Pattern Geometry is a huge time saver and when used correctly, can bolster your models robustness greatly. You can probably visualize what the purpose of the Pattern Geometry function is just by it’s name. This function will take any pre-existing geometry and repeat it from 1 to n number of times over eight different pattern layout options.

This function can be found by default here: Menu->Insert->Design Feature->Associative Copy->Pattern Geometry.

Upon opening the Pattern Geometry function window, you are presented with the following rollouts. By default the “Linear” type is selected. All the many options to fully customize a linear pattern definition are displayed beneath the Layout type definition. Depending on which Layout is selected, these options will change to accommodate that function type.

Below are the eight types of patterns you can create in NX 10:

• Linear
• Circular
• Polygon
• Spiral
• Along
• General
• Reference
• Helix

Each type is specific to a certain layout pattern, using one of these eight options will allow you to create virtually any type of patterned layout possible. We will go through each and show examples of how you can create patterns of varying types depending on your need.

Below are the types of geometry you can pattern with this function:

CSYSes, Curves, Datums, Edges, Faces, Points, Sheet Bodies, and Solid Bodies are all able to be patterned.

---

Linear Pattern Type

Linear patterns are pretty straightforward. These are limited to varying types of patterns that lie strictly along one or two  vector directions. This is a “1D or 2D” layout type meaning a pattern can only be generated in at most two dimensions at one time.

The first thing with any type you use is to select the geometry you want to use. Either leave the Selection Filter pull-down menu to “No Selection Filter”, or change it to your desired type and click on the geometry in the graphics window. Here I have selected the solid rectangle seen below next to the absolute CSYS.

Reference Point: This determines the origin of your pattern. By default this will be the center of a solid or sheet, and the values you give in the next step are calculated off this point, treating it as (0,0) – You don’t need a third direction because only two vectors can be used. Here I left the reference point to be the center of mass of the solid.

Pattern Definition: Here is where all the values and types of the selected pattern are modified.

• Boundary: This is a good way to limit repetition of your pattern past a certain defining feature, either curves, curves defined from a face, or an internal boundary within which patterns will not be created.
• Direction 1: Here you will define the (mandatory) first direction. You must have a minimum of one direction for this function. Click on “Specify Vector” and select a vector of line to define your direction. As always you can create a vector “on the fly” by clicking the vector dialog options and creating a new vector as needed. Below I have selected the +Y vector with a count of 6 and a pitch of 4.
• Spacing: You have four options to define spacing, listed below:
  • Count and Pitch: Defines n number of objects spaced x distance apart, where n is the Count and x is the Pitch.
  • Count and Span: Defines n number of objects spaced over y total distance, where n is the Count and y is the total span. The pitch distance here is a function of the total span divided by the number of objects (p=y/n).
  • Pitch and Span: Defines n number of objects by dividing the total span y by the pitch distance x (n=y/x).
  • List: This is where you can highly customize your pattern according to a varying list. This is very useful when you want the number, pitch and span to vary across your pattern. Generally most patterns use one of the three above options, but List is there if you really need it. Thanks Siemens.
• Direction 2: A second vector can be used to create a 2D pattern. Below I’ve chosen the +X vector with a count of 4 and a pitch of 20.
• Pattern Increment: Displays a dialog allowing input of increments to be applied to instances as the pattern amount changes.
• Instance Points: Allows you to create an instance point for pattern repetition, allowing you to later edit those individual instances by clocking and deleting those instances. Clocking is the same as moving an individual instance.
• Orientation: Allows you to orient your pattern to a different CSYS or face direction.
• Pattern Settings: There are some neat options hidden in this last rollout. Staggering a pattern causes the even rows of your pattern to be moved such that the pitch distance along the direction is moved half the distance of one full pitch, causing a perfect offset from the odd rows.
• Settings: Check these boxes to allow parametric associativity to be applied to the geometry you are patterning, meaning that editing the patterned geometry will cascade down and affect the new pattern instances.

A staggered pattern along the Y vector

---

Circular Pattern Type

Circular patterns allow geometry to be spun around a central axis, and radiated outward from that same axis all in the same function. You can create some incredible results using this function type that bend the eye and fascinate the mind. This is my favorite function type by far.

As before, select the geometry to use, here the same rectangle is used again.

From this point on, I will only go over new options under the “Pattern Definition” rollout options, if you don’t see one listed, scroll back up and you can find it defined in the Linear Type section.

