What bed type are you using? The high temp PEI bed seems to have the best adhesion for ABS.
I find one of the key points to stop ABS from warping is to let the chamber heat up. Set the bed to 100, turn on the aux fan and home the machine (so the bed comes to the top). Let this sit for 15ish minutes. The P series doesn’t have a chamber temp sensor but a simple work around is to check the what the nozzle temp is in Bambu Studio. When the nozzle isn’t on it will follow pretty closely to what the chamber temp is at. You can also add a stand alone temp display that is viewable via the onboard camera.
The warmer chamber temp will well help stop any warping. Also make sure you don’t have the chamber or aux fan on during printing. Make sure the top is on and the door remains closed.
A brim (with 0 Brim-object gap) around problematic parts will work much better than a raft in my experience.
ASA and ABS both shrink significantly as the extruded plastic cools off. Higher layers pull “inward” on the edges of the print as they cool, and since plastic is “plastic” (flexible), that inward force generated by higher layers pull up on the layers below and the print’s edges lift up and curl in (“potato chipping”).
To minimize this effect, you need to get the build chamber nice and toasty warm before you start your print (like: turn no the bed heater and wait 30-40 minutes. I run the Aux Fan on high while performing this pre-heat). You also want to max-out the build plate temperature and run the extruder temp at the lowest temp you can use and still get good extrusion and intra-layer adhesion (which may require some experimentation).
If the temperature of the extruded plastic is lower and the temperature of the build plate/chamber is higher, there is less of a delta between the molten plastic’s temperature and the cooled-off extruded plastic, which reduces the “shrinkage” stress that results from cooling, which reduces the forces that pull in/up on the edges of the print that result in warping.
Ditto what was said above
Personally I move the build platform to the bottom for preheating the chamber without the use of the AUX fan but that just a matter of preference.
The default ABS filament profile works OK but as was stated above change the Brim object gap to 0.0mm and also increase the Brim width to 8-10mm.
If you use and only have the textured PEI sheet that came with the P1S make sure it is clean clean clean and even more clean, if it fails up the bed temp to 100C and if it still fails then you may try applying a thin ABS-Acetone slurry coat but that’s rather messy.
Once it’s done printing leave the doors and lid closed and wait until the chamber and part(s) within slowly cooled down to room temp.
Also note that if you are attempting dimensionally functional parts then you may have to resize the part(s) in the X&Y direction to compensate for the material shrink.
I resize to about 100.6% on both X&Y as a baseline but results will vary with part geometry, filament brand and parameters used.
If you are designing a functional part, if you have long/high walls, put holes through them. i.e. the overall tension/shrinkage in a solid wall, say 100mm long, will be more than in a wall made out of say five lengths with gaps in between.
Be careful recommending ABS slurry for use on PEI beds as it’s know that Acetone can degrade PEI. Bambu specifically recommends not using Acetone on bed.
Do not clean the Textured PEI with Acetone, as it will damage the PEI surface.
Yes you are right I should put a disclaimer use at your own risk with that. PEI is generally resistant to Acetone however that resistance is significantly reduced when the PEI surface is hot when in contact with the unevaporated acetone solvent and also one should not soak it with Acetone or Acetone-ABS slurry as prolonged solvent exposure can cause embrittlement of the PEI.
Does the use of glue stick also help with warping? Fighting warping on larger prints even with a pre heat and brim but have not tried a glue stick yet.
For me turning off Auxiliary Cooling Fan and raising bed temperature to 100 degrees prevents warping. My part cooling fan is set to go from 10% to 45% for layers from 30s to 3s (and is off for first 3 layers).
