I just Cleared an Awful Extruder Clog
I love my MK3. I've always been fascinated by sculpture but have lacked the manual dexterity to realize my ideas, so this printer has unlocked my creativity in ways I couldn't have imagined! It's almost always running, and just like every other 3D printer owner, I've run into my share of clogs and other issues. That said, I just took care of a doozy.
I've been experiencing intermittent nozzle clogs during my prints, which have been annoying but not that big of a deal. It ruins the print obviously (unless I catch it early by hearing the extruder clicking), but resolving the clogs has generally been as simple as unloading the filament, snipping the end, and then reloading it. Then, today happened.
I queued up a couple of Gloomhaven Oozes, then went to work. When I got home, I found that I'd run into another clog, about 1 cm into the print. This was the 3rd failed print, due to clogging, of these two oozes. I went to do the usual unload thing and it didn't quite feel right. So, I took a look at my bowden extruder and found that the gear had slid all the way to the far end of the shaft and was no longer in line with my filament! Besides that, there was all sorts of ground filament around the gears, where they had worn it down before everything slipped out of alignment.
Well, that's annoying, but easily resolved. I removed up the screws for the idler and opened it up, then re-oriented the gear on the extruder motor and pulled out my 1.5 mm hex key to tighten it back in place. With the gear back in place (and the dust cleaned up), I tried to feed back in my filament and, after several centimeters, there was that awful extruder motor clicking once more. I quickly released the tension on the idlers and thought about what to do.
I decided to mark the top of the filament, then unload it and try to figure out exactly where it was jammed. So, I did that and found that the new filament had gotten almost all the way down the hot end before jamming - it was about 2 cm short of the nozzle. Not sure what to do, I did some quick searching and found a Prusa article on Nozzle Clogs.
I followed their steps with turning the temperature up to 250 and trying again, but to no avail. I had some wire in the garage, but it measured at 1.8 mm, so I didn't feel entirely safe shoving it down a channel that's designed for 1.75 mm filament (and the instructions say to use a 1.5 mm wire). I found some thinner wire, but it was much thinner: 0.9 mm. Still, I figured that I'd give it a go with the thinner wire.
Just like with the filament, I found that I had a clog a couple centimeters above the nozzle. I was nervous about shoving this wire down into my nice new .25 mm nozzle, so I decided at this point that I'd just take it off. After removing it, I pushed the wire more vigorously and got through the blockage... but nothing was coming out of the hot end except for the wire. I tried various poking, twisting, and thrashing techniques, all to no avail.
So, I did the next thing that any nerd will do: I went to reddit. On reddit, someone had mentioned using a hex key to clear a nozzle jam and I just about face-palmed. Literally sitting on the table next to my printer, sat the 1.5 mm hex key that I had used on the bowden gears earlier. It wasn't long enough to make it down from the top at the filament entrance, but it was exactly long enough to go up from the bottom and get to the bowden gear chamber.
So, I shoved the long end up the hot end. Wow, phrasing. Seriously. Anyway, I immediately got some resistance when I pressed against the clog, but I worked at it with slow, constant pressure, until I could insert it deeper and deeper.
Eventually, the hex key got pretty hot - the hot end was at 250 degrees this entire time, after all, and I was getting a little worried about my fingers slipping or the tension suddenly releasing and then slamming my fingers directly into the hot end. So, I grabbed my pliers and used them to push in the hex key the rest of the way.
Just as the key was about to get to its bend (aka, it wasn't going any further than that), the tension suddenly released and a hideous glob of silver PLA rocketed out of the open extruder door. I had done it. Confident in my clog cleaning abilities, I withdrew the hex key (now quite hot) with the pliers and reinstalled my nozzle. Then, I loaded up the filament and was happy to see that magical thin line of molten plastic flowing freely once more!
Now though, I'm left with a question about cause and effect. Were all of those mini clogs that I experienced part of a decaying system that eventually had enough problems to fail catastrophically, or was this just a particularly bad instance of the recurring clogs that I've been seeing? I certainly hope that my "solution" of unloading and reloading filament was the problem - perhaps it had been leaving little strings and bits of newly-hardened PLA stuck on the sides of the PTFE tube, which eventually built up into the monster clog. I sure hope that's what happened, because I think that's pretty well resolved at this point. I suppose time will tell, so I'd better print a whole bunch more things to see what happens! You know, for science.
I've been experiencing intermittent nozzle clogs during my prints, which have been annoying but not that big of a deal. It ruins the print obviously (unless I catch it early by hearing the extruder clicking), but resolving the clogs has generally been as simple as unloading the filament, snipping the end, and then reloading it. Then, today happened.
