04-21-2022: Ultimaker released Cura 5.0, powered by the Arachne engine
Ultimaker claimed it had finally solved the thin-wall problem in FFF 3D printing
On April 21, 2022, Ultimaker launched Cura 5.0—software that was the result of over a year of work on an entirely new slicing engine called Arachne. It was promoted as the biggest leap in print quality the software had ever achieved.
At first glance, the differences seemed minor—visually, very little had changed. Cura introduced a new icon design and updated its loading screen graphics. The interface became more streamlined, with subtler icons for a cleaner look. A significant change for Ultimaker printer users was the introduction of new printing profiles. According to the company, the updated algorithms made print times up to 20% faster compared to Cura 4.x.
But the real breakthrough lay in how the new engine handled gaps within 3D prints. FFF 3D printers have long struggled with printing thin walls. Standard nozzles typically have a diameter of 0.4 mm, which also defined the width of the extruded material. It was difficult—if not impossible—to print paths much thinner or wider than this. Until then, the problem had been largely ignored.
The previous Cura engine handled a 4.4 mm-wide area by slicing four 1.0 mm lines, leaving a 0.4 mm gap that was often impossible to fill properly. The Arachne engine introduced variable line width. Instead of fixed-width paths, it adapted each extrusion—printing four lines at 1.1 mm to perfectly fill the space. This adaptive line width reduced internal gaps in printed parts, resulting in stronger and more solid components.
The greatest improvement in part strength was seen when printing thin walls, which previously suffered from structural weaknesses due to internal voids caused by fixed-width lines.
According to Ultimaker, the improved thin-wall handling in Cura 5.0 brought FFF-printed parts significantly closer to the strength and quality of injection-molded parts.
The latest version of Cura as of now is 5.10.0, released in March 2025.
Source: www.youtube.com
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