PLA Filament Jam in PTFE Tube
Morning all. Frustration is mounting and while I could guess at the problem I would love some help. Just put in a new PTFE tube in my Mk3S only to have the same issue recur. Having not yet disassembled the extruder to verify, cause that's a joy and I'll need to order another tube(s), I have verified that I cannot unload the filament; it appears jammed. Looking at the old tube I see a glob of filament a quarter inch from the exit end which appears melted into a plug which prevented both extrusion and normal removal/unload. The tube itself, aside from being plugged appears normal. The print I was working on appears normal, except unfinished, though the printing time elapsed is correct for completion. So the printer finished the job even after filament stopped extruding. So maybe a hot end fan issue. Ideas? The other scenario simply blames the PLA used, a Ziro translucent blue, for quality issues. This job is the first extensive use of this product.
On a side issue, as the PTFE tube I removed appears perfectly serviceable outside of the filament plug, and there will be a delay in getting another, is it possible to clear the tube and/or wise to reuse it? The issue is the delay not the expense.
I have now removed the tube (quite adept at the process now) - identical issue. Did note the hot end fan was working fine when I heated the nozzle to clear anything out. I believe the extruder gears are working as well as the filament I removed from the extruder showed scrape marks I believe occurred once the tube jammed and the gears simply ground against the filament. The filament was not going to be pushed out of the tube by an allen wrench but with careful use of a heat gun I was able to extract it. The tube appears to be serviceable and I confirmed so sliding a piece of filament through it. I am still at a loss as how to proceed. I will reassemble and take care to adjust everything carefully and maybe try different filament. I really don't want anymore experience changing PTFE tubes.
Currently I have the hot end hanging on its wires. It has been suggested that heat creep might be the issue due to possibly damaged hot end components. Short of obvious visual damage to the heater block, heat sink, or heat break how can you diagnose each components status? And I assume disassembly would require application of new thermal paste. I should admit I just built this from the kit about two months ago and have only been printing sporadically. Furthermore my technical prowess is not above average though I'm willing to tackle projects requiring steep learning curves and I've learned much about the hot end in the last few hours.
I have ordered all hot end parts as a backup should they be needed now or in the future but I would love some instruction on diagnosing the problem so as to avoid more disassembly/assembly practice.
Sounds like the heater block is intermittent. How old is it? Have you tried reseating (unplug, replug) the wires that go to the print head in the Einsy case? Maintenance procedures call for reseating all connections about every 100 hours.
Did you lock the ptfe tube into position?
When you insert the tube you need to push it completely home, then while holding it pull the black clip away to lock it in position.
Check step 8
I would also be tempted to check the heat break is installed correctly and has heat paste applied. Might be worth disassembling the hotend, applying fresh heatpaste. Its always possible its not been assembled correctly.
If the nozzle has ever been replaced, especially if following the Prusa guide and not the E3D guide, there's a fair chance the heat break has moved in the heater block. A full disassemble and follow the E3D-V6 guide when putting it back together is probably a good next step.
And good high temp thermal compound is required. 250c is a lot hotter than the 90c cpus get to.
Thanks for all the feedback. Thought it might be best to reply to all at once. First I assembled the printer about 2 months ago; so not old. Maybe 50 hours of printing to this point. I will reseat the wires in the Einsy. Likewise I will replace the PTFE tube and make sure it is properly secure. After that I think I will attempt another print. If the jam recurs I will disassemble the hot end, inspect it carefully and at a minimum repaste the heatbreak. By the way is there any secret to that process? Like cleaning off old paste. I'm tempted to disassemble the heater block and clean it up or replace it as it does carry scars from my learning adventures on early prints such as prints breaking free and reassembling as a large plastic ball around and on the heater block and nozzle. Is this a wise or necessary move? I've also secured a replacement should that prove necessary. I have the same question about the nozzle. Another aside concerning nozzle replacement. I read somewhere that the process required heating the nozzle first. Somewhere else I didn't see that requirement. Comments? On another forum a comment was made that the same problem, filament jammed in PTFE tube, was resolved by adding additional fan cooling across the filament stepper as it was heating up during long prints and assumedly transferring the heat to the hot end assembly. Is this a likely problem and reasonable solution?
So I await your input although I will not be colocated with my printer for a couple weeks as life has chosen to interfere but will weigh in with results or plead additional help at the first opportunity. Thanks to everyone!
Another set of insturctions:
As stated in another thread - the Matter Hackers procedure is flawed and wrong.