spring = helix(pos=(0,2,1), axis=(5,0,0), radius=0.5)

The helix object has the following attributes and default values: pos (0,0,0), x (0), y(0), z(0), axis (1,0,0), length (1), radius (1), coils (5), thickness (radius/20), color (1,1,1) which is color.white, red (1), green (1), blue (1), material, and up (0,1,0). 

At present, setting just the x, y, or z component of the axis of a helix does not update its appearance; it is necessary to assign a complete vector to the axis of the helix.

Note that the pos attribute for cylinder, arrow, cone, pyramid, and helix corresponds to one end of the object, whereas for a box, sphere, or ring it corresponds to the center of the object.

Currently it is not possible to specify the opacity of a helix object, which is based on the curve object.

See description of Additional Attributes available for all 3D display objects.