#### Sphere Calibration

1. Press the Probe soft key from the Main screen.

2. Press the Sphere Calibration soft key from the Probe screen to display the Sphere Calibration screen.

Parameters Definition:

- Tip Diameter (Probe/Nominal) - Provides the nominal diameter of the probe tip. The Measured value is updated when calibration completes.

- Diameter (Sphere) – Specifies the diameter of the Calibration/Qualification sphere.

- XYZ (Sphere/Center) - Specifies the center location of the qualification sphere in relation to the Work Offset location. This value should be 0,0,0 if the sphere was accurately positioned at the Work Offset.

- Feed Rate - Sets the speed in millimeters per minute (or inches per minute if in inch units) that the probe will travel during probe calibration.

- Prehit Distance - Specifies the distance from the theoretical hit location to which the probe will move before taking a hit. This is used during probe calibration. This is in millimeters or inches.

- Work Offset - Specifies the Work Offset at which the qualification sphere is located. Choose Machine to move relative to Machine coordinates.

Navigation Bar Soft Keys for this Screen:

| Find Center Selecting this soft key will cause the software to take sample hits to find the center of the sphere before measuring the sphere for calibration. |  |
| Click on the Forward button to access the Probe button. |  |
| View Calibration Report Select this soft key to view the available calibration report. |  |

Calibration Process:

1. Select the Work Offset to use for the calibration. The default is the Machine work offset.

2. Input the Diameter and Center Location for the Calibration/Qualification sphere. The user may identify the location center coordinates using the description at the bottom of this page.

3. Input the other parameters described above.

4. Jog the probe tip above the qualification sphere's center.

5. Click on the Execute soft key . NC Gage automatically takes 5 hits on the qualification sphere to determine the center of the sphere. After the center of the sphere is more accurately determined, NC Gage automatically takes 161 hits on the qualification sphere as defined by the Sphere Calibration parameters.

6. Once calibration has completed, the measured values are updated. You are now ready to measure features using your calibrated probe.

Locating XY:

- With Spindle Rotation - If the NC Machine supports spindle orientation (M19Sxxx), then the XY position of the sphere may be found with the Find Center apply function in the Calibration screen. This function rotates the spindle for each point so that runout of the probe tip is not a factor.

Locating Z:

- Insert a reference tool of known length into the spindle.

- With a feeler gage of known thickness, jog the tool down over the top of the sphere until the feeler gage has resistance when moving between the sphere and the tool. Use the smallest jog increment when close to the sphere.

- The sphere top surface Z is then equal to machine Z minus the feeler gage thickness minus the reference tool length.

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

- Read position of probe above top of sphere.

- Measure straight down, search distance is probe radius + 2* prehit distance.

- Set clearance plane height = Max of read point Z and prehit distance + probe radius above of contact point.

- Estimate center of sphere to be sphere radius below contact point.

- Set prehit radius = Sphere Radius + probe radius + prehit distance.

- Move to Clearance Plane.

- Move in Clearance Plane to a point that is prehit radius in +X direction from sphere center.

- Drop to height of estimated sphere equator.

- Measure equator with 16 points, extra moves between points if needed.

- Move up to next level (9 degrees above equator).

- Measure level with 16 points.

- Repeat process for all 10 levels.

- Measure point on top of sphere.

- Return to clearance plane.

Identify the Sphere Center Location

Locating XY:

- With Spindle Rotation - If the NC Machine supports spindle orientation (M19Sxxx), then the XY position of the sphere may be found with the Find Center apply function in the Calibration screen. This function rotates the spindle for each point so that runout of the probe tip is not a factor.

- With a Dial Indicator - Load a dial indicator in the spindle of the NC Machine and adjust it so that it is touching at the approximate equator of the calibration. Jog X and Y on the NC Machine so that when rotating the spindle the deviation on the indicator is minimized. The center of the sphere is the X and Y machine position.

Locating Z:

- Insert a reference tool of known length into the spindle.

- With a feeler gage of known thickness, jog the tool down over the top of the sphere until the feeler gage has resistance when moving between the sphere and the tool. Use the smallest jog increment when close to the sphere.

- The sphere Z is then equal to machine Z minus the feeler gage thickness minus the calibration sphere radius minus the reference tool length.

Notes:

- If a work offset is used for the center of the sphere, use the same work offset with a zero center location in NCGage.

- The Center Location X Y Z values in the work offset on the control are the coordinates of the nose point of the spindle if it could be positioned at the sphere center.