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.
I’ve tested and verified that there isn’t a gap between the two by following this process:
Tighten the heat break all the way.
Tighten the nozzle all the way.
Loosen the heat break partially.
Verify that the nozzle is now able to be tightened further.
If the nozzle goes in further after loosening the heat break, this confirms there is no gap; however, if either nozzle or heat break isn’t perfectly flat, it could theoretically leave a tiny space. I don’t know if this is a common issue, but I’ve tried with multiple heat breaks and nozzles, so I don’t think this is it.
Stupid question, but there isn’t any kind of “gasket” that is meant to go between the nozzle and heat break is there? I can’t shake the feeling this spot is the cause of my concerns.
It sounds like you’ve done it perfectly. I’d suggest trying a different heatblock, but I doubt that would make a difference. Make sure they are all aligned in your extruder with no obstruction when you look through end to end.
I’ve had to do some heating and cleaning of my heatblock and heatbreak when replacing parts to remove bits of plastic. (Gentle wire brush and a burner lighter).
The only other thing that comes to mind is your thermistor or heatblock cartridge being damaged and reporting the wrong temperature. Temps too high or too low can lead to clogging.
If I were you and I had tried all these things, I would get a new extruder and see if that fixes the issue.
Maybe recut the Bowden tube to make sure it’s not at an angle?
And then loosen the nozzle, push the tube all the way in and use the retaining clip, then tighten the nozzle into the heartbreak while it’s hot.
Use an x-acto knife or a $5 PTFE cutter for best results.
And cut it with filament inside to keep it from deforming the cut too.
It’s an all metal hot end, so the Bowden tube does not run down to the nozzle.