Hi there,
just woke up and had a look after my 23 hours print (Part of the AMS-Riser) and was shocked! It seems as if the printer forgot to print the outer walls? I used Bambu Lab PETG Basic- never had any problems before…
Even the spaghetti-detection didn’t work.
Does anybody may have an idea what went wrong?
Would be really happy if anybody could help! - waisted ~ 500 g of filament 
greetings kuhni
Did you slice the model, or was it printed from makerworld with someone else’s print profile?
That’s a great question. If the Makerworld 3MF was set to PLA, you would get exactly this result. Ask me how I know? Well… since you asked… 
This is exactly what happened to me with fully dried Bambulab PETG but I had overlooked the filament and left it to PLA. Does this result look familiar?
As you might notice, I caught the problem early enough and stopped the print but what a mess. 
Via AMS? If so, Interesting, curious when you sent it and I presumed chose the AMS slots in the final screen, that the RFID would have read the PETG , and gone hang on - slicer wants PLA - “are you sure” etc. Woudlnt help non RFID filaments… but … hey an idea right?
No AMS. This was just a naked spool on the back of a P1P. This purely a self-inflicted cockpit error. I can’t blame the tech, this one was all me I’m afraid. 
Subsequent print immediately after I cleaned off the plate was perfect. Same spool too.
I sliced it. Everything looked finde… The first layer is perfect…
Just had a look again (downloaded the model as 3mf from the printer as the origin file was already closed / deleted):
The temperature is set to 255 (corresponding to the PETG-temp).
Regarding the speed it printed quite fast… So is there maybe a problem with the slicer? But also if I reslice it- it shows almost the same settings…?
I don’t really like the look of that sliced file. It looks like it’s been “optimised” to print very fast but likely could be your issue. A bit hard to see on my phone but it looks like it only has one wall? and relatively high percentage gyroid infill and very high speeds being mostly green. I’d reslice with 0.20mm layer height, 3 walls and 20% infill, 4 or 5 top and bottom layers, which is basically the standard 0.20 strength profile. More walls is stronger than more infill percentage. And just try loading your standard Bambu PETG filament profile.
The issue appears to be flow-related. Either the print head is moving too fast for the filament flow rate, or the extruder isn’t flowing correctly. Since it’s BBL filament, the flow rate should be “good”, which suggests a problem with the extruder - either the drive wheel is loaded up and slipping or the stepper isn’t always stepping when it should.
I never go above 80 mm/s with PETG. Looks like your speed is just way too high.
The infill is 15%. 3 walls, 5 bottom layers, 8 top layers. The layer height is set to 0.12 to get a smoother finish. The profile I used is the standard Bambulab PETG Profile. I only “changed” the Flow ratio as I calibrated the filament…
But why should this happen? The machine is likely out of the box, only 3 weeks old…?
I was referring to the Bambu-Lab settings. I think if they sell filament and claim to have optimized it, I don’t think I should e.g. change the speed.
just thought about something: I sliced the part using 0.12 mm layer height. The max volumetric speed for the Bambu PETG is set to 13 mm³/s. But if you ar printing at a lower layer height, less filament is used per printed mm- so the speed increases. As PETG is only rated for max 200 mm/s print speed, maybe the 13 mm³/s is to high as there are print speeds >200 mm/s achieved with this profile?
Sometimes you get the “short straw”. I’m hoping your machine isn’t actually busted, but no manufacturer ships 100% of their product 100% free of defects. Someone invariably will end up with a machine that malfunctions shortly after they start using it. An unlucky few might end up with a machine that doesn’t work at all, right out of the box.
I only “changed” the Flow ratio as I calibrated the filament…
What are the settings you used for temp, flow and PA?
Agree, that definitely looks like under extrusion that I’ve seen due to excessive flow. OP, could you check the flow of the outer walls? You could use the flow option from the dropdown in the preview.
I found that on default temperatures, my roll of generic PETG starts underextruding at flows of around 22mm^3/s. However, I noticed that by increasing the temperature to 300 degrees, I could print at up to 30mm^3/s without any flaws and with no perceivable difference in layer adhesion. Your mileage might vary, especially with overhangs and surface detail, but this might help if you’re looking for truly ludicrous speeds
