What is the position at which dial bar sag is applied for dial B?

The 12 o'clock position is where dial bar sag is applied for dial B because this position represents the point at which measurements are most typically taken when assessing the overall alignment and levelness of machinery parts or components. When dials are used in this manner, it allows for the most accurate readings as it is the topmost position, minimizing the effects of gravity and load imbalances on the measurement.

In mechanical contexts, using the 12 o'clock position for measurements is also a standardized practice, making it easier for operators and technicians to compare readings across different setups and equipment. This consistency ensures that assessments of sag or other variations can be easily interpreted and understood, which is essential for maintaining precision in alignment tasks.

Positions such as the 6 o'clock, 3 o'clock, and 9 o'clock are used for other measurements or checks but are not as widely adopted for determining dial bar sag specifically.