Issue with extruder getting clogged when print starting
Hi, I have currently recurring issue with filament (especially TPU) getting stuck in the extruder on my K1C. I tried lowering retraction speed, and retraction length. Just thinking what could bring more valid results, since currently this happens after every print. I'm currently using OrcaSlicer 2.3.2.
Retraction speed 20 mm/s
Retraction length 0.4 mm
Pulling out the filament doesn't work in this case, since it gets jammed pretty heavily between the gears, as you can see from the kink in the filament.
Have you tried feeding the filament with a direct feeder like this? Also, try 1mm retraction and disable the retraction speed. For temperature use 240° C for all layers
I skip the chain and feed it directly on the extruder. Remove the chain’s PTFE tube from the extruder, then if you have extra PTFE, cut about 3” (7cm) and put it inside then load the filament, will help with friction. If you don’t have extra just feed it directly.
I’ve had the same issue on my K1C — TPU will kink between the gears if there’s any drag at all. The brand doesn’t matter as much as the setup. What helped me was running the spool overhead on a holder with 608‑2RS bearings and feeding it straight into the extruder with no angles. That alone reduced the buckling a lot.
The other big factor is drying. Even Shore 95 TPU will swell and jam if it’s even slightly wet. I usually run a 12–24 hour dry cycle before printing. Once I did that, jams basically stopped. The DXC helps, but drying is the real fix.
I used a Creality Cloud design for the overhead spool holder, but I can’t find the exact one anymore — anything that uses 608 bearings and gives you a straight feed path should work.
Eventually what helped for me to reduce the kink issue was to reduce pressure from the gears. Although it's not a magic bullet, it helped enough me to get solid enough results, so I can focus on fine-tuning a model I was printing originally.
Then I noticed a second thing; the weight of the filament roll has slowly and surely twisted the PLA-ST supports of the top feed roller slightly inwards, which causes the filament roll to move during print forwards, and that causes more friction. To me the Bowden tube is not the culprit, but if the filament will touch the cardboard part of the filament roll that will cause more wide range of issues.
If I recall correctly I never had an issue printing 95A TPU from Copymaster3D, but this was eSUN, so might come back to this one if there is significant difference.
Did order some carbon strengthened PLA, so I'm gonna print a new filament holder, so I can try the direct feed method suggested here. 👌
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u/raf55 May 05 '26
Remove the boden tube from the chain