Pattern Definition:

• The Layout is now set to circular.
• Rotation Axis: This is the one axis you get to use with your pattern. The resulting geometry is spun around this axis according to the variables you enter. Above I have selected the Y axis as my rotation vector.
• Angular Direction: Note the key difference that no longer integer units are used, and have been replaced by degrees. This makes sense as each location is set according to a relating degree increment around the central axis. Above I have set my total span angle to be 270°. for a full circle set the span to 360°, 180° for half, etc. I’ve also set the object count to 40 to create 40 rectangles spaced evenly over the 270°.
• Radiate: This option will push additional concentric patterns radially along a plane normal to the rotation axis. If you want this option, enable “Create Concentric Members” and set your spacing accordingly. Above I’ve set a count of 2 (including the original) with a outward radial distance of 20 inches from each objects original location along it’s respective degree vector. By default, NX will hide the original ring and you need to check “Include First Circle” to show it.

Play with the options to see what kind of rotational patterns you can come up with.

---

Polygon Pattern Type

This option will allow you to create a pattern along an equilateral polygon around a single axis along with optional radially spaced concentric members like the Circular Pattern Type. This type is very similar Circular it just adds linear sides to the pattern instead of being perfectly circular.

The same rectangle is again selected as our patterning object. This time I have chosen the Z axis as my rotation vector.

Polygon Definition:

• Number of Sides: Choose how many sides your polygon will have. I wanted a dodecagon, so I chose 12 sides.
• Spacing: These options are again different from before
  • Count per Side: Defines the number of objects that will be equally spaced along one edge of the polygon.
  • Pitch along Side: Defines the number of objects (n) along a side by dividing the polygon edge length (l) by the pitch distance (x) (n=l/x).
• Span: Specifies how many degrees you want your polygon to rotate along until it cuts off. See the circular section above for more clarification.

 

---

Spiral Pattern Type

This is a really neat pattern type that I hardly ever see used. The mathematical formula behind creating a spiral is definitely a little tricky to wrap your head around if you have never done it before. Most spirals people draw are just doodles and there isn’t much thought into the mathematical laws that a curve must follow to be a true spiral.

Check out this awesome page dedicated to the math behind true spirals http://www.mathematische-basteleien.de/spiral.htm

We won’t go into the nitty gritty of all the spiral types here, but we will show you how to create a basic spiral pattern with NX.

Spiral Definition:

• Specify Plane Normal: Spirals are two-dimensional only (A helix is a 3D spiral). This option will define the support plane that the spiral path curve will sit on. I have chosen the XY plane here.
• Direction: Defines if the spiral should curve “right” or “left” outward from the origin point.
• Spiral Size By:
  • Total Angle: Using this option will create a spiral that rotates up to the specified number of degrees. You can see 1800° chosen above.
  • Number of Turns: You can see visually above that the spiral passes over the reference (Z) vector here five times. This equates out to be the same as 1800°. Use whichever option fits you best to define how many spirals you will have curving out from your origin point.
• Radial Pitch: This defines the distance outward that each pass over the reference vector will be. Here I have chosen 5 inches, meaning that each successive pass will be at a 5 inch increment along the reference vector from the previous pass. Larger pitch means a wider spiral.
• Pitch along Spiral: This will tell NX how many objects you want on your spiral. You only get a linear option (no degrees), which will instance a new object along the spiral curve when that distance is reached. Above I have specified a new object be patterned every 10 inches.

 

 

---

Along Pattern Type

This option will create a layout that follows a continuous curve chain and optionally a second curve chain (or linear vector). 

 

When the path that your pattern needs to follow is a variable curve, this option is what you will use. After the object is selected, you define the settings as follows:

• Layout type is set to Along
• Direction 1: Defines the path that the pattern will follow, above the yellow spline curve has been selected.
  • Path Method: There are three options to choose from depending on your needs.
    • Rigid: Object locations are calculate in a linear fashion from the reference origin point to the start of the path, then variably along the path.
    • Offset: Projects the input features location along a vector normal to the the path at the point on the path that is closest to the origin reference location.
    • Translate: Virtually moves the path along the shortest linear distance possible so that the closest start point of the path is now at the same location as the origin reference point.
• Spacing: Same as linear type, see above for details.
• Locations: Instead of a 1D directional, you now have two different options to define your count and pitch.
  • Arc Length: Defines the distance along the path as an integer
  • % Arc Length:  Defines the distance along the path as a ratio of the paths total length.
• Direction 2: You can use this option to instance the pattern again along another curve or along a vector. If you choose a curve, you have the same options as you did for Direction 1. If you choose a vector, the options are simpler and replicate what you would find in a Linear Pattern Type.

