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Bounding Box Export

This guide explains how to use CADshift’s bounding box export feature to add material size information to your DXF files.

What is Bounding Box Export?

A bounding box is a rectangle that fully encloses your part geometry. CADshift can add two types of bounding boxes to your DXF exports:

  1. Axis-Aligned Bounding Box (AABB) - Rectangle aligned with the X and Y axes
  2. Minimum Area Bounding Box (MABB) - Smallest possible rectangle at any rotation angle

These boxes help with:

  • Material size estimation
  • Nesting optimization
  • Stock allocation
  • Cost calculation

Types of Bounding Boxes

Axis-Aligned Bounding Box (AABB)

┌─────────────────┐
│    ╱╲           │
│   ╱  ╲          │
│  ╱    ╲         │
│ ╱      ╲        │
│╱________╲_______│
└─────────────────┘
  • Always aligned with X/Y axes
  • Quick to calculate
  • May be larger than necessary for rotated parts
  • Useful when stock material is pre-cut to standard sizes

Minimum Area Bounding Box (MABB)

    ╱─────────────╲
   ╱    ╱╲         ╲
  ╱    ╱  ╲         ╲
 ╱    ╱    ╲         ╲
╱    ╱______╲_________╲
╲                     ╱
 ╲___________________╱
  • Rotated to minimize area
  • Uses convex hull + rotating calipers algorithm
  • Optimal for nesting calculations
  • Shows true minimum material requirement

Enabling Bounding Box Export

  1. Open the DXF Export PropertyManager
  2. Click the Settings tab
  3. Scroll to the Sheet Metal Processing section
  4. Check Export bounding box

Smart Box Selection

CADshift intelligently determines which boxes to draw:

Part OrientationBoxes Drawn
Aligned with axesAABB only (MABB would be identical)
Rotated/diagonalBoth AABB and MABB
Complex geometryBoth boxes for comparison

This prevents redundant overlapping boxes when they would be the same.

Layer Configuration

Bounding boxes are placed on a dedicated layer. Set its name and colour on the Bounding box row of your Output Profile’s Layers grid:

  • Bounding Box Layer - Set custom name and color
  • Typical names: “BOUNDING_BOX”, “MATERIAL_SIZE”, “NESTING”

Tip

Use a distinct color (like magenta or cyan) for the bounding box layer so it’s easy to identify and hide/show in your CAD software.

Use Cases

Material Estimation

Quickly determine the minimum sheet size needed:

Part: Bracket-001
AABB: 150mm x 200mm
MABB: 142mm x 185mm

Minimum stock: 150mm x 210mm sheet (with margin)

Nesting Optimization

Import DXF files into nesting software with bounding boxes to:

  • Pre-calculate fit on sheets
  • Optimize rotation angles
  • Reduce material waste

Cost Calculation

Use bounding box dimensions for quick cost estimates:

  • Material cost = Area × Price per unit area
  • MABB gives most accurate material usage

Quality Control

Verify part sizes match specifications:

  • Compare bounding box to expected dimensions
  • Quickly identify scaling issues

Dimension Annotations

When bounding box export is enabled, CADshift can also add dimension text showing the box sizes. This is controlled by the metadata export settings.

Example annotation:

AABB: 150.00 x 200.00 mm
MABB: 142.35 x 185.20 mm

Algorithm Details

Axis-Aligned Box

  1. Find minimum and maximum X coordinates
  2. Find minimum and maximum Y coordinates
  3. Create rectangle from these extents

Minimum Area Box

  1. Calculate the convex hull of all geometry points
  2. Apply rotating calipers algorithm
  3. Test rectangle at each hull edge orientation
  4. Return the rectangle with smallest area

The rotating calipers algorithm guarantees finding the optimal minimum-area rectangle in O(n log n) time.

Workflow Example

Step 1: Enable Export

  1. Open DXF Export settings
  2. Check Export bounding box
  3. Configure bounding box layer name

Step 2: Export DXF

  1. Select your parts
  2. Click OK to export
  3. Open the resulting DXF file

Step 3: Use the Data

In your CAD or nesting software:

  1. Isolate the bounding box layer
  2. Read dimensions from the box geometry
  3. Use for material planning

Best Practices

  1. Use consistent layer names - Makes automation easier
  2. Include in file naming - Add <AABB_WIDTH>x<AABB_HEIGHT> to filenames
  3. Set appropriate precision - Match your manufacturing tolerance
  4. Hide for production - Turn off bounding box layer before cutting

Troubleshooting

Bounding box not appearing

  • Ensure Export bounding box is checked in settings
  • Verify the bounding box layer is visible in your DXF viewer
  • Check that geometry exists to create a box around

Box seems too large

  • Check for stray geometry (hidden lines, construction geometry)
  • Enable Laser cutting optimization to remove unwanted entities
  • Review all layers for unexpected geometry

MABB same as AABB

This is correct behavior when your part is already aligned with the axes. The MABB is only drawn separately when it would be different (rotated).

Bounding box dimensions can be used in:

  • File naming - Include box dimensions in the filename
  • Metadata export - Embed dimensions as text in the DXF
  • Custom properties - Reference in SOLIDWORKS custom properties

Next Steps

Next
Metadata Export
CADshift

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