#### Use Thickness

The Use Thickness icon displays a T list (T for "thickness") and a box where you can type the part thickness value.

When measuring the side of the part that is modeled in PC-DMIS, the part thickness value should be set to zero. The part thickness option should only be used when measuring the side of the part that is not drawn in the CAD data. | Defining a thickness amount is primarily used for thin parts (plastic or sheet metal) where the CAD data only describes one side and you want to measure the other side. Often with thin parts, the CAD engineer will only draw one side of the part, and then specify the material thickness. PC-DMIS will apply this material thickness automatically when using the CAD surface data.

Positive or negative values can be used. This thickness will be applied automatically along the surface normal vector each time CAD data is selected. If the feature has more than one normal vector (i.e. angle points and corner points), the thickness will be applied along the first normal vector.

The Edit window command line for this option would read:

THEO_THICKNESS = n

or

ACTL_THICKNESS = n

n: a numerical value indicating the thickness of the part.

From the T list, select Theo, and in the box below the T list, type the thickness value when the theoretical values need to be adjusted by a thickness because measurements are being done on opposite side of material.

From the T list, select Actual, and in the box below the T list, type the thickness value when measurements are being adjusted by the thickness back to the original theoretical XYZ locations. With this option it will appear that the theoretical and measured values have not been offset and the target is offset. You still need to modify your target so that PC-DMIS drives to the correct location.

Select the None option if you don't need to apply thickness. For most machines, a thickness of 0 or selecting None has the same effect. For portable arm machines, however, selecting None and specifying a value actually applies the thickness to a shank style measurement. In this type of measurement, you use the cylindrical shank of the probe to measure instead of the probe tip. To do this you need to first define sample hits. PC-DMIS can then determine the location of the supported feature (Circles, Ellipses, Slots, and Notches) using the shank.

Note: When switching between theoretical and actual thickness, the measurement location will not change. When using theoretical thickness, PC-DMIS modifies the theoretical, measured, and target locations to include the (theoretical) thickness. When using actual thickness, PC-DMIS modifies only the target location by adding the (actual) thickness value to the original theoretical location. Later, after feature measurement, PC-DMIS subtracts the (actual) thickness from the measured value. Both methods yield the same measurement location. It is simply how PC-DMIS reports the feature's theoretical, actual, and target values that changes.