My arch ceiling doesn't go well

Hi everyone,

I’m quite new to 3D printing and recently got a P2S printer. I’ve been trying to print an arch, but the ceiling/upper surface of the arch doesn’t come out smooth most of the time. I’ve printed several attempts and only one of them had a smooth ceiling.

Here are the settings and adjustments I’ve tried so far:

• Using Auto Tree Supports
• Outer wall speed: 30 mm/s
• Inner wall speed: 130 mm/s
• Enabled Detect Small Walls (there is text on the other side of the model)
• Reduced inner wall width from 0.45 mm to 0.38 mm
• Enabled Ironing on top surfaces

If I enable ironing for all solid layers, the print time increases by about 3x, which I’d prefer to avoid if possible.

Forgot to mention, the arch is like 8 cm high.

Does anyone have suggestions on what settings I could adjust to get a smoother ceiling on the arch? Any tips would be really appreciated.

Thanks in advance!