Odd vertical line when printing

I've just printed a rabbit off Thingiverse on my Mendel which is finally starting to give prints that at least resemble the file going in, however on this print I noticed this odd line and a equivalent on on the other opposite side.

The rabbit was sliced with Slic3r, using 0.4 layer height (I believe I have a 0.5mm nozzle)

In the imgur album is the photos of the rabbit and line line (you can clearly see the line on the right side of the image when the rabbit is pointing to the left)

The photos:
[imgur.com]

The model:
[www.thingiverse.com]

Here is the resultant Gcode:
[www.dropbox.com]

Looking at the gcode, the lines do not appear to be the seam of the perimeter either.

Any ideas on what could be causing this?

Hi,

You should not print at layer height higher than 80% of the size of your nozzle. This means 0.3mm layer height should be a maximum for your nozzle.

And it looks like you extrude too much filament. When you ask your printer to extrude 50mm of filament, are you sure you get 50mm of filament? Or maybe your filament is a little big (use a calliper to verify)

Without looking at gcode, the line seems to be the seam of the perimeter. It is an option in slic3r to place the seam not aligned, if you would try it.

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Prusa i3 - e3d v5 - Gnu/Linux - Pronterface - Slic3r - Octoprint - Rpi - French

After a bit more experimenting this afternoon, I found the root cause, the interference fit between the printed pully and the stepper motor shaft would occasionally slip, causing some of the layer shifts, and once I solved that, I quickly managed to discover using the 0.5mm thin wall cube that I was extruding slightly too much filament (as you thought).

Now I'm getting lovely straight prints, and everything is looking so much better!

I will bring that layer height back down, and sit down and tune those e-steps a bit more :-) Just got to wait for some more filament to arrive.

Thanks for your thoughts.

Quote
kimented_
You should not print at layer height higher than 80% of the size of your nozzle. This means 0.3mm layer height should be a maximum for your nozzle.

He said he thought he had a .5mm nozzle. 80% of that would be .4mm, not .3mm.

Yes, my eyes saw 0.4mm nozzle

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Prusa i3 - e3d v5 - Gnu/Linux - Pronterface - Slic3r - Octoprint - Rpi - French