Circle not perfect

[Titeo]

I try to print several times the same circle, try to calibrate it the most i can but it's still not perfect. I try to adjust the tension of the belt, try to level the bed, try different temp and try to change the filament size in the software. But the circle still not perfect, can someone help me plz?? Thank you!
[img]http://i8.photobucket.com/albums/a37/Ti ... 258251.jpg[/img]

[Fiero2M6]

Is the circle's outline or infill the issue? You could try printing just the outline and see.

Have you callibrated your extruder? Check out this thread: http://forum.seemecnc.com/viewtopic.php?f=13&t=17

I'm assuming that your not trying to print at fast speeds during calibration.

[Polygonhell]

Usually if the outside of the circle is not round, it's backlash, usually because the belts aren't tight enough.
It's somewhat easier to tell which belt is "loose" if you take the picture either on the print bed, or mark where the XY axis were during the print.