Now we need to repeat the calculations for ALL the unbalance masses m_i (i = 1,2,3,…..) and find the resultant equivalent force in the balancing plane as shown in blue in Fig. 2.3.1. This resultant force is balanced out by placing a suitable balancing mass creating an equal and opposite force (shown in red). Since all the masses are rotating at the same speed along with the shaft, we can drop in our calculations – i.e., a rotor balanced at one speed will remain balanced at all speeds or in other words, our technique of balancing is independent of speed. We will review this towards the end of the lecture.

While these calculations can be done in any manner perceived to be convenient, a tabular form (see Table 2.3.1) is commonly employed to organize the computations. While doing this, it is also common practice to include the two balancing masses in the balancing planes as indicated in the table.

Table 2.3.1 Tabular form of organizing the computations for two-plane balancing technique