A video describing how to correctly use and read a dial indicator during shaft alignment. This includes total indicator reading, the validity rule, and true position sensing. These concepts are very useful for easy alignment of a shaft during machining processes.

Shaft alignment is an important step in connecting an engine or turbine to a pump. Shaft alignment must be performed in order to prevent considerable wear or premature breakdowns of these machines.

Using a dial indicator is fairly simple; however there are certain concepts that are critical to properly reading the indicator, or simply for reading the indicator more easily. First, total indicator reading. The TIR is what a dial indicator will read initially as the offset between two shafts at any given point. The actual vertical offset of the shafts is half the TIR. TIR indicates the vertical offset on both sides of the shaft combined. After halving the TIR indicated, the dial indicator will display true position.

Finally, the validity rule implies that the reading taken from the top and bottom of the shaft combined must equal the reading from the sides of the shaft combined. This allows to