How to Use Intersect in AutoCAD 3D: Step-by-Step Guide

In AutoCAD 3D, use the INTERSECT command to create a new 3D solid from the overlapping volume of two or more solids. Select the solids you want to intersect, and AutoCAD will generate the common volume as a new object.

Syntax

The INTERSECT command syntax in AutoCAD 3D is simple:

• Command: INTERSECT
• Select Objects: Choose two or more 3D solids that overlap.
• Result: AutoCAD creates a new 3D solid representing the volume common to all selected solids.

This command only works with 3D solids, not surfaces or meshes.

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Command: INTERSECT
Select solids: (select two or more overlapping 3D solids)
Result: New 3D solid of overlapping volume

Example

This example shows how to intersect two overlapping 3D boxes:

• Create two 3D boxes that overlap in space.
• Type INTERSECT in the command line.
• Select both boxes when prompted.
• Press Enter to complete.
• AutoCAD creates a new solid representing the overlapping volume.

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BOX 0,0,0 5,5,5
BOX 3,3,3 8,8,8
INTERSECT
Select solids: (select both boxes)
Press Enter

Output

A new 3D solid is created representing the volume where the two boxes overlap (from 3,3,3 to 5,5,5).

Common Pitfalls

Common mistakes when using INTERSECT include:

• Trying to intersect objects that are not 3D solids (like surfaces or meshes) - this will not work.
• Selecting solids that do not overlap - the result will be empty or no new object.
• Not selecting all solids before pressing Enter - only the selected solids are intersected.

Always ensure your solids overlap and are valid 3D solids before using INTERSECT.

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Wrong:
INTERSECT
Select objects: (select a 3D solid and a surface)
Result: Command fails

Right:
INTERSECT
Select objects: (select two overlapping 3D solids)
Result: New intersected solid created

Quick Reference

Step	Action	Notes
1	Type INTERSECT	Starts the intersect command
2	Select 3D solids	Choose two or more overlapping solids
3	Press Enter	Completes selection and creates new solid
4	Check result	New solid is the overlapping volume

Key Takeaways

Use the INTERSECT command to create a new 3D solid from overlapping volumes.

Only 3D solids can be intersected; surfaces or meshes will not work.

Ensure solids overlap before intersecting to get a valid result.

Select all solids before pressing Enter to complete the command.

The resulting solid represents the common volume shared by all selected solids.