### Performing a Linear Open Advanced Scan

Linear Open Scan dialog box

The Insert | Scan | Linear Open method will scan the surface along an open ended line. This procedure uses the starting and ending point for the line, and also includes a direction point for the calculation of the cut plane. The probe will always remain within the cut plane while doing the scan. There are three different types of LINEAROPEN direction techniques as explained in the "Direction Techniques area".

A Sample Linear Open Scan

To Create a Linear Open Scan

1. Ensure that you have a TTP or Analog probe enabled.

2. Place PC-DMIS into DCC mode.

3. Select Insert | Scan | Linear Open from the submenu. The Linear Open Scan dialog box appears.

4. Type the name of the scan in the ID box if you want to use a custom name.

5. Select the appropriate LINEAROPEN type from the Direction 1 Tech list.

6. Depending on your type of LINEAROPEN scan, type the appropriate increment and angle values into the available Max Incr, Min Incr, Max Angle, and Min Angle boxes.

7. If your scan traverses multiple surfaces, consider selecting surfaces by using the Select check box as discussed in the "Graphics Tab" topic.

8. Add the 1 point (starting point), the D point (direction to scan), and the 2 point (ending point), to the scan by following an appropriate procedure as discussed in the "Boundary Points area" topic.

9. Select the appropriate type of hits to take from the Hit Type list in the Hit Controls area.

10. Make any needed changes to the vectors in the Initial Vectors area. Do this by double-clicking on the vector, and making any changes to the Edit Scan Item dialog box, and then clicking OK to return to the Linear Open Scan dialog box.

11. Select the appropriate nominals mode from the Nominals list in the Nominals Method area.

12. In the Tolerance box in the Nominals Method area, type a tolerance value that at least compensates for the probe's radius.

13. Select the appropriate execution mode from the Execute list in the Exec Control area.

14. If you are using a thin part, type the part's thickness in the Thickness box in the Graphics tab.

15. If needed, select any of the check boxes from the areas in the Execution tab.

16. If using an analog probe, consider using the Control Points tab to run your scan optimally.

17. Click the Generate button in the Theoretical Path area, Path Definitions tab to generate a preview of the scan on the CAD model in the Graphics Display window. When you generate the scan, PC-DMIS will start the scan at the start point, and will follow the chosen direction until it reaches the end point.

18. If needed, you can delete individual points by selecting them one at a time from the Theoretical Path area and pressing the DELETE key.

19. If desired, use the Spline Path area in the same tab to fit the theoretical path to a spline path.

20. Make additional modification to your scan as needed.

21. Click the Create button. PC-DMIS inserts the scan into the Edit window.

To Create a Linear Open Scan on a 3D Wireframe CAD Model

To perform a Linear Open scan on a wireframe model, you should generally use a 3D wireframe CAD file. You need the 3D wires to define the shape of the feature you want to scan, as well as its "depth" (3D aspect). This type of scan follows the same procedure as above.

To Create a Linear Open Scan on a 2D Wireframe CAD Model

If you absolutely must perform a Linear Open scan on a 2D wireframe file, you can do so with some extra work.

1. Import the 2D CAD file. The CAD origin needs to be on the CAD some place and not off in body coordinates (this just makes things easier).

2. Select Insert | Feature | Construct | Line. The Construct Line dialog box appears.

3. Choose Alignment. This will construct a line at the CAD origin, normal to the surface of the 2D CAD data.

4. Access the Edit window and, if using millimeters for your units of measurement, change the length of the line from 1 (the default) to something longer, such as 5 or 10. For programs using inches, ignore this step.

5. Export the part program (the features only) to either an IGES or DXF file type and store the exported file to a directory of your choice.

6. Return to your part program and delete the Alignment Line that you created.

7. Import the file that you just exported back into the same part program. When prompted, click Merge to merge the CAD wire into your Graphics Display window. Your CAD model should now have a CAD wire normal to the rest of the other CAD wires.

8. Access the Linear Open Scan dialog box.

9. Click on the Graphics tab and then select the Select check box.

10. Click each wire that defines the feature to be scanned. Select them in the order that they will be scanned, starting with the wire where the scan will start.

11. Select the Depth check box.

12. Click on the imported wire that is normal to all the other wires.

13. Clear the Select check box. You can now select your 1, D, and 2 boundary points on the theoretical surface defined by the wires that define the surface's shape and the wire defining the depth.

14. If in online mode, select the Measure check box. Select FindNoms from the Nominals Method area. In the Tolerance box, select a good tolerance value.

15. Click Create. PC-DMIS inserts the scan, and if in online mode, begins the scan, finding the nominals.