What is shaft basis and hole basis system?

Question

Accepted Answer

Shaft basis and hole basis are two systems used to determine the tolerance limits of mating parts in mechanical design.

Shaft basis system: The shaft is kept constant and the hole is varied to achieve the desired fit.
Hole basis system: The hole is kept constant and the shaft is varied to achieve the desired fit.
The system chosen depends on the application and the desired level of clearance or interference between the mating parts.
Examples of applications include bearings, gears, and couplings.
Shaft basis system is commonly used in high-speed rotating machinery to ensure proper alignment and reduce vibration.
Hole basis system is commonly used in press fits to ensure a tight and secure connection between the mating parts.

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