I had to strip my extruder down for the first time this week and i have been printing ok since putting back together apart from the PTFE tube keeps coming out.
What have i done wrong ?
If you have pushed it in as far as it will reasonably go I do not think you have done anything wrong. I think you may have symptoms of a known problem and may need to do some hunting. The black fitting that the PTFE tube goes into has tiny little metal “teeth” in a ring all around the inside. They point in and down to catch and hold the PTFE tube. The red arrow shows one. When you push down the black upper ring (with the 4 on it on my printer) it bends or retracts these teeth away from the tube so you can remove the tube.
This ring of teeth is known to break apart and scatter bits of spring steel in extruder on occasion. This can cause jams and other forms of carnage. There are a number of fixes that involve printing new attachments for new pneumatic fittings to hold the tube. I printed some as spares and then used the device pictured in an attempt to protect the installed fitting from damage
All the fixes can be easily found on the Creality site online models in print 6. I think you can feed from the side spool into the printer to print the fixes to get everything running as normal again. The fix I used requires an undamaged hot end tube fitting. If yours is not holding you may need to print a new mount for a new fitting to get going now and contact Creality for a new part. If you have the detritus from the jam clearing, carefully check to see if there are any tiny shards of metal in there or anywhere else for that matter. You can try and get pictures of the teeth and see if they are still in place. I am no photographer and it took me 20 shots or so to get one were they were visible.
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Thank you for the very detailed reply, i will take a look at this.
Seconded. I’ve just had this problem but fortunately I already had a spare extruder housing sent by Creality from a previous complaint.
I say “this problem”, but I think I’ve been lucky. The teeth just seem to have stoped working rather than disintegrated. I note the end of the PTFE tube that enters the extruder was dark, almost burnt-looking, and deformed, pinched into an “hourglass” type shape at the end. Once I started getting the error that it had detached, it simply wouldn’t stay in the hole. I’ve taken some 6-8mm off the end with my side snips then spent some time making sure the hole is completely round.
Are the pneumatic fittings supposed to be replaceable? As I said I replaced my entire housing, but if it happens again surely there’s a way to replace just this fitting…?
Anyone?
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GreyArea, thank you so much for getting me off my a$$ to actually have a look at the condition of the tube end and giving it a needed circumcision with the pictured tool that guarantees a perpendicular cut.
.
247 hours and ~ 2.2 km of filament WITH a strain relief has the tube looking like this!
Getting it under my microscope it is not burnt it is almost worn through and that is NOT a lot of printing in my book. Even with a strain relief that attachment is a high wear and maintenance point. I would like to ask Creality to put configurable maintenance alarms in for this type of stuff.
Now to that fitting. Spring steel against a PTFE tube, we all know who is going to win that battle. Wiggle it about, push it against the upper glass and you have the basic design of a vibratory saw. A recipe for rapid wear. I believe the fitting is cast into the housing. I did buy some similar fittings but not having a spare housing, I do not want to sacrifice it until I have to.
My engineering concerns are as follows: Tube wear, finger fatigue on the fitting teeth causing failure and spring steel falling or being drawn into the extruder. I believe the installed teeth are the same as pictured and that disk of teeth is pressed into the fitting body. One breaks, the whole lot falls into the extruder. Guided and pulled there as the extruder consumes filament. I am going to be engineering the $41t out of this and make a completely new design to clamp the tube horizontally and then guide the tube/filament into the extruder vertically in such a way that there is zero play or vibration on the final fitting. Truth be told you guys do not count much in the realm of wife points and GT cars so this may take a week or more, sorry. It will be free to the community though. In the meantime I will be doing inspections often and circumcisions every 200 hours max, oy vey!
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I don’t know a lot of “stuff”…but I ask good questions, no?
I’ll take the pat on the back for starting this one, @Cannonman will do most (all!) of the work, so the applause is his!
Did I start this one ??? 
LOL to be fair, you did, but I think it was my comment about the state of the end of my PTFE tube that got @Cannonman’s gears whirring.
I’ll split it with you…one pat each?
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