I queued up a couple of Gloomhaven Oozes, then went to work. When I got home, I found that I'd run into another clog, about 1 cm into the print. This was the 3rd failed print, due to clogging, of these two oozes. I went to do the usual unload thing and it didn't quite feel right. So, I took a look at my bowden extruder and found that the gear had slid all the way to the far end of the shaft and was no longer in line with my filament! Besides that, there was all sorts of ground filament around the gears, where they had worn it down before everything slipped out of alignment.
Well, that's annoying, but easily resolved. I removed up the screws for the idler and opened it up, then re-oriented the gear on the extruder motor and pulled out my 1.5 mm hex key to tighten it back in place. With the gear back in place (and the dust cleaned up), I tried to feed back in my filament and, after several centimeters, there was that awful extruder motor clicking once more. I quickly released the tension on the idlers and thought about what to do.
I decided to mark the top of the filament, then unload it and try to figure out exactly where it was jammed. So, I did that and found that the new filament had gotten almost all the way down the hot end before jamming - it was about 2 cm short of the nozzle. Not sure what to do, I did some quick searching and found a Prusa article on Nozzle Clogs.
I followed their steps with turning the temperature up to 250 and trying again, but to no avail. I had some wire in the garage, but it measured at 1.8 mm, so I didn't feel entirely safe shoving it down a channel that's designed for 1.75 mm filament (and the instructions say to use a 1.5 mm wire). I found some thinner wire, but it was much thinner: 0.9 mm. Still, I figured that I'd give it a go with the thinner wire.
Just like with the filament, I found that I had a clog a couple centimeters above the nozzle. I was nervous about shoving this wire down into my nice new .25 mm nozzle, so I decided at this point that I'd just take it off. After removing it, I pushed the wire more vigorously and got through the blockage... but nothing was coming out of the hot end except for the wire. I tried various poking, twisting, and thrashing techniques, all to no avail.
So, I did the next thing that any nerd will do: I went to reddit. On reddit, someone had mentioned using a hex key to clear a nozzle jam and I just about face-palmed. Literally sitting on the table next to my printer, sat the 1.5 mm hex key that I had used on the bowden gears earlier. It wasn't long enough to make it down from the top at the filament entrance, but it was exactly long enough to go up from the bottom and get to the bowden gear chamber.
So, I shoved the long end up the hot end. Wow, phrasing. Seriously. Anyway, I immediately got some resistance when I pressed against the clog, but I worked at it with slow, constant pressure, until I could insert it deeper and deeper.
Eventually, the hex key got pretty hot - the hot end was at 250 degrees this entire time, after all, and I was getting a little worried about my fingers slipping or the tension suddenly releasing and then slamming my fingers directly into the hot end. So, I grabbed my pliers and used them to push in the hex key the rest of the way.
Just as the key was about to get to its bend (aka, it wasn't going any further than that), the tension suddenly released and a hideous glob of silver PLA rocketed out of the open extruder door. I had done it. Confident in my clog cleaning abilities, I withdrew the hex key (now quite hot) with the pliers and reinstalled my nozzle. Then, I loaded up the filament and was happy to see that magical thin line of molten plastic flowing freely once more!
Now though, I'm left with a question about cause and effect. Were all of those mini clogs that I experienced part of a decaying system that eventually had enough problems to fail catastrophically, or was this just a particularly bad instance of the recurring clogs that I've been seeing? I certainly hope that my "solution" of unloading and reloading filament was the problem - perhaps it had been leaving little strings and bits of newly-hardened PLA stuck on the sides of the PTFE tube, which eventually built up into the monster clog. I sure hope that's what happened, because I think that's pretty well resolved at this point. I suppose time will tell, so I'd better print a whole bunch more things to see what happens! You know, for science.
I know that for me anytime that I have had a clog it has usually been due to one of two things; filament quality or dust.
ReplyDeleteAs far as filament quality the first jam that I had was actually due to what looked like a piece of paint flakes that were in the defilement. Getting that jam out was a bit tricky and was the first time that I used the method of "cold pulling". I will link a video for you on this topic but so far this has solved any problems with jammed nozzles that I have had. Was this clog from the stock Prusa filament? Also I will make sure to bring you some of the filament that I have for doing "cold pulls", as I have a good amount of it and don't need to use that much when there is a clog.
The other issue being dust which unless you are willing to build an enclosure to keep the surrounding air mostly isolated it something that will be around no matter what. For me my house is always pretty dusty and so (fingers crossed) I have not really had any issues with it so far. I have toyed with the idea of printing up some filament cleaners that would be put on the frame of the printer to clean the filament as it goes into the extruder, but so far I have not needed it.
Tom's video on clogged nozzles:
https://www.youtube.com/watch?v=g8uvh6kvr54&t=246s
Thanks for the info! Yes, this was with Prusa filament. I've seen some forum posts that question the quality of that filament, however I suspect that's mostly just an example of the internet amplifying an outlier experience. I installed a filament cleaner (just the kind that clamps onto the filament and wipes it as it gets pulled into the extruder), but either it's not doing much to help or my house is excessively dusty!
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