Where an Extrude Stops
Use the Up to field on an extrude to say where the prism stops: Blind (distance), To next face, To selected face, or Through all. Reach for one of the last three when the honest answer is "as far as the part is thick" rather than a number you type and then have to maintain.
The four ends
| End condition | Where the prism stops |
|---|---|
| Blind (distance) | Exactly where the Distance field says |
| To next face | At the first thing in the way |
| To selected face | On a face you pick, and it follows that face if it moves |
| Through all | Past the furthest body along the direction |
Blind is the default and the only end that needs a number. Choose any of the others and the Distance field disappears, because the model is answering that question now.
Through all makes the prism long enough to leave nothing behind and lets the boolean clip it back. It runs a millimetre past the furthest body it can see along the sketch normal, and a generously long way when it can see none in front of it, as happens to a cut sketched on a face. Thicken the plate afterwards and the hole is still a hole. It does need something to cut, and a subtract with no bodies in the document at all says so rather than guessing.
To selected face is the one that pays off later. The distance is re-read from that face on every rebuild, so a lid that moves takes its bosses with it. Pick a face behind the sketch and the prism runs backwards to reach it, because the target wins over the arrow. The pick also remembers which body you clicked on, so two identical bosses, or the two halves of a mirror, no longer resolve to the wrong one.
Two things it will not do quietly. The target has to be flat: a cylinder or a fillet has no single plane to stop at, so rather than stopping somewhere inside the curve the step refuses the face and says it needs a flat one. And a target smaller than the profile you are extruding at it is legal but flagged — the prism stops at that face's plane rather than at its edge, which is often not what the pick looked like it meant. The body still builds; the step carries a warning so you can decide.
Not every end works with every direction
| Direction | Blind | To next face | To selected face | Through all |
|---|---|---|---|---|
| One direction | ✓ | ✓ | ✓ | ✓ |
| Symmetric | ✓ | — | — | ✓ |
| Two directions | ✓ | — | — | — |
The editor keeps you inside that table rather than letting you find out later. Unavailable ends are shown but not selectable, and changing the direction to one that cannot support the current end resets it to Blind. Adding material narrows it further: an Add extrude offers only Blind and To selected face.
Start from: beginning somewhere else
Use Start from to begin the prism somewhere other than the sketch plane. It has two modes, and the field under it changes with the one you choose.
A distance is the plain version. It slides the start along the direction: positive forward, negative back, up to 500 mm either way.
A selected face measures it instead. Pick a face and the prism starts there on every rebuild, exactly the way To selected face ends there — it is the same measurement, signed in the same frame, so a face behind the sketch starts the prism behind it and a start face and an end face can never disagree about where a face sits. The same three refusals apply: a face that has been deleted, a face lying in the sketch plane itself, and a curved face, which has no single plane to start at. Until the first rebuild has actually measured it, the height arrow draws flush with the sketch plane, because at that moment the real number does not exist yet.
Reach for either when one sketch has to drive a feature that lives somewhere else: a boss standing off a plane, a pocket that starts below a surface, a cut that leaves a skin. Under To selected face the offset is taken out of the distance rather than added to it, so the prism still ends exactly on the face. It moves where the prism starts, never where it stops — and if it moves the start all the way onto the end, the extrude has no length left, and the step says so rather than building nothing.
See also
- Extrude and Cut: regions, direction and the combine modes
- Cut and Push Face: the same fields with no sketch at all