Laser / Plasma / Waterjet Cutting

A. What is Laser Cutting?

Laser cutting uses a high-energy laser beam to precisely cut materials

How Laser Cutting Works

A laser cutter uses a high-energy laser beam to cut materials. Common materials include acrylic, wood, and thin metal. Laser cutting offers very high precision with smooth, clean edges.

Kerf

Kerf is the width of material removed by the laser, typically between 0.1-0.3mm. You need to account for kerf in your designs:

From 2D to 3D

Laser cutting can only cut flat materials, but you can assemble flat parts into 3D structures. Common joining methods:

• Mortise and tenon joints — Parts interlock with each other
• T-slot joints — One part slides into a slot in another part
• Finger joints / box joints — Edges are made into interlocking teeth

Laser-cut 2D parts assembled into a 3D robot lift mechanism — test geometry with cheap material first, then cut from acetal for the final version

Plasma and Waterjet Cutting

Plasma cutting and waterjet cutting work on similar principles but can cut thicker metals. Plasma uses a high-temperature plasma arc; waterjet uses high-pressure water mixed with abrasive. The design principles are the same — both are based on 2D profile cutting.

B. Laser Cutting Design Tips

Design in 3D in Onshape, then export 2D faces for cutting

Onshape is Flexible

You can design with a full 3D model in Onshape, verify that all assembly relationships and dimensions are correct, then export the faces that need cutting as 2D files. This is less error-prone than drawing 2D directly.

Laser-Cut Box Example

A common exercise is designing a laser-cut box. The workflow is:

1. Build a 3D box model in Onshape
2. Use the Split feature to break the 3D model into flat parts
3. Add joining features (mortise and tenon / finger joints) to each face
4. Export the 2D profile of each face

Using Shell to split a 3D box model into flat parts ready for laser cutting

Custom Features

The Onshape community provides many custom features designed for laser cutting that greatly simplify the design process:

Adding community custom features to your toolbar in Onshape

• T-Slot Joints — Automatically generates T-slot joint structures on part edges
• Laser Joints — Automatically creates finger/box joint structures on the edges of two parts
• Thicken — Adds thickness to flat parts, turning 2D sketches into solid parts

T-Slot Joint custom feature: automatically generates T-slot connection structures on part edges

Laser Joints: automatically generates finger/box joint structures on part edges for glue bonding

Use Thicken to turn a face into a solid part, then add Laser Joint connections

More Useful Features

Beyond joining structures, there are other custom features that help optimize laser cutting designs:

Lighten custom feature: automatically generates weight-reduction holes on parts while maintaining strength

Sheet Metal Model: unfold a 3D bent part into a flat pattern for laser cutting, then bend after cutting

Kerf Bend: adds dense kerf lines to a flat pattern, allowing flat material to bend

Weight-reduction holes and custom sketches can also be added to unfolded flat parts

C. Exporting Cutting Files from Onshape

Use Auto Layout to automatically arrange parts and export DXF

Exporting DXF

Right-click a part face → Export as DXF to export the 2D profile needed for laser cutting

Auto Layout Custom Feature

Auto Layout is a very useful community custom feature that automatically arranges multiple parts on a sheet of material to maximize material utilization.

Auto Layout automatically arranges multiple parts on a sheet to maximize material utilization

Single Sheet Export

Single sheet export: Create drawing → Choose Custom template → No border or title block → Insert Part Studio

1. Select the face of the part to export
2. Right-click → Export as DXF
3. Verify the exported lines are complete

Multi-Sheet Export

If there are too many parts for one sheet, you'll need to group and arrange them, then export sheet by sheet.

Multi-sheet: Create Assembly → Insert Part Studio → Use Display State to group parts by sheet

Create a drawing page for each Display State; each page corresponds to one sheet of parts

Duplicate drawing page → Right-click view to switch Display State → Each page corresponds to a different sheet

Color Coding

Many laser cutting services require different colors to distinguish operations:

• Red — Cut lines (cutting through the material)
• Blue — Score lines (surface engraving only)
• Black — Raster engraving (filled areas)

Use different colors to distinguish cut lines (red), score lines (blue), and raster engraving (black)

Export Formats

• DXF — The most commonly used format for laser cutting
• SVG — Some cutting services also accept this format