messy overhang outer perimeter

Hi,

I have an ormerod 2 properly set up... at least it works perfectly with the whistle and the snowman. I made the ormaxis at the begining to calibrate it, but haven't reprinted it to check the correct calibration afterward.
Orthogonal parts print OK it seems, but as soon as there is a little angle (overhang), no matter if there is a support material underneath, the filament seems to retract and make kind of a brim (upward), until the hotend eventually hangs on it.
I tried this thing : [www.thingiverse.com]
and the centering cone from that one :
[www.thingiverse.com]
I interrupted the print after just a few layers to take some pictures.

I must confess that for this second part Slic3r couldn't handle the geometry, it crashed while generating the gcode, so I used Cura for the first time. Nice GUI, but I don't know all details about this program (I'm new to 3D printing anyway) so I don't know what parameters are set by default. The gcode generated by cura in automatic normal quality was used. I had to pause the print right after the begining because the hotend turned off after the homing of the 3 axis (?!), didn't find where in the gcode file... So I restarted it manually and let the print continue (it had not started to print at that time). I also confess that the filament I'm using is new and the previous tests were made using the one provided with my ormerod printer. So I didn't print the whistle again to test the filament itself, but the issue was already here with other rolls and other models.
PLA 1.75mm, 185°C hotend, 65° heatbed. Fan always ON (as it should ?)
The perimeter which is faulty seems to be on one side only.
And the base of the print seems bent on the picture but that's because I removed it from the bed without any care.

Can someone please tell me what I should do to improve things? I didn't identify the exact issue on the troubleshoot wiki page. I suppose it's just some form of an already documented problem, just don't know which one...

Edited 1 time(s). Last edit at 12/09/2014 05:09AM by mat_fr.

Just to complete the description: I tried to print a whistle to test the filament, it was ok (the first layer of bridged filament was a little bent downside but I don't know how it's supposed to behave so I assume it's not abnormal, the subsequent layers are flat).
I then tried to launch the spiral ornament (http://www.thingiverse.com/thing:210741) with support structure, and only one side (branch) gets "up", the one on the opposite side of the fan. Could the problem come from a too hot heat bed? On the picture it's not so bad (well the picture is, but the print not so much ), I had to stop the print because I had to leave and didn't want to leave the printer unattended. But the previous tests went to the point the hotend drags on the lifted part and the print is wasted.

Has anyone got an idea of what I could do to improve things? (apart from the quality of my pictures... )