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Under extrusion and jammed filament

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I have started this part 4 times now and it does the same thing every time. The brim goes down like a champ and then when it starts the criss-cross pattern I start to see small bits of under extrusion. The spots get progressively worse until extrusion stops all together. I unload the filament, if I am lucky. Most of the time I have to take the extruder apart and reload. You can see in the other 3 attached pictures what I end up with. The hot end is always a little fatter with a bulge right at the spot where the filament leaves the bowden tube. The next two pictures show the filament where the extruder fails to feed but then does okay for a bit (the out of focus picture) and the last picture is of the spot it leaves when it gets stuck for good.


I have cleaned the extruder, changed filament (currently have a brand new role on), checked my level, checked the tension on the extruder feed wheel and tried leaving the door open and closed. I get the same result every time. The last two parts of similar size came out just fine. 


I also attached the profile I am using. Any help would be great. This part not printing is holding up a big project.







PLA 09102018 1.5mm.curaprofile

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Have you tried printing with a different PrintCore if you have one? That's a fairly easy way to remove the Core from the list of potential culprits. 


When you do a coldpull, do you follow Ultimakers guide on how to properly perform it? It's important that it's done correctly to work as intended, and some times you'll need to do I several times to clear the blockage. 

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There are many possible causes.  The two most likely where it prints first layer fine but not second layer are:

1) 3rd head fan broken.  Is this Um3 or Um2?  Either way there is a 3rd fan in the head - there are the side 2 fans but there is a 3rd fan.  That must be spinning or you get this exact scenario - stops extruding after a while.


2) printing too fast.  The first layer prints slower - at 20mm/sec.  Try slowing down the second layer to 20mm/sec to see if that makes a difference.  You should be able to print much faster than 20mm/sec but if you can slow it down and it starts printing fine again that's an important piece of information for us here on the forum.  You can adjust the speed in the TUNE menu (for both UM2 and UM3).


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Note that the 3rd fan (on UM2 and UM3 and S5) doesn't spin up typically until temperature of the head gets above around 40 to 60C.


If it's a UM2 the most common failure for the 3rd fan is in the cable connectors just above the print head.  Not the fan itself.  It's easy to slide up the black netting and jiggle it until the fan starts spinning and then you can typically fix the connector.


If it's a UM3 the most common failure for the 3rd fan is the connector inside on the top of the head.  It's very very easy to fix.  Remove the very long screws on the rear of the head (just 2 screws) and the rear half of the top plate comes off easily and the rest of the head stays together (don't loosen the front 2 screws, lol).  Then you can see the cable and connector and push it back in.  If it was loose then add some tape for a shim around the cable so when you put it back together it's held more tightly and won't come loose again.


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