SolidWorks 2010 Bible

Part II: Building Intelligence into Your Parts

FIGURE 7.24

A projected curve using the Sketch On Faces option

Sketch On Sketch

This is the concept that most frequently causes difficulty for users. The Sketch Onto Sketch

Projected Curve option can be visualized in a few different ways.

Reverse 2D drawing visualization method

One way to visualize Sketch Onto Sketch projection is to think of it as being the reverse of a 2D

drawing. In a 2D drawing, 3D edges (you can think of the edges as curves) are projected onto

orthogonal planes to represent the edge from the Front or Top planes. The Sketch Onto Sketch

projection takes the two orthogonal views, placed on perpendicular planes, and projects them back

to make the 3D edge or curve. This is part of the attraction of the projected curve, because making

3D curves accurately is difficult if you do it directly by using a tool such as a 3D sketch spline;

however, if you know what the curve looks like from two different directions, then it becomes

easy. Figure 7.25 illustrates this visualization method.

When you think of describing a complex 3D curve in space, one of the first methods that usually

comes to mind is describing it as two 2D curves from perpendicular directions, exactly in the same

way as you would if you created projected drawing views from it. From this, it makes sense to see

the creation of the curve as the reverse process, drawing the 2D views first, from which you can

then create the 3D curve.

Intersecting surfaces visualization method

A second method used for visualizing Sketch On Sketch projected curves is the intersecting sur-

faces method. In this method, you can see the curve being created at the intersection of two sur-

faces that are created by extruding each of the sketches. This method is shown in Figure 7.26.