irregular steps and gaps between filaments on x axis

I am a noob and have done about 8 prints in PLA.

I have been having gaps in the filament on the X axis for no obvious reason.

On the worst pink square i have y-borders all equals to 3 millimeters with no gaps, and the middle x border is 4mm instead of 3.

What can cause that kind of irregularity?

Edited 5 time(s). Last edit at 03/20/2015 08:51AM by skynetprinter.

A loose belt, wobbly hot end, or a not tightened set screw (check all belts and pulleys). There can also be a problem with whatever slicing program you are using. Try a different release of that slicing software or a different slicer all together.

Thanks for the suggestions.

What tests can i do please, some calibration models to find if the motor or firmware or calibration is faulty? the error is .5mm / 500 steps range. i think i'll print some 2d stairs for a flea and see how many steps are contrary to ISO flea standards.

The belt is taught, the ball bearings are soft and yielding, the extruder is well fixed and tight.

it's a robot precision kind of error, it has to be the motor or the firmware. the G-Code is ok.

I did a test with some step shapes. It's a complete mystery, some of the widths are normal, and some are displaced, all the form should be made of 1.6mm widths.

Edited 3 time(s). Last edit at 03/20/2015 09:10AM by skynetprinter.

I ran a G-Code that worked in the first week and now it's messed up.
I think my motor is faulty because the bearings, fan and extruder all seem fine.


Edited 1 time(s). Last edit at 03/21/2015 01:01AM by skynetprinter.

I have fixed it in the end.

Switched the X and Y motors around and in the process discovered that the x drive cog had become loose and was able to rotate backwards and forwards by .5 millimeters, so that when it travelled to the left it was .5 millimeters away from when it travelled backwards again to the right, thereby giving very regular and inaccurate results.

Thanks everyone, hope this thread is useful to others with the same issue.