Nozzle clogs mid-print
I recently assembled and calibrated a new i3 MK2. I got several excellent prints, but I've recently run into a problem where the nozzle clogs after an hour or two of use. The extruder motor will start to skip and no filament comes out. If I catch it right away, I can push some filament through manually with a bit of force, the clog clears, and it will work fine for a bit until it clogs again. If I don't catch it right away, the clog is bad enough that cleaning it is an ordeal. I thought maybe my Z axis live adjust was too low, so I moved the z axis up several inches, and manually activated the extruder motor (through the settings menu), but the extruder motor continued to skip. Here's what I've tried so far:
but I did this because I damaged the thermistor wires when removing the nozzle the first time. I thought for sure this would resolve the issue, but still have the same problem.
The only other thing I can think of is when this problem started, I also began having difficultly loading filament. The filament pushes slightly away from the pulley on the extruder motor and the edge of the filament catches on the PTFE tube. If I'm careful to straighten a couple of inches of filament, cut a steep angle, and ensure the pointy side of the angle is to the center, the filament will load. I did not have to do all of this when I first started using the printer.
Sorry for such a long post. Just want to provide as much detail as possible. I'm not sure what might be important and what's not. Does anyone have any suggestions as to what I should look at next? I'm considering replacing the stock extruder with a titan aero, but I don't want to replace the extruder and continue running into the same clogging issues.
Re: Nozzle clogs mid-print
I recently assembled and calibrated a new i3 MK2.
[*]Played with the tension on the idler tension screws. I'm not really sure how tight these should be. Is it normal to cut thin grooves into the filament as it loads? While we're on that part of the assembly, I cleaned out pulley on the extruder motor. The idler bearing spins.
It sounds like you might have those tension screws too tight. If they deform the filament too much, it will cause the filament to catch in the extruder and jam.
They should be looser than was intuitive to me. I keep mine 14mm out from the body without a filament in. It expands when a filament is in. This is just engaging the spring.
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…
Re: Nozzle clogs mid-print
hi tj
it sounds like a frustrating problem
the simple answer is only to print for less than a couple of hours !! sorry couldn't resist it
have you checked the wiring - are the thermisters the right way round - you say that you have had thermal runaway - is this after a few hours of printing
the thing which worries me is the fan being on when on the first layer it should be off
is it connected to the right connector?
the numbers run from 0 to 255 ( pwm from 0 = off to 255 fully on)
so 0 will be off, but the fan will only come on when the numbers reach 50 to 100
can you verify that this is controllable by using the tune menu when doing a test print .
turn the fan control up and you should hear the fan speed increase
likewise turn it down and it should reduce.
if your printer is having difficulty loading the filament with pushing the filament away from the pulley then the motor will need more power to force the filament just into the ptfe tubing.
can you turn up the current on the controller - it may only need a small adjustment - you don't want to overcurrent the stepper motor.
i am wondering whether you have any cooling over the electronics?
can you feel the extruder driver getting hotter than the others?
you will cut grooves into the filament to assist pushing the fialment into the hot end.
once in the hot end the filament softens and seals the tubing forming a plunger
in front of the plunger the filament will become molten and be forced out of the nozzle.
if the seal becomes too long your stepper motor may not be able to push it into the tubing
do you hear any clicking noises when it stops ?
can you verify that the extruder gear is still going round
when you clean the nozzle next try using a little bit of metal polish and a toothpick to polish the insides of the nozzle.
hopefully some of this will give you more to check and the problem can be resolved
there is nothing more frustrating than a problem that is only there after a long time period - you think you have cleared it and it comes back just that little bit later !!!!
let us know what happens if you try some of these things
phil
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Re: Nozzle clogs mid-print
...The fan is set to be off during the first layer, but I noticed that it was running anyways....
which fan are you talking about ?
there are two fans at the extruder. one at the left side of the extruder with the task to cool down the coldend (the part of the extruder above the heatbreak) below 53°C. this fan should start immediately after the nozzle temperature reaches 50°C and should stay on until the print is done and the nozzle temperature drops again below the 50°C threshold.
the other fan, mounted in front of the extruder, is the print-fan. it's task is to cool down the freshly extruded filament so that it solidifies as soon as possible. this fan could be controled through the settings menu and within the gcode with a value between 0 and 255. usually it starts to spin above approximately 50.
for the functionality of the extruder the first fan is essentially. if this fan is blocked or not starting, you'll not only get a clooged extruder by certainty you may damage your complete extruder body severely, because the coldend then heats up and may melt the extruder body (which is only a printed part itself).
may it be that you mixed up both fans ?
dem inscheniör is' nix zu schwör...
