Why does a 3D solid become difficult to edit after using UNION?

[indiancad]

Have you ever combined several 3D solids with UNION, only to find that editing one particular part later becomes difficult?

Once separate solids are united, AutoCAD treats them as a single 3D solid. If you still need to modify individual components, I prefer keeping the original solids or using SLICE when I need to separate a specific portion.

For complex models, combining everything too early can make later changes harder.

How do you usually manage 3D solids when you know the model will need revisions later?

[lrm]

Unlike some solid modelers, AutoCAD does not readily provide the ability to go back and edit the primitives and olther solids that were used in Boolean operations.  The command SOLIDEDIT provides some feature for editing a solid.  Familiarize yourself with the command and its features.  Alternatively, I often use explode and then do some edit making sure I continue to define a closed (watertight) shape so I can then use SURFSCULPT to make the model solid.

[indiancad]

On 9/23/2026 at 6:37 AM, lrm said:

Unlike some solid modelers, AutoCAD does not readily provide the ability to go back and edit the primitives and olther solids that were used in Boolean operations.  The command SOLIDEDIT provides some feature for editing a solid.  Familiarize yourself with the command and its features.  Alternatively, I often use explode and then do some edit making sure I continue to define a closed (watertight) shape so I can then use SURFSCULPT to make the model solid.

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You're so welcome! It’s one of those things where having a few different workflows in your back pocket makes a huge difference, especially when a Boolean operation doesn't quite give you what you expected.