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

## Creating an Auto Cylinder

The Cylinder measurement option allows you to define a cylinder measurement. This measurement type is particularly useful when equal spacing of the hits is necessary for partial cylinders. The minimum number of hits needed to measure an Auto cylinder is six.

To access the Cylinder option, access the Auto Feature dialog box for a Cylinder (Insert | Feature | Auto | Cylinder).

Auto Feature dialog box - Cylinder

Note: Be aware that certain patterns of points (such as two rows of three equally spaced points or two rows of four equally spaced points) result in multiple ways to construct or measure a cylinder, and PC-DMIS's Best Fit algorithm may construct or measure the cylinder using an unexpected solution. For best results, measured or constructed cylinders should use a pattern of points that will eliminate unwanted solutions.
Also, when creating and measuring an auto cylinder be sure to consult the "Notes on Setting Cylinder Parameters Correctly" topic in the PC-DMIS Core documentation.

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

To generate a cylinder using surface data:

1. Click on the Surface Mode icon .

2. Position the cursor (outside or inside the desired cylinder).

3. Click once on a surface near the cylinder. PC-DMIS will highlight the selected cylinder. The dialog box will display the center point and diameter from the CAD data of the selected cylinder. It selects the end of the cylinder closest to where you clicked on the part model.

4. Define the length of the cylinder by defining the Starting Depth and the Ending Depth in the Contact Path Properties tab of the Probe Toolbox.

5. Make any other modifications to the dialog box and the Contact Path Properties tab of the Probe Toolbox as needed.

6. Click the Create button.

Creating by Using Surface Data with the CMM

To generate a cylinder using surface data with the CMM :

1. Take three hits in the hole or on the stud.

2. Move the probe to another depth

3. Take three additional hits. PC-DMIS will pierce the CAD surface closest to where the probe touched.

The displayed X, Y, Z values reflect the closest CAD cylinder, not the actual hits. The I, J, K reflects the surface normal vector. If a CAD cylinder is not found, PC-DMIS will display the closest point and ask that additional hits 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

Wire frame CAD data can also be used to generate a cylinder.

To generate the cylinder using wire frame data:

1. Click near the desired wire on the cylinder. PC-DMIS will highlight the selected wire and will select the end of the cylinder closest to where you clicked on the part model.

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 cylinder's center point and diameter once the wire has been indicated.

Note: If the underlying CAD element is not a cylinder, circle, or arc, 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 on the cylinder.

Creating without Using CAD Data

To generate the cylinder without the use of CAD data:

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

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

3. Take three additional hits on another level.

PC-DMIS calculates the sheet metal cylinder using all six hits. It is sometimes helpful to take a hit in between the two levels if PC-DMIS has difficulty in identifying the feature type. PC-DMIS will use the data from all of the measured hits until the Create button is selected. The X, Y, Z that is displayed is the calculated center of the cylinder (or stud).

Creating by Keying in the Data

This method allows you to key in the desired X, Y, Z, I, J, K values for the cylinder.

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.