filament keeps jamming in extruder hotend .. new build
Im pretty sure this is covered before but im extremely frustrated as I have yet to print ANYTHING and I just finished putting this together so I apologize in advance.
I was going through the initial setup process and just begin the calibration stage for the z offset .. i noticed the filament stop extruding about 1/4 the way through the process and nothing was coming out... i figure it had to be the filament adjuster not being tight enough or too tight … but it turns out the filament was jammed in the hotend …. no worries … i was able to pull it out and clear the jam. i start the process all over again and it happens again.... this time its really jammed in there..... i noticed that it got pinched by the extruder trying to feed it in so once again i tried to back it out by hand and this time the filament broke off and is jammed inside the pfte tube
ive already tried removing the fan ...heating up the hotend and manually trying to "push" the filament through with a small allen key .. nothing comes out ! i tried to remove the nozzle to see if i can grab the filament that way ..but the nozzle is EXTREMLY tight and my wrench was already "stripping" the nozzle head so i backed off before i damaged anything.
so what should i do? i started to take the whole extruder assembly apart thinking maybe the pfte tube is pinched somehow but first i need to get the filament unjammed.. again sorry about my frustrations as this is my second 3d printer that ive had problems... i tried to go "cheap" and bought a "knockoff" i3 and i had nothing but problems with it so spent more money and bought the original one thinking it would be a much better experience..
Re: filament keeps jamming in extruder hotend .. new build
Usually heating the nozzle to about 260 and letting it sit for a few minutes so the heat can climb into the heatbreak works.
Did you heat up before trying to take the nozzle out? If not, read the nozzle changing instructions on Prusa Knowledge base and try again using a socket that fits the nozzle.
You should be able to cut the filament just above the PTFE tube and remove the hotend assembly - again following the instructions for that step. If there is no filament above the PTFE tube you should definitely be able to remove the hotend with just a little effort.
Both ways, you need to be very careful not to break the heater or thermistor wires.
Bill
Tagaytay City, Philippines
Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor
Re: filament keeps jamming in extruder hotend .. new build
so in trying to remove the nozzle to try and clear the jam I broke my thermistor....I do have a spare I can use but I don't think the quality is the same.. I really think there is something going on with the tube inside the hotend… I cant belive the filament is that jammed that I couldn't even melt it out...
Re: filament keeps jamming in extruder hotend .. new build
The melt zone is only the last few mm of the hotend, below the top of the heater block, but if the melted filament gets pulled up above that by too long retraction or an unsuccessful unload or if you get heat creep from sitting too long without movement, it can expand and solidify in the fan cooled heatbreak where your reheating efforts don't reach.
It can be carefully drilled out from above once the whole hotend has been removed from the printer.
Bill
Tagaytay City, Philippines
Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor
Re: filament keeps jamming in extruder hotend .. new build
well that makes sense, because first time I cleared the jam the filament end looked like a "plunger" head when I pulled it out...what you described sounds exactly what happened. so going forward how do I avoid making the same mistake? again I didn't even print anything and it happened twice in a row during the setup process... I double checked the extruder gear and its properly aligned with the pfte tube. I used the filament that was shipped with the printer so don't think its that.
Re: filament keeps jamming in extruder hotend .. new build
I missed the fact that this was happening during initial setup.
That raises another cause, which is a badly assembled hotend. The law of averages says this must happen occasionally even from Prusa. When the hotend is assembled there should be no gap between the heatbreak and the nozzle. The assembly process has the nozzle fully inserted in the block and then partially backed out, then the heatbreak screwed in till it makes contact with the partially inserted nozzle and finally the nozzle tightened against the heatbreak. If that process was not followed correctly and a gap left between the heatbreak and nozzle, the additional volume of molten filament can then cause a problem even under normal retraction.
To minimise recurrence, follow the hotend assembly steps exactly, Make sure the PTFE tube at the top is correctly seated. If you increase retract length also increase speed to stretch molten filament before it cools. Never leave the printer sitting at printing temperatures for an extended time especially with filament loaded. Run a cleaning filament through the printer as part of your monthly maintenance, and add a dust filter to your filament path.
Bill
Tagaytay City, Philippines
Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor
Re: filament keeps jamming in extruder hotend .. new build
this is what the filament looked like the first time I was able to pull it out.. the second time is when it broke off
thanks for your input on this... I tried to warranty the hotend but alas they wont do it because its a kit. so I basically ordered it out of pocket. I ordered a complete new assembly and extra parts to rebuild this one to see exaclty what is going on.
Re: filament keeps jamming in extruder hotend .. new build
update
the problem still exists and the filament is still jamming in the cold during live z adjust... and this is while using a NEW hotend assembly
I dont want to do multiple posts on this topic so i have my symptoms listed on another thread
Re: filament keeps jamming in extruder hotend .. new build
I figured out the problem....the answer is on another thread.. feel free to lock this... thanks