Page 326 - Mastering SolidWorks

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298 CHAPTER 9 PAtterning And Mirroring

Figure 9.16
Using the Vary
Sketch option

On the Website

to better understand how this feature works, open the sample file called Chapter 9 Vary Sketch
.sldprt from the materials downloaded and edit Sketch2.
edit the 0.40-inch dimension. double-click it, and use the scroll arrow to increase the dimension;
watch the effect on the sketch. if a sketch does not react to changes properly, it cannot be used with
the Vary Sketch option. in this case, the 0.40-inch dimension is used as the direction, because that
is the dimension that will drive the sketch down the pattern. When using this option, the feature
sketch must be driven by a single dimension. if the 0.48-inch dimension were anchored to the origin
or the edge of the part like the 0.40-inch dimension, the pattern would not work properly. the direc-
tion dimension must be able to drive the sketch in the same way that this one does. these dimen-
sions cannot pass through the Zero value and cannot flip directions or move into negative values.
the whole operation is being driven by the construction lines and arcs at the centerline of the
slot. Sketch points along the model edges are kept at a certain distance from the ends of the slots
using the 0.50-inch dimensions. the arcs are controlled by an equal radius relation and a single
0.58-inch radius dimension. the straight lines at the ends of the slots are controlled by an equal
Length relation.
this type of dimensioning and relation creation is really what parametric design is all about. the
Vary Sketch option takes what is otherwise a static linear pattern and makes it react parametrically
in a way that would otherwise require lots of setup to create individual features. if you model every-
thing with the level of care that you need to put into a Vary Sketch Pattern feature sketch, then your
models will react very well to change.

Instances To Vary Instances To Vary is different from Instances To Skip and Vary Sketch. It
allows you to make various edits to the pattern. This is extremely powerful stuff for patterning.
Refer to Figure 9.17 to see the Instances To Vary PropertyManager panel of the Linear
Pattern feature.
Direction 1 Increments Direction 1 Increments controls the pattern spacing for the current
direction. So the first spacing is X, the second spacing is X + Y, then X + 2Y, and so on. Using
this option, the spacing between pattern instances can either grow or shrink, because the
increment can be positive or negative.
In the table below the Direction 1 Spacing Increments box, you can select additional dimen-
sions from the patterned feature to increment in the same way. In Figure 9.17, you see the
patterned feature gets further apart, narrower, taller, and moved to one side with each instance.