Current Help System: PC-DMIS CMM (View Core Help)

## Creating an Auto Ellipse

The Ellipse auto feature option allows you to define an ellipse. The ellipse feature type works much like the sheet metal circle feature. It is particularly useful when the ellipse is positioned in a specific plane that is not parallel with any of the working planes. It is also useful if equally spaced hits are required for partial ellipses. The minimum number of hits required to measure an ellipse is five.

To access the Ellipse option, access the Auto Feature dialog box for an Ellipse (Insert | Feature | Auto | Ellipse).

Auto Feature dialog box - Ellipse

With the dialog box open, depending on your situation, use one of these methods to create the feature:

Creating by Using Surface Data on the Screen

1. Click the Surface Mode icon .

2. Using your mouse, click once on the ellipse displayed in the Graphics Display window. PC-DMIS will compute the necessary X, Y, Z and I, J, K data.

3. Make any other modifications to the dialog box as needed.

4. Click Create.

Creating by Using Surface Data with the CMM

To generate an ellipse measurement using surface data with the CMM, take a minimum of five hits on the ellipse. PC-DMIS will pierce the CAD surface closest to where the probe touched. The displayed X, Y, Z values reflect the closest CAD ellipse, not the actual hits. The I, J, K reflects the surface normal vector. If a CAD ellipse is not found, PC-DMIS will display the closest point and ask that additional points be taken.

The Find Noms option should be selected from the Mode list for this measurement method. See the "Mode List" topic in the PC-DMIS Core documentation for additional information on nominals.

Creating by Using Wire Frame Data on the Screen

1. Click near the desired wire on the ellipse. PC-DMIS will highlight the selected wire.

2. Verify that the correct feature has been selected. The probe approach is always perpendicular to the feature, as well as perpendicular to the current probe centerline vector. The dialog box will display the value of the selected ellipse's center point and diameter once the wire has been indicated.

3. Make any other modifications to the dialog box and the Probe Toolbox as needed.

4. Click Create.

Note: If the underlying CAD element is not an ellipse, additional clicks may be necessary to identify the feature. If PC-DMIS doesn't highlight the correct feature, try clicking on at least two additional locations of the ellipse.

Creating without Using CAD Data

If the ellipse is to be generated without the use of CAD data:

1. Take three hits on the surface to find the plane that the ellipse is lying in.

2. Take five additional hits in the hole (or on the stud).

PC-DMIS will use the data to calculate the sheet metal ellipse. Additional hits can be taken until the Create button is clicked. The X, Y, Z that is displayed is the calculated center of the ellipse. Also shown are the calculated major and minor diameters, along with the orientation vector.

Creating by Keying in the Data

This method allows you to key in the desired X, Y, Z, I, J, K values for the ellipse. In addition, the major and minor diameters of the ellipse as well as the angle vector I2, J2, K2 may also be keyed in.

1. Type in the desired X, Y, Z, I, J, K values for the feature into the dialog box.

2. Click Create to insert the feature into your part program.

See the "Mode List" topic in the PC-DMIS Core documentation for additional information on nominals.