Missing filament on some parts at random events

[urosv 0]

Hi guys. I just got brand new UM2 and started to using it with PLA. After a few prints and overall happiness i tried to use white ABS. It is noticeable harder so first push of filament in filament pusher area behind UM2 was noticeably harder. Then i tried to print some stuff but overall prints were bad looked and not solid at some thin areas. Then i also tried a Flex PLA and again no luck (maybe just settings and tuning). And now the problem. I finally replaced the filament back to PLA and i noticed that motor that fills the filament inside was randomly cogged and make small "kkk" noise, you guys i think call this retraction if im correct (at first usage of PLA there was not any of this sounds), so now always as this occur there is a lack of filament in print at this point for another few mm? Tried almost everything and also with a different Cura versions, retraction ON/OFF, distances etc. Heating from 200 to 240, silament delivery from 50 to 200%, speed from 20 to 150mm/s etc... Also tried to tighten/loosen the strength screw for cogwheel of the motor. On this picture it is the best possible way to print everything else was worse !

Every help is appreciated...

 

[illuminarti 18]

Can't see the picture.

No, retraction is the intentional pulling-back of the the filament, prior moving to a different part of the print. That reduces the chance of oozing and stringing of filament lines across the print. I think the sound you are hearing sounds more like the extruder motor clicking back as it skips steps, because it isn't able to extrude properly.

Most likely, you have some partly-melted ABS stuck in the hot end. You need to heat the head up to 250 or 260 degrees, and the use the 'move material' menu option to try and advance the filament through the print head until all the ABS is flushed out.

 

[gr5 2,189]

It may take 5 minutes of extruding before most of the ABS is out. It is very difficult to switch from ABS to PLA - you have to clean the print head good.

 

[urosv 0]

Hi Guys, and thanks for your feedback and help. Illuminarti has the point saying extruder motor clicking back as it skips steps I updated the picture in first post what is the result of this. I already cleaned and heated the nozzle to 260 and also after that I printed a lot of stuff just to get knowledge of settings in Cura and my findings are that 95% of failed printing is due bad settings in gcode. I did not print again the problematic thing but rather I projected my own with some other preferences to overcome holes and skipping steps.

Further more I'm attaching another image to be looked and if you give me feedback what could be wrong...

Settings are here (profile2.ini)

 

[gr5 2,189]

That looks exactly like normal underextrusion. Try printing slower. Here are photos of underextrusion:

(post #1 gray picture, post #2 also):

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/