For a circular feature, the different Start
Angle and End Angle boxes define where
PC-DMIS probes the feature. For many situations, the default values are
sufficient, but there may be times when you need to measure a circular
feature that is partially obstructed by another feature or otherwise only
partially available for probing. Enter the start and end angles in a counter-clockwise
manner.
If you measure a hole with six hits and a Start Angle of 0 and an End Angle of 360, it looks something like this:
Notice that the Start Angle and the End Angle are the same: 0 and 360. Also, the six points making up the circle feature are equally distributed between the two angles. In this case, each point is taken at 60 degree intervals with the last point taken at 300 degrees.
However, if you change the Start Angle to 45 (purple arrow) and the End Angle to 270 (orange arrow), those values limit the hits to a certain portion of the circular feature:
Start and End Angle Boxes
Start Angle and End Angle boxes - These boxes let you change the default starting and ending angles on the feature. This is a user-supplied angle in decimal degrees. The starting and ending angles are relative to the values in the IJK Angle Vector boxes. If you rotate the view of the feature so that you look down its center, PC-DMIS will space the desired number of hits beginning at the Start Angle in a counterclockwise direction around the centerline until it reaches the End Angle.
These boxes are only available for Circle, Cylinder, Ellipse, Cone, and Sphere Auto features.
Start Angle 2 and End Angle 2 boxes - The Start Angle 2 and End Angle 2 boxes let you determine the secondary starting and ending angle on a sphere feature. This angle is in decimal degrees. The secondary angle, if looking at a side view of a sphere, starts at the sphere's equator and then moves towards the top pole as the angle increases to 90 degrees and then back down to the equator on the opposite side of the sphere at 180 degrees. These angles allow you to place the hits in an area where the probe can reach them without obstruction.
The Start Angle 2 and End Angle 2 boxes are only available for Sphere Auto features.
2 Degree Buffer Offset
When generating an arc using one of the circular auto features (Circle, Cylinder, Cone, Sphere, or Round Slot), PC-DMIS will offset the start and end angles each by two degrees. This way arcs retrieved from the CAD aren't probed on their starting and ending angles, possibly catching a corner. This shouldn't be an issue for the most part unless you are attempting to generate a small arc of only a few degrees. For example, if you want to generate a four degree arc of an Auto Circle, you will need to type in an eight degree arc parameter in the Start Angle and End Angle boxes, knowing that PC-DMIS will shorten the arc by two degrees on each angle.