Current Help System: PC-DMIS Portable (View Core Help)

### Creating "Single-Point" Measured Circle Features

Portable devices can create a measured circle feature by taking only one hit on that feature. This is termed a "single-point" circle. This is useful when attempting to measure a hole with a probe whose sphere size is larger than the hole's diameter and therefore cannot fit entirely into the hole to take the usual minimum three hits required. In this case, PC-DMIS creates the feature at the intersection of the workplane (or projection plane if a measured plane is currently active) and the probe sphere.

To create a single-point measured circle:

1. Select View | Other Windows | Quick Start to access the Quick Start interface. Single-point measured circles will not work using any other creation method.

2. From the Measure toolbar, select the Measure Single Point Circle toolbar item.

Measure Single Point Circle icon

3. Position the probe in the hole, and take a single hit. PC-DMIS enables the Finish button.

4. Click Finish. PC-DMIS creates the feature at the intersection of the workplane (or projection plane if a measured plane is currently active) and the probe sphere (see "How It Works" below).

Important: Remember that the calculation is done at the intersection of the probe tip with the workplane or projection plane. If the probe sphere is too high or too low, PC-DMIS will generate an error message indicating that the feature has failed. Also, be aware that measuring holes that are much smaller than the diameter of the probe will result in less accuracy in the resulting circle diameter.

How It Works:

Side view of the workplane and the probe sphere

A - Probe sphere

B - workplane

h - height of the sphere center to the workplane

R - radius of the measured circle

r - radius of the probe sphere

`R=sqrt(r^2 - h^2)`

Note: If the probe sphere is so high that r is less than h, the intersection math will fail and PC-DMIS will not solve the circle. If the sphere center is below the workplane (B), PC-DMIS will also not solve the circle.