How to Create Solids Using the EXTRUDE Command in BricsCAD
Quick answer: EXTRUDE creates 3D solids from closed 2D entities, solid faces, regions, or closed boundaries, either adding volume to build a new solid or removing volume to cut one. In surface mode, it creates 3D surfaces from 2D entities like lines and polylines instead.
What Can Be Extruded
Closed 2D entities and regions, plus closed boundaries either in the XY-plane of the current UCS or directly on a solid’s face. With the Enable Boundary Detection option on the Selection modes toolbar active, closed boundaries get recognized automatically. Only closed polylines, circles, ellipses, and splines count as closed entities for this purpose.
Using EXTRUDE in Solid Mode
- Hover over the entity or subentity.
- Choose Solid Extrude in the Model tab of the Quad.
- You’re prompted for the extrusion height, or to choose from several options: Direction, Path, Taper angle, Auto, Subtract, Create, Unite, Both sides, Align, or set Limit.
- The Extrude Hotkey Assistant appears with these options, the default is marked with a blue frame:
| Option | What it does |
|---|---|
| Auto | Result depends on extrusion direction and three variables in the Extrude mode group: EXTRUDEOUTSIDE, EXTRUDEINSIDE, and INTERSECTEDENTITIES (0 = do not modify, 1 = subtract, 2 = unite). Their default values depend on workspace: 0 in Draft and Modeling, 1 in Mechanical and BIM. In Mechanical or BIM with default settings, extruding an entity inward subtracts volume from the main solid |
| Create | Always creates a new volume from the existing solid, regardless of extrusion direction |
| Subtract | Subtracts the new solid from every existing solid it interferes with |
| Unite | Unifies the new volume with every existing solid it interferes with |
| Both sides | Creates symmetric volumes in both directions from the main solid at once; type B at the Command line as a shortcut |
Select an option, move the cursor to set the extrusion direction (it extrudes dynamically as you move), then set the height by clicking a point, typing a value in the dynamic dimension field, or using the Limit option. Press Enter or right-click to accept.
Using EXTRUDE in Surface Mode
- Hover over the entity or subentity.
- Choose Surface extrude in the Model tab of the Quad.
- You’re prompted for the extrusion height, or to choose Direction, Path, Taper angle, Auto, Create, Slice, Both sides, or Align.
- The Extrude Surface Hotkey Assistant appears with these options:
| Option | What it does |
|---|---|
| Auto | When multiple touching entities or subentities are selected, result depends on UNITESURFACES. On, touching surfaces unite into one; off, each creates its own separate surface. Default depends on workspace: 0 in Draft and Modeling, 1 in Mechanical and BIM |
| Create | Creates new surfaces |
| Slice | Cuts through solids using the extruded surface, similar to the SLICE command |
- Select an option, move the mouse to set the direction, and enter a value in the dynamic dimension field.
- Press Enter or right-click to accept the surface.
Frequently Asked Questions
What entity types can actually be extruded as a “closed entity”? Only closed polylines, circles, ellipses, and splines, not, for example, a closed shape made only of separate line and arc entities that aren’t joined into one of those.
Does the Auto option behave the same way in every workspace? No, the underlying variables it depends on (EXTRUDEOUTSIDE, EXTRUDEINSIDE, INTERSECTEDENTITIES for solids, UNITESURFACES for surfaces) default differently: 0 in Draft and Modeling workspaces, 1 in Mechanical and BIM.
How do I create symmetric volumes extending both ways from a solid at once? Choose Both sides in the Hotkey Assistant, or type B at the Command line while extruding in solid mode.
Can surface mode extrusion cut through an existing solid? Yes, using the Slice option, which works similarly to the SLICE command.