I’m currently having a bit of difficulty printing on my P1S machines with PETG. Specifically, I’m having a LOT of instances where the print loses bed adhesion and I end up with unappetizing spaghetti. My typical setup is that I have the Bambu liquid glue on the plate (the textured PEI that came with the printer), the door closed, and the top glass slightly vented (I do a lot of overnight printing, so my house gets down to about 62 degrees in the winter). I also have, in the filament start g-code, a Z-Offset of +0.03, which I take to mean that the nozzle is moved slightly FURTHER from the build plate - please correct me if I am wrong on this. With all that in mind, here are my questions:
Should PETG be printed with the chamber closed, partially open, or fully open (top off)?
Should PETG be printed with glue on the build plate or without?
Clarification on whether a Z-Offset of +0.03 means closer to the plate or further from the plate.
I print PETG on a regular basis with my fully enclosed P1P (after market P1S) and I don’t use glue. Each time you remove a print from the bed spray the PEI bed with IPA and wipe the IPA off with a micro-fiber towel and you will have much more success.
In your case, I would thoroughly clean the bed with soap and water to get the glue off and then dry. Once it’s dry spray with IPA and wipe with a dry micro-fiber cloth.
If you are printing models with very little surface area touching the bed or very narrow tall models you’ll want to enable the “brim”. I usually use a 10mm brim in those cases.
Hotter bed temperatures can help with some PETG filaments too.
I apologize, I didn’t really answer all of your questions…
Should PETG be printed with the chamber closed, partially open, or fully open (top off)? Closed is fine (unless the room gets unbearably hot)
Should PETG be printed with glue on the build plate or without? See my previous reply
Clarification on whether a Z-Offset of +0.03 means closer to the plate or further from the plate. “+” means the offset is away from the plate or higher up the Z axis. I would use Elephant Foot Compensation before messing with a Z offset. It only affects the first layer, where the offset is going to affect all of your layers.
PETG is a challenging filament to print. It likes to be stringy. And the strings tend to collect on the nozzle until they’ve built up enough to snag on the print, leaving a blob behind, which cools quickly and becomes very hard. When the nozzle comes around to that spot again, it hits the solid blob and that knocks the print loose.
These 4 things were printed on the same run. The short one got knocked over halfway through the print. If you zoom in on the top left side, you can see the blob of PETG that was deposited by the nozzle and which was responsible for this object being dislodged from the bed.
PETG has to be thoroughly dried and both flow and PA have to be carefully calibrated if you’re printing objects like this that can easily be knocked down. You can afford to be less precise with tuning if it’s a big object with a lot of contact with the build plate.
My first attempts to use PETG were all failures - poor adhesion, spaghetti, stringing, and blobs.
Cured all the problems with drying, and calibrating temperature (needed more nozzle heat), flow and pressure advance. Never found a need to mess with z offset.
Door is usually open for PLA, PETG, and TPU, except in winter when the shop temperature is 55-60°F (13-16°C). Then I preheat my X1C with the heat bed to get the chamber up above 25°C, then open door or top if the temp goes above 35°C.
This sounds like the exact issue I was having the first time I tried printing PETG. I cleaned the bed twice. Once with denatured alcohol. I’m brand new to the 3D printing world and thought I was printing PLA. I had picked a box off the shelf at the store that was in with the PLA. I didn’t realize it was PETG. I brought a sample of my spaghetti print to the store, and the nice man in the printing department told me to check my temperatures. I wasn’t using Bambu filament so the AMS didn’t have a barcode to read. Long story short, once I bumped the temperature to what was printed on the filament spool, the part printed beautifully.
