Extruder completely stuck, heat didn't fix it
Hi,
I have a new i3 MK2. I have done a few prints on it so far, all with the included PLA. My first few prints came out OK, but then it started having trouble extruding where groups of layers came out with too little filament. I tried loosening the tension on the filament feeder, and that seemed to help at first. Then one or two prints later, when it started, almost nothing came out of the extruder. I canceled the print and tried feeding through filament by hand, and nothing would feed through.
I went through troubleshooting on the Prusa chat by trying to clear out the block with thin wire in the nozzle, and hand-feeding the filament at temperatures all the way from 210 to 295, but no filament will come out the nozzle.
When I feed in filament by hand (with the idler door open), the tip of the filament will go to about the middle of the round metal finned heatsink, and stop dead. It feels like it's hitting a hard, solid surface.
I've only had the printer a couple weeks, this is pretty discouraging. What can I do to fix this?
Re: Extruder completely stuck, heat didn't fix it
What happens when you insert the needle through the nozzle when it's heated to PLA temps (210C)?
Does it hit something hard or is it able to pass through easily?
Re: Extruder completely stuck, heat didn't fix it
Also, are there any signs of plastic leaking out from the hot end anywhere. Could be a plug from a loose connection between the heatsink and barrel.
Re: Extruder completely stuck, heat didn't fix it
No leaks anywhere. A little bit of plastic was weakly coming out of the nozzle right after it jammed, now nothing comes out anywhere, and the filament I try to feed in doesn't even melt. It just hits something hard and is completely intact when I remove it.
I didn't get a needle with my printer for some reason, but I had a .33mm resistor lead which on recommendation from chat support I inserted into the nozzle at 210. It goes in about 2.5 CM before hitting something hard.
Re: Extruder completely stuck, heat didn't fix it
David
We have had this problem reported a few times on here with the V6 extruder; seems that it may be caused by the retraction settings being too high (but that is only one of many possible causes).
Most users have ended up having to displantly the extruder, but if you do choose to do this, take care and read the posts of other users.
And ensure you are running the latest version of firmware and drivers.
Perter
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: Extruder completely stuck, heat didn't fix it
Most users have ended up having to displantly the extruder,
Hi Peter,
Do you mean disassemble the extruder? I am running the latest firmware and drivers, and only used the slicer retraction settings provided on this website for the i3 MK2.
I found the threads below which seem to be the same issue. I would like to get confirmation from someone at Prusa Research before I take it apart, though. I'm concerned about breaking something.
http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/filament-stuck-in-heatbreak-t1059.html
http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/stuck-filament-t984-s10.html
http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/more-stuck-filament--t1016.html
Re: Extruder completely stuck, heat didn't fix it
I spoke with Dan from Prusa Research support. After showing him this thread, we tried brute force to clear out the extruder, but that didn't work, so he walked me through taking the extruder assembly apart.
We managed to find the blockage, but he recommended that I come here for suggestions of how to clear it. Any suggestions? Photos below.
Disassembly:
Heatsink removed:
Blockage in the heatbreak:
Any suggestions would be appreciated.
Re: Extruder completely stuck, heat didn't fix it
If you can now heat up the nozzle safely (holding the heater block securely with some pliers and not moving things around much), then you should be able to push the molten PLA in & clear this clog ?
To be really safe, I would keep some strong cardboard over the heatbed during the process - in case anything happens accidentally, I won't want the heatbed to be impacted.
PS: I am a newbie, please try at your own risk !
Re: Extruder completely stuck, heat didn't fix it
David
Shree is correct in that heating may now work.
I would have done things slightly different; removed the nozzle as a first stage (seems that you still have nozzle attached) and then run a 2mm drill down the barrel (very slowly!).
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: Extruder completely stuck, heat didn't fix it
Shree, PJR,
I heated up the nozzle/heat block/heatbreak assembly in its disassembled state, and was able to push PLA filament through the nozzle, presumably because without the heatsink on it, the heatbreak was hot enough to melt PLA. Pushing PLA through the hot heatbreak just left me in the same spot as before, though; whenever I stopped pushing through the filmanent, the plastic in the heatbreak solidified, so it was just jammed with new filament.
I then tried pushing the filament out of the heatbreak with a ~1.6mm metal rod. That left the heatbreak mostly free of filament, but the walls of the heatbreak are still coated with PLA, and this makes it very difficult to push filament through the heatbreak with it at a normal temperature (heatsink on) because of the extra friction/reduced diameter.
So it extrudes, but only when the heatbreak is hot. How can I clean the heatbreak out fully so that it's not grabbing or blocking the filament when it's cool? Or do I need a new heatbreak?
Re: Extruder completely stuck, heat didn't fix it
David
There is a temperature (between 90 and 120 degrees for PLA) where it is possible to pull the filament out in its entirety.
Heat it up to 200/210 degrees, push some filament down so that you get quite a lot out the nozzle, then turn the heat down to 100 degrees.
Hold the heat block with large pliers and the filament with small pliers. Then quickly yank on the small pliers and the filament should come right out.
If you don't get it all out, reduce temp by 10 degrees and try again.
