Cannot print without support

I am able to print all mendel90 parts via kisslicer except x-motor-bracket. So to print it without support I used slic3r.
But I failed when printing large bridge surface. The bridging thread did not always touch opposite perimeter. So I got blobs and head strike.
I noticed that part was designed for attaching bridges only to external rectangle perimeters but not to internal rectangle breakout structure.
Does anybody experience this problem?
Is it reasonable to add perimeter step for attaching bridges to central rectangle?

; generated by Slic3r 0.9.9 on 2013-04-23 at 09:30:11

; layer_height = 0.40
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.5
; perimeter_speed = 30
; infill_speed = 40
; travel_speed = 80
; nozzle_diameter = 0.5
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.60mm
; infill extrusion width = 0.55mm
; solid infill extrusion width = 0.60mm
; top infill extrusion width = 0.60mm
; first layer extrusion width = 1.00mm

Edited 3 time(s). Last edit at 04/24/2013 01:29PM by karabas.

I could be wrong here, but I was under the impression even nophead used support when printing this part (I thought I read it somewhere).

Plus to add to that I've seen a few posts saying slic3r 0.9.9 possibly has issues with bridging, which probably doesn't help.

The central support is 2 filaments wide. I print all the parts with a single outline so the infill overlaps the support by one filament width which works perfectly.

Skeinforge doesn't realise it is a bridge and just does normal diagonal infill.

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[www.hydraraptor.blogspot.com]

Sorry I fogot it's all for skeinforge.

Does it work in Slic3r if you make perimeters 1?

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[www.hydraraptor.blogspot.com]