### Circle (Boss)

To create a Circle Boss command:

1. Press the Measure soft key from the Main screen's Navigation Bar.

2. Press the Circle (Boss) soft key to display the Measure Circle (Boss) screen.

3. Follow the instructions on the screen to insert the command.

Parameters Definition:

- Nominal (XYZD Nominal) - Defines the nominal position of the cylinder.

- Prehit Distance - Defines the distance away from the nominal surface at which the probe will start seeking the surface during measure.

Properties Definition:

- Number of Points - Defines the number of points that will be probed for the cylinder during execution (not learn mode).

- Start Angle - Defines the starting point for a section of the circle to measure. Rotation starts at 0 along the primary axis and grows such that 90 is at the secondary axis. The primary axis is X in the XY work face, Y in the YZ work face, and Z in the ZX work face. The secondary axis is Y in the XY work face, Z in the YZ work face, and X in the ZX work face.

- End Angle - Defines the end of the section of the circle that will be measured. The start and end angle will only be used when the featured is measured in execute mode. Learn mode will automatically take hits in opposing primary and secondary axes directions. If the circle does not continue around for 360 degrees, then Learn Using Values on Screen could be used to enter the nominal location with a proper start and end angle defined. Then, with Learn then Measure selected, NC Gage will measure the feature.

Note: The number of rows and points per row will be equally spaced along the defined circle.

Optional Settings:

- Hit Clearance Plane - Selecting this option causes the probe to move to a clearance plane between each hit of the feature. The edit box to the right will allow the user to enter the distance to the plane. This plane is not the program clearance plane.

- Learn Then Measure - Selecting this option causes the machine to learn the location of the part using default parameters and then immediately re-measure the feature with the properties as set on the screen. This will allow the user to test all the set parameters and should warrant a more accurate and reliable first article inspection.

- Learn Using Values on Screen - This allows the user to enter the nominal values of the feature and have the software measure at that location.

Available Navigation Bar Soft Keys on this Screen:

Learn Process:

1. Position the probe near the surface on the side of the boss and press the Read Position soft key . This will be the height location for all the hits. Press the Return to Previous Step soft key to cancel this measure position.

2. Position the probe above the center of the boss and press the Read Position soft key . This will be used to determine the center of the boss. Press the Return to Previous Step soft key to cancel this measure position.

3. Position the probe for automatic measurement, and press the Learning and Creating a Command soft key . NC Gage takes one hit below this position to determine the height of the boss. It then automatically takes hits in a similar fashion as depicted below.

Image indicating the manual positions to jog the probe to (A-B) and the automatic probing pathways (red lines) taken by NC Gage as it measures four points (positions 1-4)

4. Once the feature has been measured, the measured values are updated. Press the Confirm and Append Current Command to End soft key . The feature command is added to the part program. Press the Return soft key to return to the previous screen without saving.

The following is the specific feature path and logic built into NC Gage:

Learn Boss Feature Path

- Read position of probe next to side of boss, Z value will be measurement height.

- Read position of probe above center of boss, XY values define center, Z value is safe height.

- prehit radius = projected 2D distance between two read position points.

- Move to safe height.

- Move at safe height to a point above prehit point 1, which is prehit radius from center in +X.

- Drop to measurement height.

- Measure point, target is center at measurement height.

- Move to safe height.

- Move at safe height to a point above prehit point 2, which is prehit radius from center in -X.

- Drop to measurement height.

- Measure point, target is center at measurement height.

- Move to safe height.

- Move at safe height to a point above prehit point 3, which is prehit radius from center in +Y.

- Drop to measurement height.

- Measure point, target is center at measurement height.

- Move to safe height.

- Move at safe height to a point above prehit point 4, which is prehit radius from center in -Y.

- Drop to measurement height.

- Measure point, target is center at measurement height.

- Move to safe height.

Execute Boss Feature Path

- Define prehit radius = Boss Radius + prehit distance + probe radius.

- Define target radius = Boss Radius - prehit distance – probe radius, if this is < 0, set to 0.

- If current position is lower than the clearance plane height then move up to clearance plane.

- Move to position above first prehit point. This point is a distance of prehit radius from boss center in the direction of the start angle.

- Drop down to the measurement level.

- Measure point, target is target radius from boss center along angle.

- Retract and move to prehit of next point. If needed use one or more smaller moves to avoid contact with the boss.

- Measure point, target is target radius from boss center along angle.

- Continue from start angle to end angle measuring specified number of points.

- If local clearance plane is enabled move to the local clearance plane between each point to get to next prehit point.

- After last point is measured, the probe moves up to the clearance plane height.