Hi everyone, I'm having constant clogging issues with my printer that sprung up out of nowhere. I'm running out of things to test.
The printer had been running several prints a day for several days when I decided to change nozzles for one print. Ever since then (~2 weeks ago) i have not completed a single print, due to clogging. I have tried:
Replacing the PTFE tubing in my hotend.
Replacing the nozzle. (I've used a handful of nozzles, all with the same results)
Trying different filament.
Replacing the hot end with an all metal hot end, trying three different heat breaks from two manufacturers.
Removing the printer from its enclosure to ensure proper cooling.
Adjusting extrusion tensioner.
All the other basic obvious stuff like making sure there's no blockages anywhere (whole hot end and nozzles have been soaked in acetone, torched, brushed etc).
The printer will seem to work fine for a little while before either slowly failing to extrude until it completely jams, or it completely jams all at once. I don't think it's heat creep, because I tried setting the nozzle to printing temp, letting it sit for half an hour or so and running filament through it and it had no issue, whereas prints usually start to fail within the first 10 minutes. It also doesn't have anything to do with my print settings because I'm able to get it to clog sometimes by just running the extrude command.
I'm completely at a loss here. I don't know what else to try. Does anyone have anywhere else for me to look?
Update: I tried detaching the heat block from the rest of the printer and running filament through the (cold) heat break, and it got clogged. There was a small bit of filament adhered to the inside of the heat break. So it's apparent that's where the clog is forming, it's just a matter of finding out why it's happening. Everything seems to point towards heat creep, but even when I intentionally try to heighten the conditions that to cause heat creep I can't intentionally replicate the clog. I'll keep experimenting down that route, though.
Update 2: After clearing that clog, I noticed the short piece of Bowden tube between the top of the heat break and the top of the heat sink was slightly too short. I modified the heat sink to bypass this short piece altogether; the Bowden tube now goes directly from the extruder into the heat sink to the top of the heat break. I also applied a thin layer of thermal paste to the outside of the heat break to ensure good contact/ heat transfer with the heat sink.
After doing all of this, I ran a PID tune and, with my AC set to lower than average, started extruding filament. After extruding ~300mm of filament, I tried a few nozzle and filament swaps using very careful techniques to avoid leaving any residue. I'm able to pull the filament out in a solid piece to where I can see light through the nozzle afterwards. Then, finally, out of the blue, the clicking returns. Another clog. I wasn't able to remove the filament as cleanly this time to inspect the clog, but I'm strongly suspecting heat creep at this point, despite going above and beyond to mitigate it. It's quite late though and I've got work tomorrow so it'll have to wait until then.
It is either in between the nozzle and heat break, or in the heat break. I'll have to experiment a few more times when I get home, but one time removing the nozzle did not fix the clog, while another time removing the nozzle did fix it.
Cold pulls, warm pulls, and shoving filament in until the clog clears. All clear it for a while until it eventually clogs again.
Gradual increase in frequency of ticking noise coming from extruder motor (Bowden setup) and decrease of filament extruded until eventual complete clog.
See above, either pulling it out or pushing it through.
I will have to check temps when I get home. There is no cooler on the extruder. I have not adjusted the Vref (had to look that up), but I originally tried tuning the stepper rotation distance before I knew there was a clogging problem.
At this point the hot end has been disassembled, cleaned and reassembled probably close to 50 times in the last 2 weeks. It's been done cold while disassembled, hot on the printer, after the nozzle has been torched from cleaning, you name it. Both nozzle and heat break are as tight as they can be.
Yup
The printer clogs even outside of prints, so retraction is not an issue.
Nope
I had not heard of PID tuning until reading comments today. I might look into it when I get home, but as I've said other places I don't think heat is an issue as reported idle temps are same as the build plate and clogs are able to be fixed by pushing filament through the heated nozzle. Also, filament still oozes from the hot end while clogged. I've tried printing at recommended temp, as well as far below and far above recommended, doesn't change anything.
Yes, but not enough to "test" it - what I'll try is disconnecting the heat block, leaving the heat break attached to the printer, heat the nozzle, then try running ~1m of filament through the (cold) heat break. I'll have to report back in a few hours when I get home.
Its important to tighten nozzle properly. Tighten it, heat it up, tighten more, done. Both heat break and a nozzle must be clean. It's the only way to achieve a good seal.
I've read your update in OP, how did it clog in the heat break? Do you have a picture? Can you run the same test without heat break, just extrude cold filament in the air (no bowden tube). That test would show if your extruder is working properly. I still think you might have stepper driver or motor overheating. If the test doesn't fail it would mean you should look into bowden tube/heat break
I repeated the test I attempted after clearing the clog (heat block detached, heat break and Bowden tube still attached) with 1000mm of filament through the cold heat break and it went fine. I've updated the post again; strongly suspecting heat creep. I have no idea what else I can do to try to fix it, though. I'll try again tomorrow.