Patterning features in computer-aided design (CAD) and computer-aided manufacturing (CAM) is a common way to quickly replicate geometry across a part. Two frequently used methods are linear patterns and sketched patterns. While both achieve similar end results in terms of repetition, they differ significantly in how they are created, controlled, and used in manufacturing workflows.

In this article, we will define linear and sketched patterns, compare their advantages, examine their use in part design and CAM setups, and guide engineers and machinists on when to use each technique.

What Is a Linear Pattern?

A linear pattern is a feature in CAD software that replicates a selected body, face, feature, or sketch along one or two directional axes. This pattern is typically defined by a specific distance between instances and the total number of copies.

For example, a row of holes spaced evenly along a block can be created by selecting the hole and applying a linear pattern along the desired axis.

Key Characteristics

• Defined by direction and spacing
• Usually applied to features or bodies
• Simple to control and edit
• Often used for symmetric or grid-style part layouts

What Is a Sketched Pattern?

A sketched pattern, also known as a patterned sketch or manual array, is created directly within a 2D sketch. Instead of applying a post-sketch feature pattern, the repetition is built into the sketch itself by copying or arraying entities like circles, slots, or rectangles.

This method gives the designer full control over each individual instance in the pattern, allowing for more complex and irregular arrangements.

Key Characteristics

• Built into the sketch geometry
• Allows uneven spacing and custom locations
• Useful for organic, non-repetitive layouts
• Often used when instances vary slightly in size or shape

CAD Workflow Comparison

CAM Considerations

In a CAM environment, both pattern types influence toolpath generation, cycle time, and machining strategy.

Linear Patterns in CAM

• Consistent toolpaths: Easier to copy operations across repeated features
• Efficient programming: One operation applied to multiple instances
• Better for probing and inspection: Known, repeatable positions improve metrology setup

Sketched Patterns in CAM

• Custom toolpaths: Allows flexibility for individual geometry variations
• More programming effort: Each instance might require its own operation if sizes differ
• Useful for molds, castings, or freeform parts

When to Use Each Pattern

Use Linear Patterns When:

• Geometry is identical and evenly spaced
• You want quick replication and parametric control
• Features need to align with machine coordinates
• Machining time needs to be optimized with repeated operations

Use Sketched Patterns When:

• Feature spacing is non-uniform
• Each instance needs slight variation
• Geometry is organic or does not align to standard axes
• Working with artistic, ergonomic, or biomimetic shapes

Design Tips

• Use constraints and construction lines when creating sketched patterns to ensure geometry remains parametric
• In linear patterns, always verify the extent of the pattern does not interfere with other features
• Combine both methods if needed: start with a linear sketch pattern and convert it to geometry before applying additional edits

Conclusion

Both linear and sketched patterns are powerful tools in CAD and CAM, but they serve different design intents. Linear patterns are ideal for simple, repetitive tasks where consistency is key. Sketched patterns offer greater flexibility for creative or functionally unique layouts. Understanding the strengths and trade-offs of each method ensures smarter design and more efficient manufacturing.