Elevated hotend printing temperatures  

RE: Elevated hotend printing temperatures

Posted by: @nurse-farva

Hi all. I have printed with the Prusa Mini for two years now. It started running into clogging issues, so I replaced the nozzle. That worked for a short period of time, but I started running into the same clogging issue. I found out that if I increase the print temp for PLA up to 230-240 C it runs great. I didn’t feel super comfortable with those temps as I always printed this same PLA at 200 C. I replaced the hotend and it still clogs when trying to print at 200, but runs well at 240. I have run PETG through and same thing. Have to add about 20-30 degrees to the usual print temp for it to print well. Any thoughts on why that could be or how to fix?

Exactly what parts did you replace? Did it include the hot end PTFE tube? Those wear out. You have to follow Prusa's instructions to the letter when working on the hot end.

Regards,

Mark

RE: Elevated hotend printing temperatures

The mini is susceptible to heat creep which causes the PTFE tube to shrink.  When this problem bit me I replaced my heat break with one from Bondtech that mates the PTFE tube higher up in the break to reduce the temperatures that cause the PTFE tube to shrink.

Cheers

-Bob

RE: Elevated hotend printing temperatures

I replaced the entire hotend assembly with the exception of the fans. That includes the heatbreak, the PTFE tube within, the heater block, and the nozzle. It was performing the same prior to the change as it was after the change. Still needs to be at 240 to print PLA. It’s annoying because any changing of filament and first layer calibration auto sets the nozzle temp at 215 which isn’t hot enough and the extruder with just grind the filament trying to shove it into a “cold” nozzle. 

RE: Elevated hotend printing temperatures

I have replaced the PTFE tube within the heat break. That did not have an effect on the situation. 

RE: Elevated hotend printing temperatures

Maybe your temperature sensor started to degrade and thus reports higher temperature than it actually is. This way PID controller thinks the hot end temperature is okay but is not because it is too low, thus you would have to bump the temperature.

There are some multimeters with thermocouple sensors - maybe some of your neighbours has it and you could check the temperature of the printer when it's hot, to check the actual reading.

RE: Elevated hotend printing temperatures

That’s an idea. I do have a temp reader. I could try that. I didn’t replace the heater cartridge or the thermistor. I guess I felt like if those were bad the temp would read correctly. I will try that and maybe order new wires. Thanks