Bulging Corners

Hello All;

I would greatly appreciate any help with this.

I have a Prusa I3. It has been working well, but I am looking to improve the quality of the prints. Any time my prints have a square corner, the corner bulges out, like there is too much plastic, just at the corner, or the printer is waiting at corners, although I do not notice that.

Here are the details. I print PLA at 190. I am using Cura 14.12.1, I print between 50 and 80mm, with a retraction of 1.5mm(speed 70). This corner bulging happens even when I print a cube that has no retraction. I just calibrated the extruder and it is NOT over extrusion, at least as far as I know. There are 2 pics here. The first pic, shows the corner bulge, and at this point my extruder was actually UNDER extruding by about 25%, as you can see the top infill is not complete. Then I calibrated the extruder, and the 2nd pic shows the top infill being complete. The extruder calibration did not seem to have any effect on the bulging corners, no better and no worse. The first pic is layer height of .3mm and the second pic is a layer height of .2mm. Neither seemed to have an impact on the corners.

These are my jerk settings; seem reasonable to me;
#define DEFAULT_XYJERK 20.0 // (mm/sec)
#define DEFAULT_ZJERK 0.4 // (mm/sec)
#define DEFAULT_EJERK 5.0 // (mm/sec)

I am not sure what is causing this. I have checked the mechanicals, and do not find any loose items or wobbles or anything else mechanical.

Pic 1 - sorry about quality, best cam I have - .3mm layer all corners are like this


Pic 2 - .2mm layer


Thanks!