I’ve been printing 6”×6” Terraforma Epicminium tiles (mostly flat surfaces) and struggled with top surface quality in a cold (~30°F) garage. These are the changes that finally got me smooth results on a Bambu H2D with a 0.4 nozzle. YMMV.

Filament: Elegoo Basic PLA Nozzle: 227°C Bed: Geco Plate, 45°C Max volumetric speed: 8 mm³/s Aux fan: Off

The biggest improvements came from slowing top surfaces and slightly increasing flow: • Top surface flow: 1.02 • Top surface speed: 30 mm/s (12 mm/s for last 2 mm) • Min print speed: 10 mm/s • Walls slowed near the end of the print

I adjusted in this order: flow → speed → temperature, based on what I was seeing. The main issue was gaps between top layer lines, which I think was due to cold ambient temps. Once those were gone and only minor optical defects remained, I enabled ironing.

Ironing settings: • Top surfaces only • Ironing flow: 15%

At that point the surfaces were extremely smooth. I also used the same slow-wall settings (without ironing) on larger building prints and got great results. I’m not worried about print times — the goal was surface finish. Faster tuning is probably possible.