When aligning two shafts using dial indicators, what is an important final step?

When aligning two shafts using dial indicators, what is an important final step?

• A. Ignore runout and rely on visual alignment.
• B. Tighten bolts to maximum torque before final check.
• C. Remove all shims and reattach indicators.
• D. Recheck alignment after tightening bolts to the specified sequence.

Answer: (D)

Final alignment after tightening is essential because clamping forces can shift the shafts. When you first set up with the dial indicators, you’re capturing the relative positions before the parts are clamped. Tightening the bolts in the specified sequence applies load gradually and evenly, which can cause small changes in position due to deformation, settling, or bearing preload. Rechecking after the bolts are torqued confirms the shafts still run true under the actual assembled conditions. If the readings drift beyond tolerance, you’ll typically adjust with shims or reposition until the final check again shows correct alignment, then re-torque and recheck. This final verification prevents hidden misalignment from turning into vibration, uneven wear, or premature failure in service. Other approaches, like ignoring runout or relying on visual alignment, or tightening to maximum torque before a final check, won’t guarantee the true assembled alignment and can lead to problems once the system is in operation.

Final alignment after tightening is essential because clamping forces can shift the shafts. When you first set up with the dial indicators, you’re capturing the relative positions before the parts are clamped. Tightening the bolts in the specified sequence applies load gradually and evenly, which can cause small changes in position due to deformation, settling, or bearing preload. Rechecking after the bolts are torqued confirms the shafts still run true under the actual assembled conditions.

If the readings drift beyond tolerance, you’ll typically adjust with shims or reposition until the final check again shows correct alignment, then re-torque and recheck. This final verification prevents hidden misalignment from turning into vibration, uneven wear, or premature failure in service.

Other approaches, like ignoring runout or relying on visual alignment, or tightening to maximum torque before a final check, won’t guarantee the true assembled alignment and can lead to problems once the system is in operation.