3DPrinting
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I was pulling my hair out over poor bed adhesion with PETG while I was having no issues with PLA. As in, completely failing a first layer test with PETG turning into spaghetti while PLA printed perfectly.
Turns out that PETG seems to be more sensitive when it comes to how clean the bed is. Scrubbed the bed with water and dish soap and the same gcode that was producing spaghetti was now printing without any issues.
On my Prusa printers - different surfaces work better for different materials. For example PLA works great on smooth PEI surfaces. But PETG has trouble sticking - PETG works better on the textured or satin PEI sheets which have a more "grippy" surface for PETG (and TPU).
Pro tip from experience - when using textured build surfaces, be sure to increase first-layer nozzle temp an extra 5c to 10c - this helps the plastic really ooze into the crevices of the textured surface.
With my Satin PEI sheets on my Prusa printers, I just printed 4000 items for a wholesale partner on three different MK3s printers (all dialed in and running as intended) - roughly 3000 hours of print time. Not a single time did I have a part pop loose mid-print, and I still haven't cleaned the surfaces in over a year. But I also don't use any extra "adhesives" like hair-spray or glue-stick to increase adhesion. All I need to do is pop off the pieces of scrap plastic (like the 1-layer skirt and bleed line at the front of the build surface and print the next copy of the parts.
If you aren't using a PEI build surface, you don't know what you're missing lol
I'm exclusively using textured PEI surfaces on my printers, and I can strongly recommend them as well. That's why it was so surprising to see PETG refusing to stick, even though my first layer with PLA was having no issues at all.
I mostly print PLA, and I was just done doing maintenance on the frame and doing some calibration, etc. Everything was dialed in - the only thing I didn't bother with was the bed because I had no issues with PLA.
Literally, the only change between PETG spaghetti and a great first layer was cleaning the bed.
That's so strange, I have no problems printing PETG all the time. Like I said, I have different PEI sheets for my Prusa printers - smooth for PLA, textured and satin sheets for basically everything else. Honestly though I probably print PETG 95% of the time, I only use PLA plastic for prototyping because I have a lot of rolls just sitting around.
What are you cleaning the bed with? What kinda printer?
Yeah, I don't know - I've never had any big issues in the past with it either (I mostly print PLA+ though, unless I need something more heat-resistant for my car or outdoor use).
This particular issue was with an Ender 3 V2 running a BLTouch and an aftermarket textured PEI sheet in an enclosure - so there were no drafts or anything that would explain the bad adhesion either. Just scrubbed it with some water and dish soap. That was literally the only thing I messed with between the spaghetti result run and a great first layer run, so I figured I'd mention it in case it might help OP.
Ahhh, see from my Zortrax printer I learned that PETG benefits from no enclosure - drafts are fine. It actually helps increase print quality. I run my Prusa Mk3s printers with no enclosure (since I only use them for mainly PETG and TPU, and occasionally PLA). I have Zortrax printers for my ABS, ABS/PolyCarbonate Blends, and HIPS plastics (but holy hell I hate the closed software on the Zortrax printers and their Zsuite slicing software - absolute garbage which cripples printers that cost thousands of dollars - I can't even tweak temperature, fan speeds, flow rates, etc mid-print like literally every other printer I've handled over the past decade!).