Design Nomenclature / Form & Geometry
Extrude
Also called extrusion, pull, prism
This entry has not been translated yet and is shown in English.
Sweeping a profile along a straight path, generating surface behind it. A closed profile extruded gives a prism — the operation that makes a cube from a square and an I-beam from its cross-section. In a mesh, extruding a face leaves the original face's edges as a new loop; leaving that face itself in place is what buries an internal wall.
In practice
The word carries over exactly from the shop, where aluminium extrusion is the same act performed through a die. If a form has a constant cross-section, saying 'it's an extrusion' tells a fabricator what to quote.
Not to be confused with
- SweepMoving a profile along a path curve, generating surface as it goes, with the profile's orientation set by a rule — held fixed, kept normal to the path, or governed by a second rail. A revolve is the special case where the path is a circle about an axis; an extrude is the case where it is a straight line.
- LoftBuilding a surface through a series of profile curves placed along a form — the skin passes through each section rather than dragging one along a rail. Section count, section ordering, and matched start points govern the result; mismatched point counts or reversed curve directions produce the classic twist. With two sections it degenerates to a ruled surface.