What is the best method of alignment to apply when shafts cannot be axially secured?

Cross dialing is the most effective method of alignment to use when shafts cannot be axially secured because it provides an accurate way to determine the angular and parallel alignment of rotating shafts. This technique involves measuring the misalignment using dial indicators, which can effectively capture slight variations in alignment that may occur due to operational conditions or thermal expansion.

Cross dialing is particularly useful in situations where you can't physically secure the shafts in a fixed position; it allows for adjustments while the machinery is in its operating position. The method records the position of the shafts at different points, helping to identify any misalignment that exists. This is critical for ensuring that machines function efficiently and with minimal vibration, which can lead to increased wear and tear.

Other methods like laser alignment, while highly accurate, may not always be feasible in situations where secure positioning isn't possible. Bubble level alignment provides a more general measure and can be less precise, making it unsuitable for shafts requiring high accuracy. Eye alignment relies on visual inspection, which is not sufficient for the precision required in many industrial applications, as it can lead to subjective assessments rather than precise measurements.