Hi Pilou,
Bottlefeedarray2 is a step in creating the profiles cut in
the shaft as it travels along the screw.
If you produce a screw from just the bottle profile
by sweeping the bottle profile along the helix only
and then place a bottle in the thread and do a
Boolean subtract you will see it cuts into the thread.
That's because the bottle is vertical and not at the helix
Angle of the screw.

Cheers
Barry