Midpoint Relation
The Midpoint relation holds a point at the exact middle of a line, and keeps it there when the line changes length.
When to Use It
- Hang a hole center halfway along an edge
- Keep a rib centered on a plate
- Tie a new line's end to the middle of another line
Step by Step
- Open a sketch and draw the pieces (see Lines, Circles and Rectangles). Sketching is part of modeling, which comes with the Pro plans.
- Click Select on the Sketch tab (or press S).
- Move the pointer over a piece until its dots show and click a point. Then click a different line, away from its dots.
- Keep the pointer still for about half a second. A bar titled Add a relation to the N selected opens beside it, with one button for each relation that fits. Click Midpoint. Instead of waiting for the bar, you can click Midpoint under Add a relation in the Properties panel. (The right-click menu needs a piece selected, so for points use the bar or Properties.)
- A small green square marks the relation on the sketch, and a message says Midpoint added. It stays true as you move and resize; Edit, Constraints lists it. Ctrl+Z takes it back.
Options
| Setting | What it does |
|---|---|
| Picks | One point and one line. The line must be a different piece from the one the point belongs to. |
| Result | The point moves to the middle of the line. The line stays, unless the point is on an anchored piece, and then the line moves. |
| Listed as | Midpoint. |
| Automatic | With Add relations while drawing on, snapping a new line's end to the middle of a straight side ties it there with this relation. |
Tips
- With the Node tool: click a point, hold Shift and click a line, then hold still. The bar offers Coincident and Midpoint (see Node).
- A Center Rectangle already uses this relation to hold its center point.
- Midpoint centers the point on the line only. To set it on a different place, use Point on Line Relation and a size.
- For points, use the bar or the Properties panel. The right-click menu needs a piece selected.
If Something Goes Wrong
- "Midpoint cannot hold together with the relations already there. Nothing changed." Something already placed (another relation, a typed size or a Fix) fights this one. Delete the one in the way from the list under Edit (see Edit Menu) and try again.
- "Midpoint already holds through the relations you have, so nothing was added." The sketch already forces this, so nothing more is needed.
- The button is not in the bar. The bar only lists relations that fit what you picked. Check what is selected in the Selected list of the Properties panel. If the panel says None fits this selection. Pick another point, piece or part edge with it., change the picks.
- "Midpoint applied once: the relation solver could not load, so it will not be kept." The piece moved once but nothing was stored. Check your connection and add it again.