-First draw the circle that is the centre of the involute
-Decide where you will start on that circle drawing your involute.
-Then at equal intervals of about 15 degrees radially about that circle draw lines tangential to the circle, from its radius, and extended to a length equal to the arc length from the start point on the circle to the point you're working on. for more than a full rotation around the circle you'll have to add the circumference in length to the extension lines for each extra rotation around the circle.
-The first line will be 0 length, and the line at 360 degrees will be equal to the circumference of the circle.
-Once you have some lines around the circle, use your endpoint snap, and draw a 2d polyline starting from the origin point on your circles radius, to the endpoints of the lines.
-To smooth the polyline use the command 'pedit', then select the polyline. Use the 'fit', or 'spline' to smooth the curve. The properties display also has control for the curve fitting also.
