Mechanical Engineering - Workshop Technology - Discussion

Anybody can explain the difference between basic shaft and basic hole?

In basic shaft, the hole is varied and th shaft is constant.

And in basic hole the shaft is varied and the hole is constant.

Absolutely right @Extrovert Annan.

In basic shaft, upper derivation is zero.
i.e .maxi.limit = basic size. &

In basic holes, lower derivation is zero.
i.e. mini.limit = basic size.

Thanks.

The correct answer is lower and upper deviations are zero.

A basic shaft is a shaft whose dimensions are defined such that its lower deviation (minimum limit) and upper deviation (maximum limit) are both zero. This means that the shaft's actual diameter is equal to its nominal diameter, with no tolerance or deviation allowed.

In other words, a basic shaft has a perfect, ideal diameter, with no variation or tolerance. This is a theoretical concept, as in practice, some deviation is always present due to manufacturing limitations.

The other options are incorrect because:
- Lower deviation is zero: This would mean that the shaft's diameter can be larger than the nominal diameter, but not smaller.
- Upper deviation is zero: This would mean that the shaft's diameter can be smaller than the nominal diameter, but not larger.
- None of these: This option is incorrect because the correct answer is indeed "lower and upper deviations are zero".