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: Extruder completely stuck, heat didn't fix it
Thanks, PJR, for that procedure. I had been trying to do something similar, but without the knowledge of the 90-120 temperature range, with no luck. I tried again per your instructions and got a good chunk of plastic out all at once. It looks likely that it's all been cleared out, but I'm afraid I'll get it jammed again if I test it without the extruder fully assembled.
The thick part at the top is where plastic pooled at the top of the heatbreak. I can now look down the heatbreak and see light from the end of the nozzle, which is definitely good.
With everything cold now, the heatsink on and PTFE tubing inserted all the way, I can insert the filament down to about half way into the heat block with low resistance overall. There is a point, around where it reaches the top of the heat block, though, where the filament catches on a small ledge and needs a firm push to get it past.
Do you think I got everything out? Should this ledge be a concern?
Re: Extruder completely stuck, heat didn't fix it
David
My guess is that the PTFE tube is not quite square at the lower end or it is not going in all the way.
Take out the ptfe tube and check the end; maybe even turn it around. Oush it dwn and lock firmly in place.
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: Extruder completely stuck, heat didn't fix it
David
My guess is that the PTFE tube is not quite square at the lower end or it is not going in all the way.
Take out the ptfe tube and check the end; maybe even turn it around. Oush it dwn and lock firmly in place.
Peter
What Peter said is exactly correct, check the PTFE tube, and if you need to you can take an exactlo knife and make sure the end is perfectly square so that way it rests against the heatbreak and there no gaps.
after that i would recommend a couple more cold pulls (atomic pulls) just like you did there (with the 90-120 range) to make sure you get everything out. Doing a cold pull like that every 10 or so prints (or as often as you like really, i do it everytime i change colors) can help keep your nozzle clean and cut down on jams.
Also as a side note, having a small roll of nylon filament around just for cold pulls is a nice thing, (i dont print with it, but i got a small sample roll specifically for cleaning as it really grabs anything in the nozzle)
Re: Extruder completely stuck, heat didn't fix it
David
My guess is that the PTFE tube is not quite square at the lower end or it is not going in all the way.
Take out the ptfe tube and check the end; maybe even turn it around. Oush it dwn and lock firmly in place.
Peter
What Peter said is exactly correct, check the PTFE tube, and if you need to you can take an exactlo knife and make sure the end is perfectly square so that way it rests against the heatbreak and there no gaps.
after that i would recommend a couple more cold pulls (atomic pulls) just like you did there (with the 90-120 range) to make sure you get everything out. Doing a cold pull like that every 10 or so prints (or as often as you like really, i do it everytime i change colors) can help keep your nozzle clean and cut down on jams.
Also as a side note, having a small roll of nylon filament around just for cold pulls is a nice thing, (i dont print with it, but i got a small sample roll specifically for cleaning as it really grabs anything in the nozzle)
I bought some nylon filament, a kind specifically reviewed for being good at cleaning printers, and some extra PTFE tubing.
I tried rotating and re-seating the existing tubing, and checked that it was square. It looks square and was in as far as I could push it, but the filament still catches a bit when I feed it in. I put in a replacement section of PTFE tube, and the filament still catches a bit.
Is this an issue or should it be OK anyway? It doesn't seem like it adds a lot of resistance once the filament is actually past the little ledge it hits.
Re: Extruder completely stuck, heat didn't fix it
David
That should be OK. Are you angling the end of the filament before inserting it?
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: Extruder completely stuck, heat didn't fix it
David
That should be OK. Are you angling the end of the filament before inserting it?
Peter
Yes, I'm cutting the end of the filament at an angle first. Thanks, I guess I'll try re-assembling the extruded assembly now and see how it goes.
Re: Extruder completely stuck, heat didn't fix it
My printer is back up and running. Everything seems to be working fine now. Hopefully the heat break won't jam again any time soon. I'm going to keep a close eye on retraction settings as that seems to be what causes this issue. Thanks to everyone who made suggestions.
Re: Extruder completely stuck, heat didn't fix it
I had the same issue with another printer and a E3DV6 full. I heated the heatbreak in a low gas flame on my cooking hob. After heating I inserted the shank of a drill bit into the heatbreak to clear the blockage. Took ages to dismantle the E3DV6 but seconds to clear the blockage in the heatbreak.
Yep retraction settings are the key, and also that the PTFE feed tube is pushed fully into the heatbreak assembly, ie it butts up cleanly on the cool side of the heatbreak.
Nigel
Life is keeping interested and excited by knowledge and new things.
Re: Extruder completely stuck, heat didn't fix it
I also had a clogged extruder. It took multiple times using the supplied "wire" to clean the nozzle and get it free flowing again. Frustrating as this is, it is easier than removing the nozzle and soaking it in a cleaner. I have had to do this a number of times with my TAZ5 printer. The nozzle on the TAZ printer is too small to use a "wire".
Another point: In order to clear the nozzle, I'm assuming that you have to command the "Load Filament" mode. That's fine for heating the extruder. But, the bed is also heated and you have to "rest" your hand/arm on the bed to get the wire into the extruder. I would like to see either the "Load Filament" mode on the MK2 modified to NOT heat the bed or add a function called "Clean Nozzle" where the bed is not heated.