Page 232 - Mastering SolidWorks

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SketchinG in 3D 203

Several relations are available in 3D sketches that are not found in 2D sketches, such as
AlongX, AlongY, AlongZ, and OnSurface.
As a general caution, keep in mind that solving sketches in 3D is more difficult than it is in
2D. You will see more situations where sketch relations fail or they flip in the wrong direction.
Angle dimensions in particular are notorious in 3D sketches for flipping direction if they change
and go across the 180-degree mark. When possible, it is advisable to work with fully defined
sketches and to be careful (and conservative) with sketch relations.

Using Planes in Space
It is possible to create planes directly in 3D sketches. These planes work like regular planes
initially. Having planes in the sketch also enables planar sketch entities such as arcs and circles in
3D sketches. Sketches can be created on these planes, and the sketch will move with the plane,
but the plane will also move with the sketch. Planes within 3D sketches can be confusing if you
expect them to work like 2D sketches and planes.
Figure 6.21 shows the PropertyManager interface for creating 3D planes.

Figure 6.21
The 3D Planes
PropertyManager

The confusing part is this: Say you create a vertical line on a plane in a 3D sketch. You can
then angle the line, and the plane will rotate with it. There is no way to rotate the plane on its
own unless you have some sketch geometry on the plane and cause that to rotate.
To open a sketch on a plane in a 3D sketch, double-click on the sketch or use the 3D Sketch on
Plane tool. The plane is activated when it displays a grid. You can double-click an empty space to
return to regular 3D Sketch mode. The main thing you give up with abandoning 3D sketch
planes is the simplification of certain sketch entities such as arcs and relations.
The advantage of using planes within a 3D sketch is that you abandon the parent/child
concept that you would otherwise embrace if you used a series of 2D sketches and 2D planes. In
my opinion, 3D sketches are an incredibly useful tool; however, the 3D planes concept is not very
well developed. I’m not ready to say it’s dangerous, but it certainly is not fully thought out.