Hotend doesn't heat beyond 170° anymore
As the title says: when preheating for PETG (230/85), the hotend stops heating at 170° and the temperature indicated on the screen starts flashing green (indicating it reached it's temperature I guess?). When I do the selftest, it fails at the same point...
What I did before this issue happened was the following:
- Took out the nozzle for a thorough cleaning
- Re-inserted the nozzle
- 1-2 (semi-) successful prints and then it wouldn't heat anymore
Did I touch something I shouldn't?
There is a bug in 4.2.0 firmware that it only preheats to PLA temperatures during the first layer calibration https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/826 were you trying to calibrate the first layer or just print?
It's realy when I'm trying to print...
It's a feature, not a bug.
Preheat function improved
Several optimizations were made to the preheat function in order to shorten the overall time before the actual print is started. Now, regardless of the target print temperature as soon as the temperature of 170 °C is reached, the printer will allow for:
- the filament to be loaded to the print head
- the mesh bed leveling (MBL) to be performed
Also, the lower temperature in the print head prevents the filament from dripping down onto the heatbed. Once the MBL procedure finishes successfully, the printer proceeds to heat up the hotend to reach the target temperature and starts the print.
Preheat scenario (PLA used as an example):
- The user selects “Preheat” from the menu and then the material (PLA) they intend to load. The print head starts to preheat to target temperature (215 °C), but stops at 170 °C.
- As soon as the temperature of 170 °C is reached, the number on the screen starts to flash green, informing the user that the printer is ready to load the filament.
- For advanced users - the printer is also ready to perform the Mesh Bed Levelling, if this is specifically set in the G-code
Print scenario (PLA used as an example):
- The user selects “Print” from the menu, the material (PLA) is already loaded. The print head starts to heat up or cool down to reach the temperature of 170 °C. However, the printer knows (and displays) that the target temperature is 215 °C.
- The heatbed is heated up to the final temperature, in our case 60 °C
- As soon as the temperature of 170 °C in the print head is reached, the printer performs the MBL procedure.
- Once MBL is successfully finished, the printer continues to heat up the print head to the target temperature and starts the print.
This may sound silly, but exactly this scenario plays out when your G-code file is damaged. I forgot to eject, so the USB stick had an empty file with the correct name. The printer stopped with 170/210 blinking white/green and just stood there. The condition can be recognized as when you select print there is no preview, just the file name is shown. I think there should be a warning message.