How to Use Subtract Command in AutoCAD 3D

In AutoCAD 3D, use the SUBTRACT command to remove the volume of one 3D solid from another. Select the solid you want to keep first, then select the solid(s) to subtract from it, and press Enter to complete the operation.

Syntax

The SUBTRACT command syntax in AutoCAD 3D is simple:

• First selection: Choose the 3D solid you want to keep (the base solid).
• Second selection: Choose the 3D solid(s) you want to subtract from the base solid.
• Enter: Press Enter to perform the subtraction.

This command modifies the base solid by removing the volume occupied by the subtracting solid(s).

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SUBTRACT
Select solids, surfaces, and regions to subtract from:
Select objects: (select base solid)
Select objects to subtract:
Select objects: (select subtracting solid(s))
Press Enter to finish

Output

The base solid now has the volume of the subtracting solid(s) removed.

Example

This example shows how to subtract a smaller cube from a larger cube to create a hollow space.

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1. Draw a large cube (e.g., 10x10x10 units).
2. Draw a smaller cube inside it (e.g., 5x5x5 units).
3. Type <code>SUBTRACT</code> and press Enter.
4. Select the large cube and press Enter.
5. Select the smaller cube and press Enter.
6. The smaller cube volume is removed from the larger cube.

Output

The large cube now has a hollow space where the smaller cube was.

Common Pitfalls

Common mistakes when using SUBTRACT include:

• Not selecting the base solid first, which causes the command to fail.
• Trying to subtract solids that do not intersect; subtraction only works if the solids overlap.
• Forgetting to press Enter after selections, which stops the command prematurely.

Always ensure the subtracting solid overlaps the base solid and follow the selection order carefully.

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Wrong way:
SUBTRACT
Select objects: (select subtracting solid first)
Select objects to subtract: (select base solid)
Press Enter
// Command fails or unexpected result

Right way:
SUBTRACT
Select objects: (select base solid)
Select objects to subtract: (select subtracting solid)
Press Enter
// Subtraction succeeds

Quick Reference

Step	Action
1	Type SUBTRACT and press Enter
2	Select the base 3D solid and press Enter
3	Select the solid(s) to subtract and press Enter
4	View the updated solid with subtracted volume

Key Takeaways

Always select the base solid first, then the subtracting solid(s) when using SUBTRACT.

Subtraction only works if the solids overlap in 3D space.

Press Enter after each selection to complete the command.

Use SUBTRACT to create complex shapes by removing volumes from solids.

Check your selection order to avoid command failure or unexpected results.