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

### Creating "Two-Point" Measured Slot Features

Similar to creating "Single-Point" measured circle features, portable devices can also create a measured square or round slot feature by taking only two hits, one on each end of the slot. This is termed a "two-point" slot. This is useful when attempting to measure a slot with a probe whose sphere size is larger than the slot's diameter and therefore cannot fit entirely into the slot to take the usual minimum number of hits required for a measured slot. 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 two-point measured slot feature:

1. Select View | Other Windows | Quick Start to access the Quick Start interface.

2. From the Measure toolbar, select either the Measure Two Point Round Slot toolbar item or the Measure Two Point Square Slot toolbar item.

Note: You don't have to use the Quick Start interface. If desired, you can instead simply click the desired slot feature from the standard Measured Features toolbar. However, this topic assumes that you are using the Quick Start interface.

3. Position the probe as far as it will go down into one of the ends of the slot, and take a hit. The hit should be on the bottom hemisphere of the probe sphere.

4. Position the probe as far as it will go down into the other end of the slot, and take a hit. The hit should be on the bottom hemisphere of the probe sphere.

- If the probe sphere properly intersected with the workplane (or projection plane) with both hits then PC-DMIS will enable the Finish button.

- If the first hit did not intersect properly with the workplane or projection plane, a message box will appear that says, "Hit 1 out of range". If the first hit did intersect with the work or reference plane, but the second did not, it will display, "Hit 2 out of range". If you receive one of these error message, you will need to retake both hits, adjusting your workplane or projection plane as needed so that a proper intersection with the probe sphere takes place.

5. 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).

- The width of the slot is based on the amount of probe sphere that intersects with the work or projection plane when the probe comes in contact with the feature on the part.

- The length of the slot is based on the distance between the two slot points.

Important: Remember that the calculation is done at the intersection of the probe sphere with the workplane or projection plane. If the probe sphere is too high (it doesn't intersect with the plane at all) or is too low (the hit is on the upper hemisphere or higher), PC-DMIS will generate an error message indicating that the feature has failed.

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 slot. The slot's width is twice this value.

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 slot. If the sphere center is below the workplane (B), PC-DMIS will also not solve the slot.