Print is not properly laminated at certain height I have a Wanhao Duplicator i3.

I have done many excellent prints with this printer, and have first hand experience that it can do a pretty much flawless print.

But... Recently, I am experiencing weird results. My "flow" seems uneven. When laying down the first layer of the raft, I can see it looks like it "beads" in some places. Thin lines with little "beads" here and there (which seem to be in a constant pattern) i.e. -------()-----()-----()------()------ etc.

I initially thought, wet filament... But drying the filament had no noticeable effect. Further more, all my prints seem to be horribly laminated at a certain "height" of the print. This is really strange as it will print perfectly and only at a certain height, mess up about 5mm of layers (height wise), and then print great again. This seems to be a constant now.

I dont understand how/why this could happen, as the whole z-axis is on a linear spiral shaft. Unless there is a gcode issue somewhere that I am not aware off. I am using CURA as my slicer and I feel that even if there was an isnturuction hidden somewhere at a certain height, it would possibly effect a single layer, and not 5mm worth of layers.

Any ideas?

I have tried:

Different filament
Pushing flow % to 105 and 110% respectively
Cleaned extruder gears and print head
Oiled z-axis shafts

What baffles me, is the weird delamination (or rather lack of lamination) at a certain height. I have not measured this height exactly, but from guestimating, it looks like roughly the same height on every print where the issue is visible (about 3/4 up in the attached image). My support structures are also VERY messy, whilst they were very precise and perfect previously.



Thanks
This looks like a heating or retraction issue. I also have a Di3, and I encountered a similar problem a while ago. I have found that leveling the bed very well and making sure the z-axis is aligned fixes most problems with this machine. Re-calibrate your printer and try out a different slicer. This link from the 3D Printer Wiki is very useful.