Printing Smooth Upper Surfaces with a Non-Planar Slicer

One of the most tantalizing prospects for 3D printing has been non-planar printing, which promises smoother surfaces without a staircase pattern, reduced support structures, and potentially greater strength. The lack of non-planar slicer programs has been a major limitation to its adoption, a gap which Zimeng Xiong of Alpaca Engineering has worked to eliminate with PancakeSlicer.

Printer Compatibility

PancakeSlicer is designed to work with standard 3-axis printers, such as the Bambu Labs A1 Mini. The non-planar paths available are limited by the print head's clearance on each side of the nozzle. This can be improved by removing the cooling shroud and using a remote static cooling system that blows cooling air from the sides of the print bed.

Slicing Method

The software first identifies surfaces where the top layer should be smoothly overlaid by tracing rays downward through the part. The simplest approach generates a planar structure with non-planar layers on top, though this can leave some staircase pattern. A morphed structure continuously varies layer thickness to eliminate this issue, though narrow regions may become too thin for proper extrusion.

Conformal slicing solves this by building a planar base, a morphed transition region, and several constant-thickness conformal layers on top. Where the slicer can't print non-planar layers due to print head clearances, it falls back to planar slicing.

Current State

While a universal non-planar slicer is still awaited, there have been remarkable advances in recent years, including non-planar print ironing, infill, and conformal overlays. Some enthusiasts have even modified home-built printers with fourth and fifth axes to expand non-planar printing capabilities.