Centre origin

Move the origin of a group, modified part or component to its middle, without moving anything.

Every object has an origin: the point its Position numbers describe, and the point a typed Rotation or Scale turns and grows it about. A shape’s origin is its own centre.

Older parts can have theirs far away. A group, a modified part or a component used to take its origin from wherever the world’s zero point was when it was made, and carry it along from then on. On a part built up high and then laid flat, that point can end up well outside the part — and typing a rotation then swings the whole part around it. Parts made now start with their origin in the middle, so you only need this for older ones.

Centre origin puts it back in the middle. Nothing moves on screen: everything inside shifts the other way to stay exactly where it is — the parts of a group, the edges and faces a modifier was built from, and every copy of a component. Mates attached to the part move with it. One undo reverses it.

It leaves a few parts alone, and says why. A part whose position, rotation or scale comes from a formula keeps its origin, because moving the origin would move the part. So does one whose mate follows a shape’s own size, because that mate has nothing to move with.

1. Select a group, a modified part (rounded, hollowed…) or a copy of a component.
2. Open Orient → Centre origin (it is in the right-click menu too).
3. The origin moves to the middle of the part. The part itself stays exactly where it is.