#### Mode list

The Mode list in the Advanced Measurement Options area determines how the nominals will be computed for a given point. PC-DMIS allows you to choose between FIND NOMS, MASTER, NOMINALS, VECTOR, and SET NOM AX.

- If MODE = FIND NOMS is active, PC-DMIS pierces the CAD model to find the closest location on a CAD edge (or surface) to the measured point and sets the nominals to that location on the CAD element.

- If MODE = MASTER is active, PC-DMIS uses the measured feature as the nominal, but does not update the X, Y, Z and diameter data in the dialog box.

- If MODE = NOMINALS is active, PC-DMIS compares the measured feature with the theoretical data in the dialog box, using the measured data for calculations.

- If MODE = VECTOR is active, PC-DMIS uses your first three hits to calculate the appropriate vector to use for the feature. PC-DMIS does not adjust the location of the feature. You must take the hits with the Auto Features dialog box active.

- If MODE = SET NOM AX, PC-DMIS updates the nominal point location and the nominal approach direction before each execution.

For each of these modes see the more detailed description in the table below if more information is needed.

Note: If a nominal value is not known, simply select FIND NOMS from the list. While this option is active, every time a value is selected to be changed, PC-DMIS will prompt you to take the appropriate measurements on the part to obtain the values needed.

List Item | Description
Find Noms | When you select FIND NOMS from the Mode list, PC-DMIS will pierce the CAD model to find the closest location on a CAD edge (or surface) to the measured point, and set the nominals to that location on the CAD element. To find the nominals using CAD data:

1. Verify that PC-DMIS is set to Curve mode or Surface mode (available from the Graphics Modes toolbar), as is appropriate for the particular part program.

2. Click on the desired CAD element in the Graphics Display window. PC-DMIS will pierce the CAD element to obtain the location, but will not create a feature. Once the desired elements have been selected, PC-DMIS will automatically fill in the X, Y, Z and I, J, K values.

3. If the values are satisfactory, select the Create command button.

CAUTION: If you select the Measure box, PC-DMIS will measure the part.

If a hit is taken on the part while in FIND NOMS mode, PC-DMIS will search through the CAD elements and find the nominal CAD information that is closest to the measured point. If necessary, PC-DMIS will prompt you to take any additional hits on the part.

The next time the part is measured, PC-DMIS will set the nominal data to the nearest CAD element it can find. The mode switch will then be reset to NOMINALS.

Using Find Noms with Fixed Probes:

Faro or Romer arms using a fixed probe don't generate good approach vectors. Because of this, PC-DMIS cannot easily determine where to look for the surfaces.

To improve vectors from fixed probes:

1. Place the fixed probe on the part.

2. Press the Hit button.

3. Move the probe away from the part along the approximate surface vector.

4. Press the End button.

PC-DMIS will calculate and then use the vector between the hit and the probe tip's position.

Also, because the default vector from a Faro arm uses the axis of the fixed probe, the more you position the vector normal to the surface the more useful the vector is for Find Noms operations.

Master | If a point is created when the Mode list is set to MASTER, then the next time the part is measured, PC-DMIS will set the nominal data equal to the measured data. The Mode list will then be reset to NOMINALS.
Nominals | The NOMINALS option also requires you to have nominal data before the measurement process begins. PC-DMIS will compare the measured feature with the theoretical data in the dialog box, using the measured feature for any necessary calculations.
Vector | Note: This option is only available for Vector Point and Surface Point auto features. The VECTOR option allows you to update only the feature's vector during learn mode; it will not update the nominal XYZ values. This option helps you to set a feature's vector that you may not be able to obtain otherwise. With the dialog box open, take three hits on the feature. This will determine its vector.

You can use this mode as long as the dialog box remains open. Once you close the dialog box, the option is not available for the feature in the Edit window.

Supported Features: Vector Point, Surface Point, Corner Point, Line, Plane, Circle, Ellipse, Round Slot, Square Slot, Notch Slot, Polygon, Cylinder, Cone, Sphere

Set Nom Ax | Note: This option is only available for Vector Point and Surface Point auto features. The SET NOM AX option updates (or "sets") the nominal point location and the nominal approach direction before each execution. If you select an axis check box from the Location area, the CAD surfaces will be pierced along that axis. Otherwise, the update vector will be used.

The axis (or vector) selected tells PC-DMIS along which axis (or vector) the CAD surface will be pierced to find a new theo and target.

To select the SET NOM AX option:

1. Make sure the Show Extended Sheet Metal Option box is selected. See "Show Extended Sheet Metal Options" in the "Setting your Preferences" chapter.)

2. If desired, select one of the axis check boxes from the Location area.

3. Click SET NOM AX from the Mode list in the dialog box.

4. When you are done defining the rest of the auto feature, click the Create button. The FIND NOM AXIS will then be set to either the axis or the vector selected.

The Edit window for this reads: FIND NOM AXIS = TOG

TOG represents the axis or vector to which FIND NOM AXIS is set. Available options for TOG include:
XAXIS
YAXIS
ZAXIS
VEC
NONE

If you don't select any axis, then the result reads: FIND NOM AXIS = VEC by default.