Assembly: an overview
An assembly places parts against each other. A part stays itself: it keeps its own history, its own sketches and its own single body — the assembly only says where it stands and how it moves.
Components
The assembly tree is made of components: parts and sub-assemblies. A double click goes inside a component, and from there you work with it like an ordinary part; the path on top shows where you are.
Joints
Position is set by joints, rules between parts, rather than by coordinates:
- Rigid — the parts are tied solid, zero degrees of freedom.
- Revolute — one axis of rotation: a hinge, a pulley.
- Slider — one translation along an axis.
- Cylindrical — rotation and translation along the same axis: a shaft in a plain bearing.
- Planar — two translations in a plane and a rotation in it: a part lying on a table.
- Ball — three rotations about a point.
- Pin-slot — rotation about one axis and translation along another.
- Parallel — holds the direction only; where the part sits is its own business.
A joint's anchor is inferred under the cursor: the middle of a face gives its centre, an edge its midpoint, a circular rim the hole centre, an edge end a vertex. You do not declare in advance what you are about to pick.
The parts are placed so that all joints hold at once. The properties of a joint show how many degrees of freedom the driven part has left, and if the joints ask something incompatible, the program says that they conflict.
Patterns, mirrors and clones
A row of bolts is placed by a component pattern — one row of the assembly timeline. The left bracket from the right one is a Mirrored copy of the part. Make a clone (the right button on the part in the tree) places the same part once more: editing the original changes the clone too, while it stands and mates on its own.
Interference check
A separate check shows where parts run into each other. On an assembly built from joints this is the first thing worth looking at before release.
Top-down design
One part's sketch can stand on another part's face — then an explicit external reference appears between them. That is how a bracket's dimensions come from the housing instead of being retyped into it. The reference shows in the properties of the part and can be broken — more.