K2 Extruder Jamming When Printing ABS or PETG

Flagship K Series Creality Flagship K2 Pro & K2
1

I am very frustrated and could use some help.

Until recently I’ve had good luck printing both ABS and PETG with my K2. Recently I have repeated failed when trying to print a particular part with either PETG or ABS. The failure is a jammed extruder. It appears that the material has softened to the point that if bulges out in the extruder gears and jams them. I have tried reducing the print temperature, increasing the print temperature, reducing the feed pressure, etc. Usually the first layer looks good. the 3rd or 4th layers starts looking rough and then the extruder jams. I have printed other, smaller, parts with ABS and PETG using the standard settings. The part that fails is a large part. The surface in contact with the hot bed takes up over 60% of the area of the bed. I can reliably print this part with PLA. Using PLA the part comes out great. However I want to make this part out of ABS.

I am not an experienced 3D printer. I have become an expert at disassembling the extruder, but that is pretty much the extent of my expertise.

I greatly appreciate any help!

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I’ve had this happen before, and it can be tricky to pin down. Since you already cooled the nozzle, you’re probably suspecting that this is heat creep, I would suspect that as well. When heat travels too far up the nozzle path, the filament softens before it reaches the melt zone, swells, and the extruder jams just like you described.

Here’s what I would check:

  1. Verify the thermal grease on the nozzle and heat break. Make sure there’s enough fresh grease to ensure solid contact with the heatsink.

  2. Confirm that the heatsink fan is running at full strength. If it’s weak or obstructed, the upper section of the nozzle assembly won’t stay cool enough, which is a common cause of heat creep.

  3. As a secondary check, look at chamber temperature. If the heatsink is getting warmer than expected, or the fan can’t keep up, heat creep becomes much more likely. I know ABS and PETG benefit from a warm chamber, but lowering it temporarily can help confirm the root cause.

Here are two articles that helped me understand the nature of the problem. You may find some insights.

https://all3dp.com/2/3d-printer-heat-creep/

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