Extruder Problem or what

Hi folks,

I have Prusa Mendel i3 (in the third picture)
Nozzle size 0.4, it has J-head hot end and an arduino with ramps.
Layer thickness 0.2
Printing with PLA 1.75

Everything was ok till I started to print Eiffel Tower. It does print well if it continuesly( for ex: if there were 2 owls on the heat bed, the printing quality will be like Eiffel tower) printing like Owl (in the picture), when I started to print Eiffel Tower, as you see on the pics there are strings and blobs. I think that it has an extruder problem. Is there any advice or suggestions?

Thank you

Edited 1 time(s). Last edit at 03/10/2014 08:59AM by hknky.

Are you using retraction? Have you played with retraction settings, such as speed and distance?

Yes, I have played with the settings but nothing changed.

I'm still rather new to the 3d printing world, but to me it looks kind of like it is changing layers too fast, causing the stringing and blobbing. The owl has a lot more filament per layer, meaning that the printer will take more time to complete one layer allowing the printed material to cool. If the layer prints too quickly, it will start to blob and come apart. There should be a setting in the slicing program you are using to set a minimum layer time, and you can also try to print 2-3 at a time to see if that helps, which will increase the amount of time per layer.