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Do I have to Change Filament type on MK3S?  

Estimable Member
Do I have to Change Filament type on MK3S?

I've been using PLA exclusively on the MK3s and the Autoload feature is fantastic. Question, when I want to load PETG , how do I change the setting in the printer? when I unload it asks me what type I am unloading , but it doesn't for autoloading. Is this required? Wouldn't it clog PETG when trying to load as it defaults to PLA temperatures? 

Posted : 22/08/2022 7:11 pm
Famed Member
RE: Do I have to Change Filament type on MK3S?

You have to preheat it via the printer menu to the target temperature of the filament you're loading.

One tip: When you load from lower temperature to higher temperature filament (say PLA to PETG) you're usually okay. Just preheat to PETG and load it.

Going from higher to lower temperature filament (say PETG to PLA) carries a risk of (partial) clogging if you simply preheat to PLA and load the PLA as some of the PETG remaining in the hotend may not be cleared out completely at that temperature. So good practice is to load PLA at PETG temperatures after printing PETG and going through 3 or 4 purge cycles to get rid of any remnants of PETG. Or run a length of cleaning filament through the extruder.

Posted : 22/08/2022 7:39 pm
Reputable Member

When you unload the selected filament, the printer maintains its temperatures for a while because many people want to load the same type of filament immediately afterwards as you did until now. If you want to load a different there is the menu item preheat where you can select the material. Just wait until the hotend temp is reached, then feed the new filament, using Autoload as before. Besides: In the preheat menu you can also find cooldown even though it seems to be a little awkward to find it within the preheat menu.

Trying to feed PETG at PLA temperature might actually work, depending on set temp for PLA and type of PETG but is not recommended.

Depending on the changes, occasionally a cold-pull can remove residue that may have built up within the nozzle.

Please be aware that PETG sticks more to the bed. In case you use the smooth PEI-foiled sheet, please use e.g. some glue stick to limit adhesion. Please refer to the Prusa-manual for details.

@fuchsr was faster in answering.

Posted : 22/08/2022 7:44 pm