SolidWorks® Surfacing and Complex Shape Modeling Bible

Chapter 3. Sketching with Splines

IN THIS CHAPTER

• Why splines?

• Anatomy of a spline

• Controlling splines

• Fully defining spline sketches

• Tutorial

Splines are sketch entities that offer almost infinite possibilities to create shapes. They can imitate other sketch entities and at the same time give incredible flexibility with curvature, as well as curvature matching of other entities. Splines can match edges or complex curves either in 2D or in 3D. You can drive splines dimensionally by using better–behaved lines and arcs as reference geometry. When you are working with complex shapes, you must also work with splines.

A little history of the word "spline" may help you understand part of what it is all about. Dictionary.com defines spline as "a long, narrow, thin strip of wood, metal, etc.; slat." The origin of this word comes from the eighteenth–century shipbuilding trade. Think of the slats of wood used to create the outer skin of a wooden ship. Think of the way that these slats had to bend, and yet were held firmly in place at points, being nailed to the frame. (The word "loft" also comes from the shipbuilding trade, and is closely related to splines).

A second definition of spline from Dictionary.com is as follows: "a long, flexible strip of wood or the like, used in drawing curves." When designers drafted with a pencil, flexible lengths of wood or metal could be pinned down in various locations, and the shape occurring naturally due to the bending of the material would be traced by pencil. ...