Exercise: Create a Spring using a Variable Section Sweep

1. Create two trajectory datum curves (typically sketched on a Datum Plane):
   Select Datum Curve icon > Sketch > Done.
2. Sketch the two line segments shown below.
     The 1st will become the Spine trajectory; 2nd becomes the "horizontal vector"

3. Create a "Helical" Surface feature:
   Feature > Create > Surface > New > Advanced > Done > Var Sec Swp > Done > NrmToOriginTraj > Done
4. Select the 1st Datum curve as the "spine" trajectory. Done
5. Select the 2nd Datum curve as the "horizontal vector". Done
6. Open Ends > Done
7. Close the References dialog box.
8. Sketch the profile: Draw a single straight line element from the "x" at the spine, at an angle to the horizontal plane.
9. Dimension it with a line length, and an angle.
   (Any other type of dimensioning scheme will likely cause it to fail part way through the first revolution)

10. Add the following Relation (use the "sdxx" number from the angle dimension):
    /*sdxx is the angle of rotation, and 12 is the number of turns, 20 is offset (opt)
    sd4 = trajpar * 360 * 12 + 20
11. Done > OK
    
12. Sweep a solid down the outer edge of the resulting surface feature.
13. Feature > Create > Solid > Protrusion > Sweep > *Solid > Done
    * Use Thin if the sweep is to be hollow
14. Choose Select Trajectory
15. Choose One by One, and select the edge of the helical surface.
16. Done > OK

17. Sketch the sweep's profile:

18. Done > OK
19. Put the Surface and the Curves on Layer(s) and Blank them.

Tips:

• The 2nd Datum Curve can be created as separate curves, or in the same sketch as the 1st Spine curve.
• If the Spine trajectory is "straight", you can use "Pivot Direction" in place of a 2nd trajectory curve.
• Instead of "burying" the number of turns as a constant in the section Relations; Before creating the feature, Set Up a Part Parameter called Turns, and use "turns" in the section Relation. Eg. sd2=trajpar*360*turns