Sticky residue buildup in PTFE Tube - eviltoast

Trying to reduce the amount of constant maintenance the my ender 3 printers require and one of the biggest issues i’m having is a buildup of sticky residue inside the ptfe tube inside the hotend/ptfe tube. It’s not leaking as i visually inspect before cleaning and i can see where the tube connects and there’s a clear line and no visible signs of leakage. Usually some rubbing alcohol and a scrub brush will fix the issue for about 100hours of print time before needing to clean it again.

I’m wondering if i might need to reduce the flow rate on the printers or maybe i’m missing something. Running this with a direct drive extruder so the ptfe tube is pretty short and since the residue is building up inside the heater and nozzle too i don’t think that’s the issue.

Things i have tried:

  • less heat printing at 200 instead of 205 - marginal / no difference
  • printing speed turned down to 20mm/s - it takes longer for the buildup to become an issue but it also takes as long for the prints to complete
  • lowered retraction distance i thought the high retraction distance might be causing issues, while it made it better now i have stringing to deal with

EDIT: Added requested Photos -> https://imgur.com/a/XPKGI7D

  • rambos@lemmy.worldEnglish
    21·
    1 year ago

    Pic would help, but it seems like be your bowden tube is not seated properly. I had 5-6 mm retraction on 750 mm long bowden tube, and after I reduced play in push-fit connectors Im using <5 mm. If you need 7 mm to remove stringing its obvious sign that something is wrong. Make sure your bowden tube is not moving too much. You can try diferent retraction speed as well. Also, some filaments are just bad with stringing, especially wet petg. Sometimes I have to accept some amount of stringing to avoid using dangerous retraction distance.

    To fix play in bowden tube, you can cut 10 mm of tube on both ends. Your locking mechanism will bite fresh part of bowden tube. After you push the tube in the connector, lift collar with your nail, then push the tube even more, then press the collar in and pull it out with safety clip while still pushing bowden tube.

    It might be diferent on your hotend side, since your nozzle will push against bowden tube. If you have play there you will have bad time (leaking, clog, etc).

    Make sure you cut the tube perpendicular enough for good joint and tighten your nozzle when heated

    Edit: typo

    • zevrant@lemm.eeOPEnglish
      1·
      1 year ago

      the 7mm was a holdover from before i moved the extruder over to be mounted onto the x axisi don’t care so much about strining that’s simple to fix it’s the heatbreak clogging that’s the issue. As mentioned above, it’s not an issue with improper bowden seating as the residue is only inside the heatbreak and not where the ptfe tube sits. Also the ptfe tube is factory cut so definitely not the issue there. Nozzle does not push against the hotend tube as it sits on top of the heatbreak and does not go all the way through.

      I’m thinking probably heat creep but turning down the temps should have helped with that.

      there are pics please look at the imagur link.

      I cannot post the pictures directly as the site is broken and i get a 400 invalid json error.

      in case you didn’t notice the edit: https://imgur.com/a/XPKGI7D