there two ways of doing it:
1) to create 16 square cross sections (without rotation) per turn and later to join the surfaces with 'unite' tool. select 'rectangle1' , 'rectangle2' apply 'unite', select 'rectangle2_1' , 'rectangle3' apply 'unite', etc.
The result is linear segments with square section with a helix shape. The position of the n-cross section is:
xn: r cos (Φn) r: radius helix Φn: 0, pi/8 , pi /4 , ......
yn: r sin (Φn)
zn: n*pitch/16 pitch: height per turn
2) to create 1 square cross sections and create a Line with segments (xn,yn,zn) and later use tool 'swep along path' to generate all the helix at once.
regards, Dante from (Instituto Argentino de Radioastronomia)