Extending the Theoretical Line

When building the main surfaces, the transitions (fillets and transitional surfaces) are very useful tools for evaluating the shape of the main surfaces.

At this point in the tutorial, your model should resemble the image below, complete with fitted curves and a theoretical line.

In the above image, the spheres denote the end of the curves and help to visualize the area where the main surfaces will have to fit the scan lines. Because the length of the top surface does not match the length of the side surface, the theoretical line will have to be extended. Once the theoretical line has been extended, the side surface can be constructed. The side surface will be the first surface constructed because the theoretical line extends beyond the top surface.

To extend a curve

Open the file entitled Main Surface.wire.
Isolate the theoretical line (found in the “aw theo.line” layer).
Double-click the Object Edit > Extend tool to produce the option box.

Set Object Edit > Extend

options as follows.

Set this parameter...	To this value
Extend type	Extrapolate
Merge	off
Distance	0.000

Press the Go button at the bottom of the Object Edit > Extend tool’s option box.

NoteUse the options to select the end of the theoretical line and allow for movement to be executed by the left mouse button.

As shown below, curves can sometimes react to extensions in a different manner than intended.

To return the curve to its pre-extension form, enter a value of 0 in the Prompt line at the top of the screen.

TipExtend the theoretical line using the Control Panel > Evaluate > Move CV tool set to SLIDE. Using the Control Panel > Evaluate > Move CV tool will ensure that the curve will stay planar and that the shape will not be damaged.
Pick the first CV and slide the CV toward the rear of the model.
Continue with the rest of the CVs, but decrease the amount of sliding.