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Using the Curve Driven Pattern

A Curve Driven Pattern does just what it sounds like: it drives a pattern along a curve. The curve could be a line, an arc, or a spline. It can be an edge, a 2D or 3D sketch, or even a real curve feature. An interesting thing about the Curve Driven Pattern is that it can have a Direction 2, and Direction 2 can be a curve. This pattern type is one of the most interesting and has many options.

For an entire sketch to be used as a curve, the sketch must not have any sharp corners — all the entities must be tangent. This could mean using sketch fillets or a fit spline. The example shown in Figure 9.16 was created using sketch fillets. This pattern uses the Equal Spacing option, which spaces the number of instances evenly around the curve. It also uses the Offset Curve option, which maintains the patterned feature's relationship to the curve throughout the pattern, as if an offset of the curve goes through the centroids of each patterned instance. The Align to Seed option is also used, which keeps all the pattern instances aligned in the same direction.

FIGURE 9.16

The Curve Driven Pattern using sketch fillets

Figure 9.17 shows the same part using the Transform Curve positioning option and Tangent to Curve alignment option.

Instead of an offset of the curve going through the centroids of each patterned feature instance, in the Transform Curve, the entire curve is moved rather than offset. On this particular part, this causes a messy pattern. The Tangent to Curve option gives every patterned instance the same orientation relative to the curve as the original.

The Face Normal option is used for a 3D pattern, as shown in Figure 9.18. Although this functionality seems a little obscure, it is useful if you need a 3D curve-driven pattern on a complex surface. If you are curious about this example, it is on the DVD with the filename Reference 3d Curve Driven.sldprt.

FIGURE 9.17

Using the Transform Curve and Tangent to Curve options

Using a Direction 2 for a Curve Driven Pattern creates a result similar to that in Figure 9.19. This is another situation that, although rare, is good to know about.

The rest of the Curve Driven Pattern works like the other pattern features that have already been demonstrated.

FIGURE 9.18

Using a 3D Curve Driven Pattern

FIGURE 9.19

Using Direction 2 with a Curve Driven Pattern

Using the Sketch Driven Pattern

Sketch Driven Patterns use a set of sketch points to drive the locations of features. The Hole Wizard drives the locations of multiple holes using sketch points in a similar way. However, the Sketch Driven Pattern does not create a 3D pattern in the same way that the Hole Wizard does. Figure 9.20 shows a pattern of several features that has been patterned using a Sketch Driven Pattern. A reference point is not necessary for the first feature.

FIGURE 9.20

Using a Sketch Driven Pattern

The Centroid option in the Reference Point section is fine for symmetrical and other easily definable shapes such as circles and rectangles, where you can find the centroid just by looking at it, but on more complex shapes, you may want to use the Selected Point option. The Selected Point option is shown in Figure 9.21.

FIGURE 9.21

Using the Selected Point option in a Sketch Driven Pattern

Using the Table Driven Pattern

A Table Driven Pattern drives a set of feature locations, most commonly holes, from a table. The table may be imported from any source with two columns of data (X and Y) that are separated by a space, tab, or comma. Extraneous data will cause the import to fail.

The X, Y Origin for the table is determined by a Coordinate System reference geometry feature. The XY plane of the Coordinate System is the plane to which the XY data in the table refers.

You can access the Coordinate System command by choosing Insert⇒Reference Geometry⇒Coordinate System from the menu. You can create the Coordinate System by selecting a combination of a vertex for the Origin and edges to align the axes. Like the Sketch Driven Pattern, this feature can use