If you are working with 3D curves in AutoCAD, you may want to join them into a single polyline or spline. This can help you simplify your drawing, reduce the number of objects, and create smooth transitions between segments. In this article, we will show you how to use the JOIN command to connect 3D polylines, splines, lines, and arcs into a single polyline or spline.
What is a 3D Polyline
A 3D polyline is a type of object in AutoCAD that consists of one or more straight or curved segments. Each segment has a start point and an end point, and can have a different elevation or direction. A 3D polyline can be open or closed, and can have width or thickness. You can create a 3D polyline by using the PLINE command or by converting other objects into a polyline.
What is a Spline
A spline is another type of object in AutoCAD that represents a smooth curve that passes through or near a set of points. A spline can be created by using the SPLINE command or by converting other objects into a spline. A spline can have different types of fit methods, such as CV (control vertices), Fit (fit points), or NURBS (non-uniform rational B-splines). A spline can also be open or closed, and can have start and end tangents.
How to Join 3D Polylines and Splines
To join 3D polylines and splines in AutoCAD, you can use the JOIN command. This command allows you to select one or more polylines, splines, lines, or arcs that are located end to end, and join them into a single polyline or spline. The resulting object inherits the properties of the first object that you selected. Here are the steps to use the JOIN command:
Click Home tab > Modify panel > Edit Polyline.
Select a polyline, spline, line, or arc to edit. If you selected a spline, line, or arc, press Enter to convert the selected object into a polyline.
Enter j (Join).
Select one or more polylines, splines, lines, or arcs that are located end to end.
Press Enter to end the command.
Note: Spline-fit polylines return to their original shape when joined. Polylines cannot be joined into a Y shape. If the properties of several objects being joined into a polyline differ, the resulting polyline inherits the properties of the first object that you selected[^1^].
In this article, we have learned how to join 3D polylines and splines in AutoCAD using the JOIN command. This command can help you create smooth and continuous curves from multiple segments. You can also use this command to join 3D lines (geometry) in AutoCAD LT[^2^]. We hope this article was helpful for you. If you have any questions or feedback, please leave a comment below.
How to Edit a Joined Polyline
After you have joined 3D polylines and splines into a single polyline, you may want to edit it further. For example, you may want to change the width, the shape, or the position of the polyline. To edit a joined polyline, you can use the same JOIN command and select the Edit option. This will allow you to modify the polyline by entering one or more of the following options[^1^]:
Enter c (Close) to create a closed polyline.
Enter j (Join) to join contiguous lines, splines, arcs, or polylines.
Enter w (Width) to specify a new uniform width for the entire polyline.
Enter e (Edit Vertex) to edit a vertex.
You can also use other commands to edit a joined polyline, such as MOVE, ROTATE, SCALE, TRIM, EXTEND, FILLET, CHAMFER, and so on. You can access these commands from the Home tab > Modify panel.
How to Convert a Joined Polyline into a Spline
Sometimes, you may want to convert a joined polyline into a spline. This can help you create smoother and more flexible curves. To convert a joined polyline into a spline, you can use the SPLINE command and select the Fit option. Here are the steps to use the SPLINE command:
Click Home tab > Draw panel > Spline drop-down > Fit.
Select the joined polyline to convert.
Press Enter to end the command.
Note: You can also use the PEDIT command and select the Spline option to convert a joined polyline into a spline. However, this option will only work for polylines that have linear segments. If your polyline has arc segments, you will need to use the SPLINE command instead[^3^]. ec8f644aee