many craftsmen and engineers have tried to balance a machine using a pencil to mark the shaft. Given a slow speed, large deflections, a steady hand and some nerve, this could have been successful (see Fig. 11-2). A weight is simply added opposite the point of shaft deflection or pencil mark on the shaft.
This article will present an accurate electronic approach to the pencil method of balancing. Electronically, an orbit path of the shaft can be generated. Also, electro-mechanically, a phase reference mark can be produced to show where the shaft is at a particular time. The author's experience is confined to machines with hydrodynamic bearings.
Fig. 11-2 - You can balance with a pencil if you have slow speeds, large deflections, and a steady hand.
Tip from The Practical Vibration Primer by Charles Jackson