Re: Nozzle clogs mid-print
I am having a very similar problem. I am curious to know if you got it fixed.
Re: Nozzle clogs mid-print
I've got the same problem...
No solution found 🙁
Re: Nozzle clogs mid-print
There are plenty of possible solutions here on the forum. Here's a few:
Retraction settings
Badly assembled extruder
Extruder fan fail
Filament feed problems
Dust on filament
Damaged PTFE tubing
Blocked nozzle
Damaged heat break
Filament drive pulley loose (grub screw) or mis-aligned
Filament tension wrong (try less tension first)
Any one of the above (and I am sure the list is not exhaustive) can cause blockages and solutions to all can be found using the forum search.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Nozzle clogs mid-print
I am also having the same issues and have done similar troubleshooting methods. A larger retraction distance seemed to help, but I still get a blob of filament that is too large to pull through the little metal tubing and then gets stuck. I have wasted numerous prints and so much material. If anyone has a solution please help.
Re: Nozzle clogs mid-print
Hello,
I am also having the same issue but ONLY with PLA. ABS and PETG are working fine, not PLA (tried 3 different PLA filament, 2 ABS and 2 PETG). Strange behaviour, if it was an assembly issue, why are ABS and PETG working ?
Can you ppl state what kind of filament is causing issue for you ?
Re: Nozzle clogs mid-print
I've been having the same problem. In the past, the issue was caused by not having the PTFE tube tight against the heatbreak inside the hotend, but even after making double sure it was tight and with a new PTFE tube. I'm still having issues. At first I thought it was my retraction settings, but even with retraction disabled, I am still having extruder skips after about 1/2 hour of printing. As others have complained, the first few layers go down no problem but then the extruder starts skipping. Manually forcing the filament in seems to fix it for a few minutes only.
I know this is an old thread, but I was wondering if anyone had a solution.
Re: Nozzle clogs mid-print
I am having similar issues. A more up to date string of responses can be found here: https://shop.prusa3d.com/forum/how-do-i-print-this-printing-help--f63/problems-printing-pure-pet-after-switching-from-pl-t19177.html#p92201
Re: Nozzle clogs mid-print
I just want to share my bit about my issues and how I resolved them. For a while, I would either have to leave my enclosure open with the AC running, or I would have to make sure prints didn't run for a long time. Consistently I would have jams at near similar layer heights. For reference, this only occured with PLA. PETG and other materials that heated at a higher melting point did not experience this issues nearly as frequent.
What did I do to fix this? Well I did a few things. To preface this, I read through a lot of forums and tried a lot of work arounds without modding the printer. Then I started by replacing the PFTE tubing, insuring to have the end rounder off as described in the manual. Next, I disabled the filament sensor which unfortunately did not fix my issue as it seemed to fix somes.
What ultimately mitigated my issue was a combination of 2 things. The first thing I noticed was that the filament sensor would get very hot even to the touch. Sure, disabling would have fixed the issue completely, but I wanted the functionality. So I moved the 5v fan that is included in the printer to the top opening (originally mounted with zip ties - I am currently working on a part so this can be removed and reinstalled easier). Secondly, I installed a 12v Noctua fan where the old 5v fan on the left side was. I wired it like so: Direct connection to the 24v rail, which then was installed into a voltage stepper which stepped down the voltage to 12v, and then connected to the fan. This allowed for more air to flow over the "heat sink" (I am calling it a heat sink since the actual name for the tube is escaping me at the moment) which ultimately eliminated the heat creap issue.
Ever since doing these 2 (possibly 3, the PFTE tube might have contributed but I still experienced issues after that alone) simple modifications, I can report that I have had many successful prints that were not working prior. I used the same gcode files and everything, so these 2/3 things definitely helped a lot. Hopefully this will help someone else out, because believe me I was very frustrated with this.