twich during perimeters

Hi,

here is a video of what is happening. Basically, there is a kind of involuntary movement of the extruder, at least a undesirable one. I think it’s probably my mistake in slic3r, but which one? Is it because I specified a Z lift variable in the extruder section? Or is it something else that found it’s way into the Gcode?
FYI I used to print this piece without this ever happening, but it was in ABS, and now it’s PLA . I probably did something wrong in Slic3r…
cheers

and the video:
http://youtu.be/elZJOJ-gPQ4

The extruder is set by default to retract filament when it moves from starting point to starting point to prevent stringy plastic blobs leaking from the hot end as it moves from location to location. You can turn that off by messing with the retraction settings, but I would leave it as is. That’s what you are seeing in that video. THe extruder reverses the filliament quickly to pull the molten plastic back into the nozzle. The suction from the unmelted portion of the filliament acts like a plunger to suck the molten plastic back from the nozzle end while it is in motion over areas that should not get plastic.
The retraction is basically the equivalent of turning off a water hose before you move the hose from one plant to another. If you don’t do that, you end up with water all over between the two plants.

Ok but what does the retraction have to do with the XY movement of the printhead? I am guessing you spotted the obvious fast xy jerk/twitch after every perimeter.
Do you mean that X and Y movements also participate in the retraction?

Looks like it runs the perimiter of the small posts, goes back and forth a ferw passes to fill the center, then goes around the larger circle, travels to the far side to fill in a spot over on the other side, then continues to fill in. Looked fairly normal overall to me except for that one small travel over to the other side of the large circle, and that could be related to the model, related to the slicing path, etc. It also looks like you have “start perimiters in a different spot” turned on so it is starting the new layer in different locations.

You can set the printer to do all the perimiters first and then go back and infil things, or perimiter and infil each of the major areas of the layer individually. It looks like the latter is set in this instance.

Post the file and the gcode, maybe someone can spot something that might be causing that one extra travel. Or maybe i’m not seeing what you are referring to.

How should I post it? Gcode is over 10mb and it wouldn’t go in attachment
btw
thank you for the elaborate response

You may want to reslice the model to see if that movement is repeated.

Also, what’s the current setting of:

Slic3r > Layers and perimeters > advanced > Avoid crossing perimeters ?

Avoid crossing perimeters is off. I turn it of because of faster slicing.