To use the Draft tool

1. Open the wire file First Surfaces.wire.
2. Pick the scan lines and use the View > Look At tool.
3. Make sure you are in the orthographic window and that the Perspective option is not checked.
4. Set all scan layers to Set State > Reference and isolate the top curve (middle portion) of the center line. You will find the curve in the “aw y CRV” layer.

   Using the selected curve in conjunction with the Surfaces > Draft Surfaces > Draft/Flange tool, you will be able to quickly create a surface. The Draft tool is a fast and easy way to create surfaces for defining the initial shape of the model. In general, surfaces should be used, instead of curves, to define the initial shape of a model. The surfaces constructed in this tutorial, created using the Draft tool, act as guides, or helpers, to produce the final, more professional surfaces.

5. Create a new layer called “Helper SRF”.
6. If the new layer is not highlighted in yellow, click the layer button until it changes to yellow.

   

   As long as the layer is highlighted in yellow, all new geometries will be assigned to that layer.

7. Double-click the Surfaces > Draft Surfaces > Draft/Flange tool to open the option box.
8. Select the top curve of the center line.
9. Press the Go button.
10. Adjust the manipulator until you produce a surface similar to the image below.
11. Choose Pick > Nothing .

    

The Surfaces > Draft Surfaces > Draft/Flange tool can create a flat surface from a curve, a surface edge, a curve-on-surface, or an isoparametric curve.

The draft surface consists of an angle, a length, and a direction – each of which is related to the current construction plane and can be manipulated in the Draft Surface Options box. Additionally, the Surfaces > Draft Surfaces > Draft/Flange tool produces a manipulator (a big cross) for changing the direction and angle of the surface. Another smaller manipulator is also produced that features a blue circle and a red flag at the end. The red flag changes the length of the draft while the blue circle changes the angle. Each manipulator allows values to be typed into the Prompt line at the top of the screen.

You can choose Flange by clicking the Draft button adjacent to the Construction Type option.

Flange is similar to Draft but the calculation of the direction is different. When a surface related object (an edge, a curve-on-surface, or an isoparametric curve) is selected, the normal of the surface is used to calculate the direction of the flange.

To use the cross-section tool

1. Select the draft surface, and activate the X cross-sections by clicking on the X 100.00 mm preset in the Cross Section portion of the Control Panel.

   

2. Adjust the spacing by double-clicking the X 100.00 mm preset to open the Cross Section Control option window.

   In the option window, there are three values for the Step option (X, Y, and Z). Make sure that the draft Step values equal the Step values for the scan line – for our model, the draft Step values should be set to 10.

   

To complete this section of the surface modeling process, create the next draft surface by choosing the edge of the previous draft. The new draft surface will have to follow the Z-direction.

Continue using the Draft tool to create a new surface

1. Create the next draft surface by picking the long edge of the completed draft surface. The new draft surface will be constructed in the Z-direction (pick the blue line on the big cross).
2. To fit the new draft surface to the scan lines, adjust the angle related to the Z-direction by using the blue circle on the small blue manipulator. The Angle option value in the option box will update based on the movement of the manipulator, or an Angle value can be entered manually into the option box.
3. Activate the Cross-Sections for the new draft surface as well. (If there is already a check mark in the X box in the Control Panel, you will need to turn it off then on again).