Since most coil springs are held in place by flat surfaces at each end, I've shown an easy way to model ground ends to provide a flat surface on the spring too. Alfred's model - http://www.3dvia.com/sady2/models/2B6ACF2133051729 - shows this too.

I started my spring with a 180 degree revolve, then mirrored it and rotated each piece (before joining) 7 degrees in opposite directions for a total pitch of 14 degrees. To join them I drew a centerline on the end surface of the receiving end in order to join them properly. If you open the model in Shape you'll see that the revolve segments do not line up because they are pitched differently. That is why you need to build each layer of your spring by joining them using the center point of the faces.