Coradial Relation
The Coradial relation puts two circles or arcs on the same center with the same radius, so they lie on one circle, and keeps them that way. It is Concentric and Equal in one relation.
When to Use It
- Keep an arc on the circle of a hole it was drawn around
- Lay two arcs of one slot end on the same circle
- Tie a sketch circle to a round hole in the part so it matches it exactly
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). This relation is not in the relation menus until you click Edit on the Sketch tab and tick Offer Pierce, Merge and Coradial when making relations.
- Click a circle or arc, then click the second circle or arc.
- Keep the pointer still for about half a second. A bar titled Add a relation to the N selected opens beside it. Rest the pointer on a button to read what it does. Click Coradial. You can also right-click the selection and choose Coradial under Make them, or click it under Add a relation in the Properties panel.
- The second piece moves onto the first one's center and takes its radius. A small green square marks the relation, and a message says Coradial added. It stays true as you move and resize; Edit, Constraints lists it. Ctrl+Z takes it back.
Options
| Setting | What it does |
|---|---|
| Two circles | The second circle moves onto the first and takes its size. |
| A circle and an arc, or two arcs | An arc moves as a whole onto the center, then grows or shrinks about its center to the radius, keeping how far round it runs. |
| More than two | Each one after the first is made coradial with the first. |
| Which one gives | The held piece stays and the other moves (see The Anchor Rule on the Relations page). |
| Afterward | Move or resize either piece, or type a size for either, and the other follows. |
Tips
- One Ctrl+Z takes the relation back and puts the piece where it was.
- Pieces that are already Concentric get only the Equal part added, and pieces already Equal get only the Concentric part; the list then shows that relation beside the one you had.
- If you only want the centers shared, use Concentric Relation. If you only want the sizes the same, use Equal Relation.
- A round hole in the part can be one of the two; it never moves, so the sketch piece comes to it.
If Something Goes Wrong
- "Coradial cannot hold together with the relations already there. Nothing changed." Something already placed fights it, for example a different diameter typed for each piece. Delete the one in the way from the list under Edit and try again.
- "Coradial already holds through the relations you have, so nothing was added." The pieces are already tied this way, for example by Concentric and Equal.
- "Both are edges of the part, which never move, so Coradial cannot make them one. Pick a circle or arc of your own sketch." At least one of the two must be a sketch piece.
- The button is not in the bar. Coradial is offered only when every piece picked is a circle or an arc.