Proud owner of a P1S and recently an A1.
A1 had issues with stringing out of the box. Models and filaments (bambu lab brand - dried) that would work on my P1S were failing with stock settings on the A1. All of my testing was done through Bambu slicer and with moving the same spool of filament between machines while in the same dryer. I would get terrible stringing and eventual collapsing of any sort of complex print jobs on the A1. I tried messing with retraction settings on the A1, with no luck. Also did a ton of cold pulls to make sure I didn’t have a partial clog. Also verified that an “air extrusion” was straight down with no curl. I did see someone else mention that swapping to the 0.4 hardened nozzle helped them, so I went ahead and ordered one even though I only print PLA.
Put the A1 on the shelf for about a week and swapped in the nozzle as soon as it came. Everything was totally fixed. I can print anything on my A1 that I can on my P1S now. I also ordered a 0.6 nozzle that I’ve been having great success with. I do like how the bed “slinging” is quite a bit less with the larger nozzle, as the extrusion is doing more work than the head and bed movement. I’m likely going to go 0.6 on the A1 from now on.
Anyways. Looks like there may be a bad batch of 0.4 stainless nozzles running around. Not sure if anyone else is running into this besides me and the other dude, but it’s worth a shot if you’re having issues.