Parametric helical surface

Mbert

Dear colleagues,

I am trying to parametrize a surface that follows an helix. The basic equations for this surface are:

x = R1*cos(theta)
y = R1*sin(theta)
z = B1*theta + h

where "theta" and "h" are the parameters and R1 and B1 are constants. I am looking for the parametrization of this surface, but skewed, so that the left and right edges (at theta_min and theta_max) are normal to the helix, instead of being parallel to Z (and the other 2 edges remain parallel to the helix).

At the moment, I use a FOR loop to modify the vertices to skew my surface, but I was wondering if there was a more straightforward way, through a new parametrization.

Best regards,
M.