Thermal Run-away Issue (All of a sudden)
So I have a Prusa i3 clone (made by FLSun) and today out of the blue I'm getting thermal runaway when trying to print. (Slicing using Slic3r Prusa Edition).
I have my first layer set to 205 then drops down to 195 for subsequent layers. When the second layer starts, the heater starts to cool down, but goes beyond 195 (drops to about 190) then starts heating back up. Except it seems to have trouble actually getting back up to 195. This must trip the thermal runaway protection in the firmware as it's not getting back to the target temperature in the given time (that's my understanding of the Marlin firmware's protection).
If I print at 195 for all layers, I don't have this issue at all. I've just found that printing at 205 for the first layer improves adhesion, but it's too high for the rest of the print (I get a lot of stringyness printing this particular filament at 205).
Any suggestions on where to start to fix the problem? I finished a four hour print last night that turned out perfectly fine, and went to re-print the same thing this morning and the issue occurred. What are the most likely suspects?
Posted Feb 15, 2018, 8:35 PM UTC
I had a similar issue, when the temperature would drop to the lower temp & simultaneously the cooling fan would kick in.
Performing a Pid autotune at the lower temperature with the cooling fan fully on fixed it for me
I'll read up on that, thanks for the hint. For now I'm just printing at 195 for all layers and it's working ok. Using masking tape and a glue stick and getting decent bed adhesion that way.
I use to do this via G-codes but I guess on your printer there is even an option to do it directly in the menu.
I ditched the masking tape as well as heated bed completely. I am now printing directly on a glass bed with 210, after the first layer I switch to 190. As adhesive I use Uhu magic stick (the blue stuff) and since that I have not had any warping or other adhesion issues.