3D printing issu : vertical walls are not straight

1

Hi everyone,
I’m having an issue on all my 3D prints with my Bambu Lab A1. Whenever a model has a vertical wall that ends with a flat horizontal surface, the walls tend to deform/lean instead of staying straight (see photos). i trying on teh Bamabu lab A1 of a friend and i have the same problem, but my setting seems ok and I use hairspray to agood adesion.
My current settings are:
Layer height: 0.16 mm
3 walls
10% Gyroid infill
Brim at the bottom
I use standard PLA (210–240°C) and i print it at 220 degrees

I can’t seem to get perfectly straight vertical walls. Has anyone experienced this issue or have any suggestions on what I should change?

Thanks in advance! :slight_smile:

WhatsApp Image 2026-08-08 at 01.28.46 (1)
WhatsApp Image 2026-08-08 at 01.28.46 (1)1200×1600 83.7 KB

WhatsApp Image 2026-08-08 at 01.28.46
WhatsApp Image 2026-08-08 at 01.28.461200×1600 140 KB

2

Make sure the “print outer wall first” setting is set to outer. Should be in the Quality tab under walls and surfaces. It might help.

3

Vertical walls not staying is usually caused by one of these issues: mechanical alignment, slicer settings, cooling/shrinkage, or extrusion problems.

  1. Check mechanical alignment first
    1. make sure the X/Y/Z axes are square and the frame is rigid.
    2. check belt tension
    3. Inspect Z lead screws / rods for bends and ensure Z couplers are tight but not over-estimated.
  2. Review slicer settings
    1. reduce outer wall speed and overall print speed.
    2. enable/adjust pressure advance or linear advance if your firmware supports it
    3. check acceleration/jerk: too high can cause ringing too low can cause oozing at concerns.
    4. For materials like PETG/ABS try printing outer wall before inner wall and reduce top-infill overlap.
  3. Manage cooling and shrinkage
    1. for LPA use good part cooling for ABS/PETG, avoid too much direct cooling and consider a warmer ambinet/chamber.
    2. rapid or uneven cooling can make walls bow or lean, especially on tall vertical surfaces.
  4. Verify extrusion
    1. calibrate flow rate / extrusion multiplier
    2. make sure you’re not over-extruding, extra material at corners can push walls outward.
    3. use consistent, dry filament

If you can share printer model, material, layer height, wall speed, and a photo of a calibration cube. That usually make it much easier to pinpoint whether it’s mechanical, thermal, or slicer-related.