button is clicked in the dialog bar. Closed curve chaining will join a series of lines and arcs into a single closed curve with just a single click of the mouse. To enable this mode, make sure that Closed curve button is clicked in the dialog bar.
A closed curve forms a loop with the start and end points the same. This method tries to follow the shortest, smooth path around the geometry. The path it selects will be highlighted in thicker blue lines. To accept this curve, click Create button at the bottom of the screen. To reject this selection click the Clear Pieces button at the bottom of the screen or the Undo button in the Standard toolbar. If you are having problems creating your curve, you will probably have to provide more feedback by using the Pick curve pieces method.
How to chain lines and arcs into curves
Restrictions of using pick pieces (chaining) for creating curves
Troubleshooting pick pieces (chaining)
See also Clip, Curve join Working with Imported geometry.