Creating Circular Patterns

The application allows you to define three types of patterns:

This task shows you how to duplicate geometry of one or more features right away at the location of your choice using a circular pattern.

This document also deals with:

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

Make sure the item you wish to duplicate is correctly located in relation to the circular rotation axis.

Open the CircularPattern.CATPart document.

  1. Select the pad whose geometry you wish to copy.

  2. Click Circular Pattern .
    The Circular Pattern Definition dialog box is displayed and the feature's name appears in the Object field.
    If you change your mind and decide to pattern the current solid, click the Object field and use the Get current solid contextual menu item. For more information, refer to Patterning  Current Solids

Keeping Specifications

Checking 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. The example below shows you that the limit defined for the pad, that is the Up to surface limit, applies to all instances. As the limiting surface is not planar, the instances have different lengths.


The Parameters field lets you choose the type of parameters you wish to specify so that the application will be able to compute the location of the items copied.

These parameters are:

  • Instances & total angle: the application computes the angular spacing after you specified the number of instances you wish to obtain and a total angle value.
  • Instances & angular spacing: the application computes the total angle after you specified the number of instances you wish to obtain and an angular spacing.
  • Angular spacing & total angle: the application computes the instances you can obtain by specifying an angular spacing and a total angle.
  • Complete crown: the application computes the angular spacing between the instances you decide to obtain.
  • Instances & unequal angular spacing:  distinct angle values can be assigned between each instance.
  • If you set Instances & total angle or Angular spacing & total angle parameters, note that you cannot define the total angle when using formulas.
  • The Keep specifications option is not available if you are patterning a pattern.

  1. Set the Instances & Angular spacing options to define the parameters you wish to specify.

Choosing Instances & Angular spacing dims the Total angle field because the application no longer needs this specification to space the instances.
  1. Enter 7 as the number of pads you wish to obtain.

  2. Enter 50 degrees as the angular spacing.

Reference Direction

  1. Click the Reference element field and select the upper face to determine the rotation axis. This axis will be normal to the face.
    To define a direction, you can select an edge, a line, a planar face or a plane. After selecting an edge, a line or a planar face, if necessary, you can also select a point to define the rotation center. If you select a plane, selecting a point is mandatory.

    Two arrows are then displayed on the pad.

Clicking the Reverse button reverses the direction.


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.

If you modify the angular spacing, the application previews the result: arrows 1 and 2 are moved accordingly.
  1. Click Preview: the pad will be repeated six times. The instances are green, just like the original feature.


Crown Definition

  1. Now, you are going to add a crown to your part. To do so, click the Crown Definition tab.

  2. Set the Circle & Circle spacing options to define the parameters you wish to specify.

  3. Enter 2 in the Circles field.

  4. Enter -18 mm in the Circle spacing field.

    This figure may help you to define your parameters:

  1. Click OK.
    These are your new instances:

  2. Now, you are going to modify the position of the initial pad. Such a modification will affect all instances too. Double-click the pattern.

  3. Extend the dialog box by clicking More.

  4. Enter 20 in the Rotation angle field.
    The application previews the rotation.


  • Applying the Delete command on one instance deletes the whole pattern. However, deleting the instances of your choice is possible when creating or editing the pattern. To do so, just select the points materializing instances in the pattern preview. Selecting these points again will enable the application maintain the corresponding instances.
  • The Simplified representation option lets you lighten the pattern 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. 
  • Remember then that clicking once or double-clicking an instance does not lead to the same result.
  1. Click OK.
    All instances are moved accordingly.

The scenario above does not show the use of the Radial alignment of instances option. In addition to performing the steps described, you could have used this option that allows you to define the instance orientations.

The option is checked: all instances have the same orientation as the original feature. The option is unchecked: all instances are normal to the lines tangent to the circle.
The application offers the capability of creating polar patterns (for example, spiral patterns). To do so, you need to define formulas. For more information about formulas, refer to the 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 menu item 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 Circular Pattern icon .
    The features are indicated in the Object field.

  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.


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.

Instances and Unequal Angular Spacing

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

  1. Set the Instances & unequal angular spacing parameter.
    Angular spacing values are displayed between each instance.

  2. To edit the values between each instance, you need to edit values individually. First, select the angular spacing of interest if not already done.

  3. Then, choose one of the methods described hereafter: For example, if you wish to change 50 degrees for 80 degrees for the angular spacing selected as shown in our picture, you can:

    • double-click the angle 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 Angular spacing field of the Circular Pattern Definition dialog box.
  4. Repeat the operation for the other angular spacings.

  5. Click OK when done.

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 as explained below:

  1. Select the UDF.

  2. Click the Circular Pattern icon .
    The application treats the pattern feature as a complex pattern, that is a pattern made from a list of diverse features. The Keep specifications option is enabled and dimmed. The created pattern you create keeps the UDF specifications.


  3. Click the Circular Pattern icon .

  4. Select the UDF.
    Here the pattern is treated as a single feature. You are free to enable or disable the Keep specifications option.

Note that:

  • you can pattern only one UDF.
  • patterning UDFs is allowed in Part Design, not in Generative Shape Design.
  • If you want to use UDFs as entities to be patterned, first click the Pattern command and then select the UDF. This will help you get better performance.

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.

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.