How to make 3D spring profile in AutoCAD
This video illustrates all the steps involved in making this 3D spring model
This is final rendered image of spring profile
And you will find complete video tutorial here https://www.youtube.com/watch?v=HxLBxDofRJ0
I selected arbitrary dimensions to make this model just to keep making this profile simple.
In a step spline has been converted to polyline before sweeping the circle over helix profile because it was returning error while sweeping on spline.