#Primitives

A body without a sketch, from sizes alone. The buttons are in the “Primitives” group; the sizes are set at the geometry, Enter applies.

• Box (key B) — length, width, height.
• Cylinder (key Y) — diameter and height.
• Sphere — diameter.
• Cone — bottom diameter, top diameter, height. A zero top diameter gives a sharp cone, a non-zero one a truncated cone.
• Torus — ring diameter and tube diameter.
• Prism — the number of sides is set above, then the diameter and the height.

#Why bother when there is a sketch

Speed. For a roller, a boss, a pin or a blank a sketch is an extra step: the shape has nothing but two or three numbers, and those numbers are just as parametric as sketch dimensions.

#How they behave afterwards

A primitive is a material feature like an extrusion: it carries the single body of the part. A second primitive will not create a second body, it merges with the first.

#When a sketch is better

As soon as the shape stops being described by those numbers — a flange, a flat, a groove is needed — move to a sketch. Assembling a complex part out of primitives costs more than drawing an outline.