Air-printing cooking the filament?

Hi All,

So I’m going through a roll of filament each week now, and I’ve noticed a lot more failures than usual. Specifically, I’m getting a MTTF of around 30 hours, so I’m limited in the complexity of models I can print, as if I print multiples for around 14 hours, I’m running a high risk of failure and I lose about 30% of what I print. Which is pretty poor compared to my old Up Mini, which had a MTTF of around 500 hours and was rock solid, despite the lower quality print…

Anyway, today’s failure - Had an early air-print and printed to air for around 6 hours. After that, I couldn’t clear the nozzle. So I disassembled it and I’ve noticed that when I air-print for too long, it cooks the plastic in the heater.

Previously, the filament was inside the nozzle, but the latest printers use a wide thead nozzle and the plastic is inside the heater - And cleaning/changing the nozzle didn’t work - it jammed almost immediately, so I removed the nozzle and ran an extrude operation, and what came out looked pretty bad. It was crispy, sticky and twisted around a lot before clear plastic came through once again.

Then I cut the plastic off at the heater, refitted the nozzle and ran again. It’s printing once more.

Anyway, this was a particularly bad jam and I’m thinking that the lack of a filament movement detector is causing major problems with air printing - to the point that once it air prints for a few hours, it cooks the filament inside the heater, and will cause problems unless the heater itself is flushed with clean plastic prior to re-installing the nozzle.

Has anyone else had similar observations and/or problems just after hours of air-printing?


Maybe its the filament, i have the same problem with a up mini 2 and tiertime filament, no matter if it is pla or abs.