 

---

General Pattern Type

This pattern type is great for grid layouts or specific point-point patterns. It’s a great option when you have several different points in no particular patterned location and you want a variable pattern to put a piece of geometry in each (or some) of those locations.

After selecting your object to be patterned, you simply choose from one of two options in the Location menu:

• Point: Patterns the geometry from a point to another point(s) or CSYS(s), as many as you need.
• Coordinate System: Patterns geometry from a CSYS to point(s) or CSYS(s), as many as you need. Since CSYSs contain points anyway it’s kind of just a runaround to use this option, but I digress.

That’s pretty much it for General type. You have all the other customization like Instance Points, Orientation, and choosing your Reference Point as always.

 

---

Reference Pattern Type

This option will define a layout using the definition of an existing pattern. All that you need to do for this pattern type is to select a piece(s) of geometry that you want to pattern, then select the pre-patterned feature that you want to mimic.

By default, the Reference Point will be the center of mass of the geometry that you selected to pattern. If you select more that one piece of geometry, the reference point will be the center of mass of all of those pieces of geometry combined.

Pattern Definition:

• Select Pattern: Click on the feature in the graphics window you want to mimic. You can also select the feature in the Model History section under the Part Navigator.
• Select Base Instance Handle: This will be un-selected by default. You will need to click on an instance handle in the graphics window to define this. Instance points will be the small brown-gold spheres that represent each instance of the previous pattern.
  • The starting distance of the pattern being referenced is defined using the distance from the Reference Point  and the Base Instance Handle. All the other instances of the pattern then follow the original instance definition defined in the original pattern.

Again you can select Instance Points also if you want to later have more granular control over a unique instance by moving or deleting it.

Play around with changing the Reference Point and Base Instance Point to get a solid grasp on how the new pattern is defined via referencing the existing one.

---

Helix Pattern Type

Helix’s are defined as: “an object having a three-dimensional shape like that of a wire wound uniformly in a single layer around a cylinder or cone, as in a corkscrew or spiral staircase”.

To create such a geometrically radical feature like my “stairway to heaven” below, just follow the steps outlined.

Select the geometry to pattern, and change the reference point if you want it to be something other than the default.

Pattern Definition:

• Layout: Ensure the Helix type is selected.
• Rotation Axis: A helix needs a vector to rotate around. Above I have chosen the +Z vector.
  • Specify Point: By default this point will be located on the axis that you select for the rotation. However, you can change this if you want, which will move the axis virtually to the new point and change the rotation origin location
• Helix Definition:
  • Direction: Either choose a right or left-handed helix direction
  • Helix Size By: This is the most complex part of the process. There are five options to choose from. Each can ultimately accomplish the same result just using different variables.
    • Count, Angle, Distance: Defines the pattern by the number of object instances, the angle that each instance is located at along the helix, and the distance from one object to the next along the vector direction.
    • Count, Helix Pitch, Turns: Defines the pattern by the number of object instances, the pitch along the vector for one complete 360° rotation of the helix, and the number of complete turns to be made before the helix terminates.
    • Count, Helix Pitch, Span: Defines the pattern by the total number of object instances along the helix, the pitch distance of one complete 360° rotation about the axis, and the total span covered by the helix from start to finish.
    • Angle, Helix Pitch, Turns: Defines the pattern by the angle each instance is located at along the spiral about the axis, the pitch distance of one complete 360° rotation about the axis, and the number of complete turns to be made before the helix terminates.
    • Angle, Helix Pitch, Span: Defines the pattern by the angle each instance is located at along the spiral about the axis, the pitch distance of one complete 360° rotation about the axis, and the total span covered by the helix from start to finish.

Play with the options to see what fits your needs best, and enjoy your beautiful helical pattern that results.

---

Last but not least: Pattern Instancing

OK. We’ve covered all eight pattern types available in NX. Now I’d like to cover one of the most useful features within a pattern function, which is the ability to instance pieces of patterned geometry.

Instancing is done while the function window is still open. Below I have selected two instance points to manipulate. After selecting these two points, I can right-click on the instance and a shortcut menu will appear to either delete or clock that instance.

Below I chose to delete the upper one and clock (move) the instance beneath it up a few fractions of an inch. You can instance and edit as many pieces of patterned geometry as you like.

Essentially, instance editing allows you to grab and pick out unique instances in your pattern to edit them on the fly. It’s an incredible feature that saves you the hassle of having to create a whole other pattern geometry feature just to achieve that oddball result your looking for. Nice Siemens, really nice.

Till next time!

-Felix