Scary amount of smoke and molten plastic spitting from nozzle of 18 month old Prusa i3 Mk3s
As the dramatic title suggests, I've just had a fairly worrying amount of smoke and beyond motion plastic firing out of the nozzle of an 18 month old Prusa i3 Mk3s.
This particular machine has been used for hundreds of prints but not turned on for about 6 weeks.
I turned on both of my Prusas this evening, settings to heat for PLA and unloaded a few inches of filament that had been left from the last prints. I loaded 2 brand new reels of Fillamentum Iron Grey fresh from the packs and set both machines printing. Everything looked normal. I always sit and make sure the first layer looks like everything is fine and I'm glad I did. The nozzle of one Prusa was smoking a little and making a spitting noise, the extruded plastic was beyond molten and it's now sticky as though it's been heated beyond its highest viable temperature. I turned the Mk3s back on and unloaded the filament and reloaded it again. Crazy amounts of acrid smoke filled my office like a smoke machine and molten spitting plastic also erratically fired out of the nozzle. Temps read normal. This machine has had a new thermistor since June. I haven't tried a different filament yet. The problematic Prusa is unplugged, its slightly older and far more used sibling is happily printing away. The nozzles were last changed a week or so before the printers were last used so not much mileage on them. Everything appears to be fine but that was slightly alarming.
Any advice or tips as to what diagnostics to run or what and where to check please?
Thank you
RE: Scary amount of smoke and molten plastic spitting from nozzle of 18 month old Prusa i3 Mk3s
What was the previous filament that was left in it? Any chance it was steam you were observing from the water it had absorbed cooking out? Some filaments can absorb crazy amounts of water over time and will spit and steam quite a bit as you describe if you try to print without drying it. PLA can also get very brittle and so when you unloaded it it may have broken off and not removed all of the old stuff.
If the smoke was coming out of the nozzle I'd probably be a little less concerned than if it was coming from elsewhere. But in the interest of safety it might be good to do a teardown of the extruder, both to inspect all the parts for the source of the problem, and confirm everything is indeed fine before trying again.
RE: Scary amount of smoke and molten plastic spitting from nozzle of 18 month old Prusa i3 Mk3s
Start by unloading the filament.
I would acquire a remote reading temperature probe and check the external nozzle temperature.
If it is anywhere close to the thermocouple reading, you are OK.
If it is wildly higher - check why. Thermocouple not seated correctly, defective, etc.
Run cleaning filament through and then try a different role. My guess is for moisture in the filament.
RE: Scary amount of smoke and molten plastic spitting from nozzle of 18 month old Prusa i3 Mk3s
@vintagepc
The filament I unloaded was an orange Fillamentum filament, I unloaded it, loaded a brand new Iron Grey fillamentum filament from the vacuum packaging and when prompted if the colour was correct I pressed 'no' to clear the orange and when prompted again, pressed 'no' so the orange was as cleared as possible and the grey looked like it was running without any previous colour tainting it.
When it first started smoking and squirting out plastic I stopped the print and unloaded the grey filament, reloaded it and it was worse than before, at first I thought it was an electrical fire then saw the smoke really blasting out of the nozzle so definitely contained in there, if it was moisture, I've seen a GIF of someone's nozzle smoking mine was considerably smokier. (I wish I'd filmed it)
I'll strip things down after some temperature checks and thoroughly check and clean everything.
Thank you
RE: Scary amount of smoke and molten plastic spitting from nozzle of 18 month old Prusa i3 Mk3s
@robert-rmm200
Thank you, I've ordered a remote temp. probe and some cleaning filament to run checks as you suggested.
From the comments and a bit of research, moisture might be the problem but I'll check thoroughly as it was fairly dense acrid fumes it was kicking out which worried me after hundreds of nights letting the Prusas run through the night.
RE: Scary amount of smoke and molten plastic spitting from nozzle of 18 month old Prusa i3 Mk3s
Did you ever find a solution? I'm having the same issues with my first prints ever. I've tried cleaning filament and cold pulls with the cleaning filament. I did get the cleaning filament to come out nicely eventually but there was still smoke. I tried burning it off for a while but it won't stop. I guess I need to tear down the extruder and inspect everything is a-ok.