Multiple support issues in stl

[mrvanes]

Version

slic3r-1.3.0-dev-1d97698-linux-x64

Operating system type + version

Ubuntu Zesty

Behavior

I'm facing several support issues in attached .stl, which is a real-world example of which I'm not sure deserve a separate topic or not. Please forgive me if this comes accross as rude, I just think the .stl is a good starting point for support improvement discussions.

To start, the design definately needs PR #3379 to create support that is both detachable and make the overhang stick to the interface layers while printing first top layer of the overhanging foot.

Secondly, it needs a multiple of twice the support extrusion width to not stick to the object (issue #1539, hard coded in SupportMaterial.pm @clip_with_object for now)

Third, for some reason I don't understand, the support height/width varies a lot over Z (in gcode preview at least, but the print shows these difference as well to some degree) if I set support material extrusion width to 120% (relative to auto default extrusion width). Using 'default' makes the support nearly unbreakable (using ABS). Setting it to a fixed (mm) value doesn't change this behaviour.

Fourth, allmost all support layers are printed with F3600, but only a few with F2000, which I also don't get and unnecessarily delay print time?

Sceenshot of the uneven support layer distribution:

Example stl showing the above issues
GymHook.zip

Used config
config.ini.zip