Gaps on side of print

I am just started the tuning process for my SmartRap Core printer. Since the beginning I have been getting small gaps in the layers. Off hand it looks to me like an extrusion issue. I thought it might be skipping, but would a single skip leave that long of a gap?
Bowden extruder, 1.75mm Inland PLA, 200C, .3mm layer height, .4mm nozzle



Significantly, there are portions of the print that have no gaps for the entire veritical side! In this image you can see the gaps to the left, but around the curve to the right there are none.



I also having the issue that the very last thing the nozzles does when finishing the print is leaving a little mark on the top of the print, like the printer is signing an autograph! you can see it on the back right corner of this print:

It might be bowden related. Could it be that after retraction it resumes, but the pressure is not up yet, after printing some the pressure slowly recovers and prints normally. This can happen is retraction distance is set too high, the filament could get stuck in the cold end. The cold end cooling could be too vigorous, making it stick when only retracying a little bit.

Make sure the bowden tube doesn't move when it retracts. It should not move in its sockets.

What are the retraction speed, acceleration and distance settings?

As for the blob at the end, the overpressure in the bowden tube still pushes out filament while the hotend raises slowly. What I did was adding 5mm retraction to the end gcode in the slicer. You could also home the x axis instead of raising but that may leave a mark too.
G92 E0
G1 E-5 F9000

Quote
imqqmi
It might be bowden related. Could it be that after retraction it resumes, but the pressure is not up yet, after printing some the pressure slowly recovers and prints normally. This can happen is retraction distance is set too high, the filament could get stuck in the cold end. The cold end cooling could be too vigorous, making it stick when only retracying a little bit.

Make sure the bowden tube doesn't move when it retracts. It should not move in its sockets.

Ahh, that makes sense. My bowden is also too long and moves around quite a bit but I am fairly certain it isn't moving in the sockets. I'll check it though. Hadn't gotten there yet.

"What are the retraction speed, acceleration and distance settings?"

I haven't tinkered with these, set to the default SmartRapCore .ini file for Slic3r and configuration.h for Marlin:

retraction length: 4.5mm
retract acceleration: 3000
retraction speed: 40 mm/s

Quote
imqqmi
As for the blob at the end, the overpressure in the bowden tube still pushes out filament while the hotend raises slowly. What I did was adding 5mm retraction to the end gcode in the slicer. You could also home the x axis instead of raising but that may leave a mark too.
G92 E0
G1 E-5 F9000

Looks like the Bowden tube might be the source of "all" of my problems! I had previously added a z offset before homing in the end code. Did nothing. I'l try the retraction.

Thank you for the help. As long and drawn out as the whole process of buidling & tuning has been, I'm still thoroughly enjoying it!


Michael