How much should you tighten the bearing nut on the wrist pivot shaft?

The correct answer emphasizes the importance of achieving a specific starting force for the bearing nut on the wrist pivot shaft, which is measured in kilogram-force (kgf). Setting the starting force within the range of 1.8 kgf to 2.2 kgf ensures that the bearing nut is neither too loose, which could lead to excessive play and inefficiency, nor too tight, which could cause undue strain or damage to the components.

This specified starting force allows for optimal performance of the wrist pivot shaft, as it is crucial for the precision and responsiveness of the machine's movements. Adequate torque ensures proper alignment and functionality of the bearings over time, promoting longevity and reliability of the mechanical assembly.

Other options either suggest insufficient fastening methods or do not provide the necessary precision required for mechanical components subjected to operational stresses. For example, tightening until resistance is felt may lead to inconsistent and variable results, while merely hand-tightening does not offer the necessary security or accuracy. Similarly, using a torque wrench at a specific value without considering the recommended range could prevent achieving the desired balance between tightness and freedom of movement.