Thermal Runaway on higher temp prints, Original I3 MK2
I built the Original I3 MK2 last part of Sept 2016 and it's printed perfectly since then, an amazing machine. I recently started doing some higher temp prints (thanks to 3DLabPrint and their great designs) and started getting thermal runaways if the print fan is running. Anything above 155 on the print fan will cause the hotend temp to slowly drop until it triggers a thermal runaway. With no print fan on there is still a 5 deg temp swing around the target temp, something I never saw at lower temps.
I've noticed that others in the forums have reported similar problems on machines from the same time period, so I'm wondering if possibly Prusa had a batch batch of heater modules from E3D. I realize that the heater is an expendable item that degrades with use, but I bet I haven't put even 5 rolls of filament total through it yet. I'm still running on the same E3D heater cartridge my other printers came with 2 years ago, so I do expect more out of this one.
Chief
Re: Thermal Runaway on higher temp prints, Original I3 MK2
A potential fire hazard was discovered so lower wattage heaters were used until issue was fixed. Contact PRUSA to find out what wattage you have and then see what they can do for you if not 40 Watt.
Re: Thermal Runaway on higher temp prints, Original I3 MK2
HI,
I've had this problem since my Mk2 upgrade.
I just kept the part fan quite low (40% and 60% when bridging) when printing higher temp filaments and all worked well.
Then I found this and swapped out the part fan nozzle for this. http://www.thingiverse.com/thing:1947953
Makes a big difference. Allows me to up the part fan speed somewhat.
I did have to tweak the design a little to fit snuggly on my machine.