Question: plot3d

I do an order as follows,

> restart;

m := 3; n := 1; A := .1; B := 0; C := .1; r := 0.5; L := 8; mu := proc (x, theta) options operator, arrow; A*cos(m*Pi*x/L-n*theta) end proc; upsilon := proc (x, theta) options operator, arrow; B*cos(m*Pi*x/L-n*theta) end proc; omega := proc (x, theta) options operator, arrow; C*sin(m*Pi*x/L-n*theta) end proc; with(plots); plot3d([r*cos(theta)-upsilon(x, theta)*sin(theta)+omega(x, theta)*cos(theta), r*sin(theta)+upsilon(x, theta)*cos(theta)+omega(x, theta)*sin(theta), mu(x, theta)], x = 0 .. L, theta = 0 .. 2*Pi)

In the pic I got,there are 2 Qs,

1. why the r/L is so large ,and if I change the r/L there is no differences between them?

2.the tube in fz direction, if I only draw the pic of with(plots); plot3d(mu(x, theta), theta = 0 .. 2*Pi, x = 0 .. L),that is what I expected pic of tube in fz,but in the first pic, the tube in fz doesnot change,although I change m

Thank you very much.