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Creating Rectangular Patterns

You may need to duplicate the whole geometry of one or more features and to position this geometry on a part. Patterns let you do so, and by the way accelerate the creation process.The application allows you to define three types of patterns:

This document deals with the following:

You can also find information about patterns and updates by reading Optimizing Part Design Application, Patterns.

This task shows you how to duplicate the geometry of one pocket right away at the location of your choice using a rectangular pattern. Then, you will learn how to modify the location of the initial feature.
Open the RectangularPattern.CATPart document.
  1. Select the feature you wish to copy, that is the pocket as shown:

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  2. Click the Rectangular Pattern icon w.2.
    The Rectangular Pattern Definition dialog box that appears displays the name of the geometry to pattern.
    If you click the Rectangular Pattern icon w.2 prior to selecting any geometry, by default, the object to be patterned is the current solid. For more information, refer to Patterning Current Solids.

    w.3
    If you change your mind and decide to pattern the current solid, click the Object field and use the Get current solid contextual command.
    Each tab is dedicated to a direction you will use to define the location of the duplicated feature. In this task, you will first set your specifications for the first direction
    .

Reference Direction

  1. Click the Reference element field and select the edge as shown below to specify the first direction of creation.
    An arrow is displayed on the pad. If needed, click the Reverse button or click the arrow to modify the direction.

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  • To define a direction, you can select an edge or a planar face.
  • Contextual commands creating the reference elements you need are available from the Reference element field:
    • Create Line: For more information, see Creating Lines.
    • X Axis: the X axis of the current coordinate system origin (0,0,0) becomes the direction.
    • Y Axis: the Y axis of the current coordinate system origin (0,0,0) becomes the direction.
    • Z Axis: the Z axis of the current coordinate system origin (0,0,0) becomes the direction.
    • Create Plane: see Creating Planes.

    If you create any of these elements, the application then displays the corresponding icon next to the Reference element field. Clicking this icon enables you to edit the element.

  1. Let the Instances & Spacing options to define the parameters you wish to specify.
    The parameters you can choose are:

    • Instances & Length
    • Instances & Spacing
    • Spacing & Length
    • Instances & Unequal Spacing: distinct spacings can be assigned between instances.
    Choosing Instances & Spacing dims the Length field because the application no longer needs this specification to space the instances.
If you set Instances & Length or Spacing & Length parameters, note that you cannot define the length by using formulas.
  1. Enter 3 as the number of instances you wish to obtain in the first direction.

Deleting the instances of your choice is possible when creating the pattern. In the pattern preview, just select the points materializing instances. Conversely, selecting these points again will make the application create the corresponding instances.
  1. Define the spacing along the grid: enter 14 mm.

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Defining the spacing along the grid and length of your choice would make the application compute the number of possible instances and space them at equal distances.
  1. Now, click the Second Direction tab to define other parameters.
    Note that defining a second direction is not compulsory. Creating a rectangular defining only one direction is possible.
  2. Click the Reference element field and select the edge to the left to define the second direction.
    If necessary, click Reverse to make the arrow point in the opposite direction.
  3. Let the Instances & Spacing option: enter 3 and 10 mm in the appropriate fields.

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  4. Click Preview to make sure the pattern meets your needs.
    Additional pockets will be aligned along this second direction.

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  5. Click OK to repeat the pocket’s geometry nine times.
    This is the resulting pattern. RectPattern.1 feature is displayed in the specification tree.

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  6. Let’s now edit the pattern to make it more complex: double-click the pattern to display the dialog box.
  7. Click the More button to display the whole dialog box.
    The options available let you position the pattern.

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  1. To modify the position of the pockets, enter 5 degrees as the rotation angle value.
  2. Click Preview.
    You can notice that all pockets have moved slightly:

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  3. Now, modify the location of the initial pocket. To do so, enter 2 in the Row in Direction 1 field.
    The application previews how the pattern will be moved. It will be moved along the direction as indicated:

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  4. Finally, enter 2 in the Row in Direction 2 field.
    The application previews how the pattern will be moved. It will be moved along these two directions defined in steps 17 and 18:

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The Simplified representation option lightens the pattern’s geometry. What you need to do is just check the option and double-click the instances you do not want to see. The instances are then represented in dashed lines during the pattern definition and then are no longer visible after validating the pattern creation.When the Simplified representation option is on, because the pattern’s geometry representation is modified, the part mass is modified too.

This option is particularly used for patterns including a large number of instances.

  1. Click OK.
    The application has changed the location of all pockets. Only four of them remain on the pad.

    w.13

Instances and Unequal Spacing

You can assign specific spacing values between each instance by proceeding as follows:

  1. Create a new pattern for the purpose of this task: select Pocket.1 as the object to pattern, and first set the Instances & Length parameter using the length values as shown here:

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  2. Set the Instances & Unequal Spacing parameter for the first direction.
    Spacing values are displayed between each instance.
  3. To edit the values between each instance, you need to edit values individually. First, select the spacing of interest if not already done.
  4. Then, choose one of the methods described hereafter: For example, if you wish to change 10mm for 17mm for the selected spacing, you can:
    • double-click the length value in the geometry area. This displays the Parameter Definition dialog box in which you can enter the new value.
    • directly enter the new value in the Spacing field of the Rectangular Pattern Definition dialog box.
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  5. Repeat the operation for the other spacings.
  6. Click OK when done.

