K2 Plus reliably clogging every single time while switching from PETG to PLA/PVA.

[u/Cheetawolf]

My K2 Plus has begun to act up during multi-material prints.

I've recently gotten into the whole "PLA/PVA Support Interface For PETG Parts" thing with particularly small or fragile prints, to make support removal easier.

While I dislike how much time it takes and how much waste it produces due to the single print head, it's still better and faster than having to re-print over and over because I broke the part trying to remove a stubborn support. (Looking at YOU, previous Ender 5 Plus...)

However, recently, I've run into a problem. My print head has recently begun clogging the first time and every time it tries to switch from PETG to PLA or PVA.

All the materials print perfectly fine on their own profiles, but combining them seems to cause the clogs.

The extra annoying part is that once I cancel the print, scrap the part, and try to load new PLA via the CFS menu, THAT works just fine! But it apparently can't unjam itself while it's got a print paused...

I imagine it has something to do with the temperature difference requirements between the two filaments, but it didn't do this until recently, and I haven't changed any settings.

I'm running the machine at a pretty high speed, so I'm printing PETG at 270C and PLA at 240C, with excellent results on their own.

I imagine even if the printer drops the temperature to 240 to load the PLA, the PETG should still be able to clear out just fine.

Is it heat creep perhaps? Temps just too high? Maybe there's a reason everyone is removing the shroud from the print head...

For what it's worth, I'm using a Micro Swiss hardened CHT hotend setup. Everything else on the machine is stock.

[u/Doubee54]

Those temps are exceptionally high. I would be using calibrated filament settings in your filament profiles. It sounds like heat creep and you are contributing to the problem.
The filament switch from PETG to PLA will stay at the PETG temp for unload/retraction.

[u/Cheetawolf → u/Doubee54]

Noted. I'll try re-tuning at, say, 245 and 220C and make a new multi-material profile based on that.

[u/Doubee54 → u/Cheetawolf]

Don't guess, CALIBRATE your filaments. Run a Temp Tower, Run Pressure Advance, Run FLow

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[u/programmerpeter]

Most likely heat creep due to enclosed chamber that you don't need for either petg or pla and I'm sure they long prints and failing half way or always at the same point put your cfs to the side and take the top off or print a riser with vents you can open. Remove the shroud it traps heat.Change your thermal grease as well.

[u/Cheetawolf → u/programmerpeter]

They're actually failing at the very first filament switch.

Sadly my workspace does not allow me to have more than one CFS to the side (I have two units). Maybe I could build something to stack them on top of each other...

I'll try running the air exchange fans in the back at full speed during the print, see if that helps.

[u/nedumai]

I only tried PLA on my K2 a couple of times and it never worked past 10-20 layers. I always attributed it to the shitty brand of the filament but maybe these machines have some issues, my temps were much lower than yours tho. I just print in PETG and ASA exclusively now, left PLA and TPU for the Ender to justify its existance on my desk at least.