AutoCAD Compound Curves Tutorial

The regular version of AutoCAD doesn't have a "Compound curves" function as AutoCAD Civil 3-D does. However, AutoCAD does have a function called "Blend curves" that performs the same operation as "Compound curves." Use "Blend curves" to create a smooth bridge between two separate curves. This bridge and the two curves form a compound curve. "Blend curves" produces a Bezier curve, witch has fit points and control points you can move to adjust the curve. The fit points connect the Bezier to other curves, and lie on the Bezier curve. The control points don't lie on the Bezier curve, but influence its shape.

Instructions

1. • 1
     Click the "File" menu, and then click the "New" command to display the dialog box for creating new documents. Click "Open" to open the default template for new documents. AutoCAD will display a new canvas for you to draw on.
   • 2
     Type "arc" to enter the mode for drawing arcs, and then click a point on the canvas to plot the first endpoint of the arc. Drag the mouse to another canvas location, then click the mouse again to plot a point that will lie on the arc. Drag the mouse to specify the arc's radius, and then click the mouse to complete the arc.
   • 3
     Draw another arc that has an endpoint close to one of the endpoints of the first arc, and then click the "3-D modeling" item from the "Workspace" drop-down list at the top of the application window. Though the "Blend curves" command is a 2-D object rather than 3-D, the 3-D modeling workspace allows quick access to "Blend curves" through its icon in the "Surface" tab.
   • 4
     Click the "Surface" tab to display a list of panels for creating and modifying 2-D and 3-D surfaces. Click the top right icon in the "Curves" panel to run "Blend curves." Click the first arc you made, and then select the second arc you made in the same way. AutoCAD will create a new Bezier curve that smoothly links the first and second arcs. However, the arcs and curve remain as three separate objects. Dragging one or more of them to a new screen location will separate the linked objects.
   • 5
     Click the canvas on a location near the arcs and curve, and then drag the mouse to surround the objects with a rectangular selection region. Right-click the mouse and click "Group" to connect all three objects. You can now move all three objects by clicking and dragging any one of them.