Removing Instances

Remember that clicking an instance once removes the instance from the specifications. Clicking once or double-clicking an instance does not lead to the same result then.

It is possible to create Cartesian patterns with variable steps. To do so, you need to define formulas. For more information, refer to Knowledge Advisor User’s Guide Version 5.
  • During your design, you may need to rework instances specifically. You will then have to use the Explode contextual command to delete your pattern while keeping geometry. For more information, refer to Exploding Patterns.

Complex Patterns

You can pattern a list of Part Design features by proceeding as follows:

  1. Multi-select the features to be duplicated.
    These features must belong to the same body.
  2. Click the Rectangular Pattern icon .
    The features are indicated in the Object field.

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  3. Set the parameters you need as shown in the task above.
    These rules are to be kept in mind before patterning a list of features.

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The pattern does not give appropriate results if the list of features to be patterned contains elements with non-movable sub-elements (wireframe geometry like Point, Line, Plane or B-Reps like Edge, Face etc.). In this case following warning message is displayed:

The list of features to be patterned contains elements with non-movable sub-elements (i.e. wireframe geometry, edges etc.). Consequently, the Pattern operation may produce wrong results. (In case you want to pattern a User Feature, launch pattern command first and then select the User Feature for stable results.) Do you want to continue?

Editing a List of Features

Editing a list of features consists in adding or removing features from the list. To do so, you just have to click the Object field and select the feature of interest to add it or remove it from the list.

Note however that adding a feature to a pattern is possible only if your pattern is already based on a feature list. In other words, you cannot add any feature to a basic pattern created using a single feature.

Patterning Current Solids

A current solid is composed of one or more features belonging to the same body. It is the result of the operations as mentioned in the specification tree, the last operation being the current one. For more about current features, see Scanning a part and defining local objects.

To pattern a current solid, just click the Rectangular Pattern icon w.2. There is no need to select any geometry. By default, the object to pattern is the current solid. You then just have to enter your specifications in the dialog box.

Note that if you change your mind and decide to pattern a feature, you just have to click the Object field and select the feature of your choice.

In the following example, the current solid is the result of one pad and one hole.

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The instances created via the Pattern command are composed of pads and holes only.
You cannot transform a patterned list of features into a patterned current solid and vice-versa.

Patterning User Defined Features (UDFs)

There are two ways of patterning a User Defined Feature. The order of selection affects the availability of the Keep specifications option:

Method 1

  1. Click Rectangular Pattern .
  2. Select the user defined feature (UDF) you want to duplicate.
    Here the pattern is treated as a single feature. Keep specifications is disabled and dimmed.

About Color Propagation

When using this first creation method, the Pattern command does not propagate the UDF’s color to the pattern.

Method 2

  1. Select the user-defined feature UDF you want to duplicate.
  2. Click Rectangular Pattern .
    The application treats the pattern feature as a complex pattern, that is a pattern made from a list of diverse features. Keep specifications is enabled and dimmed. The created pattern you create keeps the UDF specifications.
  • You can only pattern UDF solids composed of one single feature.
  • Patterning UDFs is allowed in Part Design, not in Generative Shape Design.
  • Selecting the pattern capability then the UDF is the method we recommend for best performance optimization.
  • If the UDF contains elements with non-movable sub-elements (wireframe geometry like Point, Line, Plane or B-Reps like Edge, Face etc.), the pattern may produce wrong results. In this case, a warning message as described in the Complex Patterns section is displayed.

About Color Propagation

When using this second creation method, the Pattern command instantiates the UDF directly and this UDF instance is directly used to build the result of the UDF. Therefore the pattern obtained can inherit the UDFs’ color.

Patterning Bodies

The application patterns the body’s geometry without taking into account the body’s polarity. However, if then you insert the pattern obtained in another body, then the application takes the polarity of this body into account. This explains why patterned bodies are not visible if they are inserted in negative bodies.

In the following example, the user pattern points to Body.2 included in Body.3 which is a positive body. In this case, the pattern is visible in the geometry area because the pattern’s result is added to existing geometry.

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If Body.3 is changed into a negative body (the Add feature was changed into a Remove feature), then the user pattern is no longer visible because the pattern’s result is subtracted from existing geometry.

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Keep Specifications

Selecting the Keep specifications option creates instances with the limit Up to Next ( Up to Last, Up to Plane or Up to Surface) defined for the original feature. In the example below, the limit defined for the pad, i.e. the Up to surface limit, applies to all instances. As the limiting surface is not planar, the instances have different lengths.

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In our scenario above, as the pocket’s height is specified, activating the Keep specifications option is meaningless.The Keep specifications option is not available if you are patterning a pattern.

In case you create a pocket and a hole that are overlapping each other and pattern it by selecting the hole as the Object to Pattern:

  • Selecting the Keep specifications option creates the pattern as shown:
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  • Clearing the Keep specifications option creates the pattern as shown:
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In case you have created two overlapping pockets and pattern the pocket, you get the complete circular profile that is independent of the Keep specifications option.

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