Slicer Print Settings - What did I do wrong?

[old man emu]

I'm after a review of the print settings I am using for my slicer software (it's Slic3r)

I can't upload the stl file because it is too big, however, think of it as a snub-nosed bullet with a cartridge case that tapers towards the rear. There are four helical vanes which run from the nose of the bullet to the join between the bullet and the cartridge case. (I hope that is clear).

Here are my Print Settings:

Print Settings (Large).jpgPlease save this file to your desktop and view it from there. It's too small to view here.
This is the print I get:

Printed object showing walls.jpg This is the object with support walls


Printed object - base layer.jpg This is the base layer



Base with layer one removed.jpg This is the base with the linear threads removed.

My question is: Can I define settings for the printer that will stop it printing such a lot of material on the outside of the object?

Does it really need me to specify that the slicer software creates support material?

Old Man Emu