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.
I have tried:
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.
Looks like either a retraction problem, or a heat setting issue. There could also be some buildup in your nozzle, but more than likely it's one of the first two.
Louis van Tonder Correct answer6 years ago
Thanks to all the replies. Whilst all of them may be valid in some scenarios, my case seemed to have been a combination of things, that relates to most of the replies here.
I had my spool holder on the side of the machine, and I noticed some friction as the filament feeded over the "arm" on top of the printer into the extruder. I sat and looked at this for a while, and it seemed apparent that as the extruder moves up, the angle of the filament over the "guide arm" on top changes to a more severe bend. This may have been why it always battles to extrude nicely at a certain height, and then maybe recoveres after that to an extent. (SO yes, under extrusion may have been the issue)
I have now moved the filament to on top of the printer to feed straight down. I have also slowed down the travel to about half of what it was (40 now, was 60). I also dropped the infill speed a bit as that was also a mess most of the times.
So far I have had excellent results! I am not sure if its the travel speed drop or the extruder feed that helped the most, but I am a happy chappie again. (So far).
Thanks for all the input. It really made me re-look at all of this from a different view.
I have experienced similar issues with my cartesian printer. In my case, the force required to pull the filament from the spool was too great - on one occasion, the spool spindle was stuck so badly that the holder gave way and the spool crashed into the printer. After several iterations of spool holders, the problem is now gone for good.
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Content dated before 7/24/2021 11:53 AM
Mikhail Z 6 years ago
Looks more like retraction issue. Need more data: 1) print retraction settings 2) heatbreak radiator temperature (should not be more than warm) 3) can you hear extruder motor clicks during the print?