Troubles with extruding


I’m all out of ideas when it comes to my M300 Dual. I can’t finish any big print due to extrusion failures.

4300 hours on the clock. Material - all of them at the moment. Firmware up to date.

Small prints usually go well although I should check once more. Now I’m interested in a big print (70h). The issue is that at some point material jams somewhere and firstly starts to underextrude, hotend gathers some material on sides (sometimes) and then printer continues printing in the air with no material flowing. The extruder stutters as the pinion can’t rotate and grinds the filament.
Happened twice at something like 10-15 hours into the print.

The stuttering sometimes happens soon after a print starts, sometimes just after loading material.

I’ve done the extruder maintenance, cleaned everything. I’ve switched the pinion. I’ve replaced nozzles and hotend to new ones. Happens with both 0.4 and 0.6mm diameter. I’m conducting test on PLA. I’ve fooled around with different extrusion temperatures. I’ve tried different speeds and material flow (let us finally see and change absolute print speeds damn it!)

What unclogs it? Pushing a thin metal cord through the nozzle while the material is loading helped twice (not far into the nozzle, couple of cm). Unloading and loading material helps sometimes. Once in a while just pushing the filament with bare hands while it works solves the issue. Sometimes I need to disassemble the extruder, this always works. But soon after any of that the issue comes back. And I mean few minutes…

It’s really hard to pin down where and why it clogs. When I push the filament through the system everything seems to work well.

Well now something different came up. While loading the filament comes out at an angle, I observed it for a long time but it used to work fine. Today it also immidiately curles around the nozzle and that’s why it fails to print fine layers at the moment. Again…new hotend with new nozzle, only 1 material being printed - PLA.

Here’s how the filament looks like after unloading. Seems different to what it used to look like.

Hello @Tommar,

are you printing with Zortrax PLA, or some external filament? Have you also experienced the problem with different materials?

Since you already replaced the hotend module, but the issue persists - I am wondering if some part of the whole extruder (for example the motor) could be affected. Would it be possible to record how the printer behaves as soon as the problem starts? If you could provide some files - please, send them via support form, so we can pass the case to the technical department.

Best regards,

Thanks for taking interest.

So I’ve taken the whole thing apart. Cleaned thoroughly, adjusted all the axes really carefully, placed all the nozzles in acetone for a few days, cleaned them mechanically and now I’ve been printing for a few days without such issues.

I believe the problem arises from using TPU (flex) filaments. They must be clogging nozzles, however idk why even nylon won’t clean the nozzles off of it ;/