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Heat Creep & Under Extrusion

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Posted · Heat Creep & Under Extrusion

Hi there, 


I've been printing on and off with an UM3 for a little over a year now but I'm definitely still a casual user with little experience of 3D printing in general.


For the past year I've had very few problems, only a few failed prints here and there but recently I've started experiencing what I believe to be heat creep in the filament. I'm using Ultimaker PLA and the last few prints I've done have started out fine but after a few layers under extrusion begins due to the filament getting stuck in the bowden tube above the extruder. This is definitely due to the filament expanding above the extruder and getting stuck against the wall of the bowden tube. The feeder has been unable to counteract the increased friction and I've had to manually extract the filamnet from the bowden tube with a pair of pliers, which required a significant amount of force.


This image shows the filament being fatter in/close to the extruder (it's a little difficult to make out): 



This is how my prints look as a result of this under extrusion, oddly enough it appears the walls of the object print okay with the infill being the victim. This print was sliced using 100% infill:



And lastly here are the print settings I have been using, I use mostly default settings for all my prints. The only things I have changed are the print bed temperature (raised from 60 to 70 degrees for PLA), and the infill density. I'm using a 0.06mm layer height and 100% fan speed:



I've checked and cleaned both the feeder and the fan on the print head, the fan doesn't show any signs of inefficiency. The tension of the feeder has not been adjusted since getting the printer and it is only in the last couple of weeks I've started experiencing this issue. I've also cleaned the print nozzle several times with ultimaker cleaning filament and don't seem to be experiencing a blockage, like I said the print starts out fine and stops extruding a few layers in.


If anybody could offer some help I would greatly appreciate it.





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    Posted · Heat Creep & Under Extrusion

    Have you checked if the nozzle cooling fan is working? If not, this would give this phenomena.


    On an UM2 this is the little fan behind the nozzles; but I am not sure where it is on an UM3. Occasionally this fan may suck up hairs and strings of filament, and get stuck.


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    Posted · Heat Creep & Under Extrusion

    I’ve found that the side fans don’t activate during a print but they still work if I manually adjust their speed in the settings menu. I definitely haven’t adjusted any settings that could have caused this behaviour, and am wondering whether I’ll need to replace the fans?

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