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Patterns of Patterns

Can you make a pattern of patterned features?  It's really quite easy if you plan ahead.

This Tip-of-the-Month is a simple example of creating a pattern of a group of patterned holes.  The example is simple, but the technique can be extrapolated to create much more complicated patterns of patterned features.
 Figure 1
Hopefully you are familiar with feature patterns as we will not cover these in detail.  In general, the concept of patterning a pattern is to create the first feature pattern, group it then pattern the group.  Sound easy?  There's just one little trick required.

What's the Problem?

Create a feature (like the first hole in this example), dimensioned only from the sides of the block, then use the X and Y dimensions to pattern it in 2 directions as shown in Figure 1.  If you group the pattern and try to pattern it again using the X dimension, Pro/E will give you the error:

The Solution:  Plan for the patterned pattern.

One other control dimension is needed for our group to create the second pattern.  In this case we'll use a datum plane.  As shown in Figure 2, DTM1 is created at 0.50 from the block edge, then the hole is created at 1.00 from DTM1.

 Figure 2 Figure 3
Next, create the hole pattern as shown in Figure 1 using Feature > Pattern.  (This is a 2 directional pattern.  See Pro/E Help for more info.)
 Figure 4

Modify the dimensions of DTM1 and the first hole to make DTM1 go through the first hole as shown in Figure 3.  This gives the effect of having the dimension to DTM1 as the control dimension for hole 1 without being the incremental dimension for the pattern.  This is especially useful in creating the next pattern.

Create a Local Group for the Second Pattern:

The next step is to group the features required for the second pattern.  This is done by selecting Feature > Group > Create > Local Group > Enter a name - in this example the name is "Holes".  Next, pick the features for the group - this will be the pattern of holes and DTM1.  After selecting the features, complete the group using Done Sel > Done.

You now have a group called "Holes" which will also appear in your model tree.

Pattern the group:

The last step is to pattern the group.  Use Feature > Group > Pattern > then select your group.  Choose the dimension for DTM1 as the incremental dimension for the pattern, and you're on your way.

Figure 4 shows the result of the patterned group in the model tree.  Figure 5 shows the pattern of patterned features.  (Note that the patterns of holes actually overlap in the example to give the desired result.  The first set of holes is shown in green.)

 Figure 5
This technique is easily extrapolated to create much more complicated patterns of patterned features.  Enjoy.

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