How to Draw a Spiral Curve in AutoCAD
One approach to drawing spirals in AutoCAD is to use the program's "Arc" and "Blend Curves" tools. You'll need to adjust this shape's control points to produce a smooth spiral. Once you finish your spiral, you can edit it as you would curves made with the "Spline" tool. Move the control points to change the spiral's shape.
Click the "File" menu. Select "New." Click "Open" to accept the default template and create the document.
Type "Arc" to run the tool for drawing arcs, then click the cursor on the canvas to define the first of two points for the arc. Drag the cursor to another canvas location, then click again to drag the arc's second point. The arc begins at the first point you clicked, passes through the second point, and terminates at your cursor. These three points are part of a circle, though AutoCAD doesn't draw the complete circle.
Click to complete the arc, press the up-arrow key on your keyboard to return to the "Arc" command. Press "Enter" to re-run "Arc," then click a point near the first arc's end point. Complete the second arc as you did the first, with one exception. After clicking the mouse to define the arc's second point, drag the mouse to form an arc with a smaller radius than the first arc. This forms the first two segments of the spiral.
Click the "Surface" menu's "Blend Curves" tool in the "Curves" panel, then click the first arc you made to indicate you want to join this arc with another arc. Click the second arc, then press "Enter." AutoCAD will draw a new curve that smoothly joins the two arcs. The result is the beginning of a spiral.
Draw additional spirals using the same process, ensuring each new spiral's radius is smaller than the previous. Join each arc to the current spiral with "Blend Curves."
Drag your cursor around all arcs to select them. Right-click and select "Group" to join the arcs to each other and complete the spiral.