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I'm struggling with an upgrade I made to my Creality CR-10. I upgraded the extruder to an E3D V6 hotend. The extruder mount and cooling fans are installed and working, however, I'm doing something wrong with installing the bowden tube into the hotend. Inevitably after I print a few layers, the extruder jambs and the issue is always the same: the bowden tube has backed itself out a few tenths of a millimeter, and the filament has mushroomed into the vacant space and hardened so that the filament cannot go forward or backwards.

I've tried several things to fix the issue including:

  • Trying various pneumatic fittings from various suppliers
  • Recutting the end of the bowden tube to attempt to make it more flush
  • Replacing the bowden tube
  • Three different E3D heat-breaks from different supplier
  • Various ways of inserting the bowden tube including: pushing it after the fitting was screwed in, pushing it into a fitting that was back out a couple turns and then screwing the fitting in

The only thing that has (partially) worked was when I would ductape and hot-glue the bowden tube into the fitting so it couldn't back out. However, since I'm still tweaking things, I inevitably have to disassemble things and I'm back to square one.

I'm trying to figure out what mistake I am making to keep causing this issue. As an example, originally I used the pneumatic fittings wrong and thought I was supposed to pull the plastic part out to release the tube, rather than simply pushing it in to release the tube. (Needless to say, I wrecked a lot of fittings that way.)

What else might I be doing wrong to keep causing this issue? What are other culprits to this issue happening repeatedly? Are there firmware settings that may help (or be aggravating the issue)?

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    $\begingroup$ do you have a genuine or a clone hotend? Do you print PLA? $\endgroup$ – Trish Feb 28 at 21:53
  • $\begingroup$ Clone. I've got 3-4 amongst my printers and have tried swapping various parts (like the heat break) so see if it makes a difference. (It hasn't) The only unique thing about this setup is that it uses a bowden tube rather than being direct drive. $\endgroup$ – SvdSinner Mar 1 at 14:40
  • $\begingroup$ In that case: the coldend and the heater block are rarely a problem, but I suggest to get a couple embedded bowden couplings and a genuine heatbreak. badly machined heatbreaks (without the notch) and bad couplings cause lot of trouble, the expense is worth it at times (like with tubing). Also, add thermal transfer paste between heatbreak and coolend, and hot tighten it. $\endgroup$ – Trish Mar 1 at 14:46
  • $\begingroup$ Just wanted to follow up with results. Tired of this issue I wanted to nuke this issue from orbit. Firstly, I bought a new E36V6 extruder with a bowden tube pre-installed. ( I wanted to be 100% sure that I wasn't doing something else silly.) The new extruder took only 3 small prints to start showing this issue again, so that wasn't it. From there, I fashioned a clip as suggested below with some metal wire I had. Since I added the clip, I've done 5 prints with no issues related to the tube backing out. If the problem reoccurs, I will update this thread. $\endgroup$ – SvdSinner Mar 13 at 19:01
  • $\begingroup$ That suspiciously sounds like the clip, yes. I strongly suggest to try to get a genuine fixing kit, even if it costs more. $\endgroup$ – Trish Mar 13 at 19:08
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You may need to secure the pneumatic coupling in the closed position with a small plastic clip (which should be supplied with the hot end).

Pneumatic coupling with retaining clip

You can print your own, providing that your printer will work for long enough (a paper clip might do the trick):

Thingiverse: Bowden Tube Clip v3

Addendum:

Some pneumatic couplers are sprung, so that you have to depress the coupling ring in order to release the tubing. In this case, no clip is usually required. Other pneumatic couplers (such as the one on an E3D V6) are unsprung. This makes it easier to secure and release the tube using the supplied clip. The disadvantage is that you may lose the clip. Sprung couplers sometimes lose their springiness, in which case a clip can be used to secure them in the closed position

It's "swings and roundabouts", really. You can to choose between the awkwardness of sprung couplers, or the risk of losing a clip. Either way, print some spare clips. You may need them one day.

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    $\begingroup$ Thee clips are often not used as they are usually not necessary, but in some cases you can't print without them, I have the same experiences with a certain printer I use, good call! $\endgroup$ – 0scar Mar 1 at 8:58
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    $\begingroup$ @0scar Agreed. The PC4-M6 coupler on my feeder does not need a clip, but the coupler on my (genuine) E3D V6 hot end does (as in the photo). Answer edited. $\endgroup$ – Mick Mar 1 at 9:02
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    $\begingroup$ This solved the issue for me! Thank you. Is there any understanding of what triggers this issue? Many people have run bowden tubes without a clip successfully, but it was obviously critical on my setup. I'm curious what factors may be at play here. $\endgroup$ – SvdSinner Mar 13 at 19:05
  • $\begingroup$ @SvdSinner Answer edited. $\endgroup$ – Mick Mar 13 at 20:20
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This sounds more like a problem with heat creep. When you installed the new hotend, did you reuse the old cooling solution? You might need more heatblock insulation and / or cooling power.

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  • $\begingroup$ heatcreep does not loosen the tube. $\endgroup$ – Trish Mar 1 at 10:27
  • $\begingroup$ That is not a fact. Melted filament above the throat does all sorts of terrible things. The questions asked are still valid troubleshooting steps as the pieces changed do require reworking the cooling system. $\endgroup$ – silver Mar 1 at 17:24
  • $\begingroup$ Then explain how heatcreep in an e3D V6 should result in the couplers no longer holding the bowden tube. "terrible things" are mainly clogs $\endgroup$ – Trish Mar 1 at 18:16
  • $\begingroup$ Changed my mind. No. $\endgroup$ – silver Mar 1 at 21:02

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