## How do you find the hole in a position?

True position can be calculated using the following formula: true position = 2 x (dx^2 + dy^2)^1/2. In this equation, dx is the deviation between the measured x coordinate and the theoretical x coordinate, and dy is the deviation between the measured y coordinate and the theoretical y coordinate.

What is true position of a hole?

The true position is usually set at the centre of the feature being toleranced. For example, for a hole, the true position is set at the hole’s axis. Around it, we define the 2D or 3D diameter tolerance zone based on the feature characteristics.

### What is positional tolerance of hole?

The tolerance of position locates the holes within the pattern relative to each other. The large hole in the middle of the part is then located relative to the pattern of four holes. Therefore the large hole in the center does require a datum reference.

How holes shafts and fits are designated?

The standardized nomenclature of the shaft/hole fittings differentiates between hole basis and shaft basis fits. The fits are two digit letter/number designations where the hole basis fits are noted with a capital letter (H7) while the shaft basis fits are noted with a lower case letter (h7).

## What is the tolerance for the hole diameter?

ISO Hole Tolerances (ISO 286-2) (3mm-400mm):