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Just got a new printer which is direct drive and is using a cloned V6 hotend...


Using PLA everything is just fine, no problems and the prints turn out well. But 90% of the time I use TPU filament.


When using TPU, the filament loads into the extruder with no problem, the prints turn out really well, but after each print and The hotend Cools down it always gets clogged in the PTFE tubing inside the heatbreak in between the extruder and the nozzle. Constantly.... 


So in order to print again I need to disassemble the extruder and the hotend, remove the piece of PTFE tubing with the clogged TPU inside of it and replace it with a new piece of PTFE. After reassembly everything is fine again for one print but it clogs again if I let the hotend cool down before printing again!.!.! 


I'm not exactly sure how to prevent this from happening. Recently I've been cutting the TPU filament and loading a small piece of PLA in extruder until TPU is cleared from the hot end before allowing it to cool. This works just fine. It only happens when TPU is left inside the hotend when it cools down. 


On my other 3D printer this has happened before but only once in a great while, definitely not after every single print.


This happened immediately when I first purchased the printer with everything straight from the factory. So I'm positive it's not the way I have the hotend assembled. I make sure the PTFE tubing is all the way to the top of the heatbreak and the other end touching the nozzle.


I've tried to setting a smaller retraction and slower retraction in the slicer but doesn't help. 


If anybody has any advice I would greatly appreciate it.

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    Have you done a quick hot pull to yank out the TPU right at the end of the print?  If that works you could add a couple of lines to your machine settings End Gcode and do a long retraction to pull it out of the hot end.

    G92 E0

    G1 F2700 E-xx      ;where xx is the amount of retraction you need.

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