---
title: "Wave-based toolpaths enable support-free horizontal overhangs in extrusion 3D printing"
url: https://www.voxelmatters.com/wave-based-toolpaths-enable-support-free-horizontal-overhangs-in-extrusion-3d-printing/
date: 2026-06-16
modified: 2026-06-14
lang: en
author: "Davide Sher"
description: "Horizontal overhangs have long been treated as unprintable on standard 3-axis FDM systems without sacrificial support structures. A new path-planning strategy published in Additive Manufacturing Letters challenged that assumption. Researchers..."
categories:
  - "3D Printing Processes"
  - "AM Research"
  - "Research & Education"
tags:
  - "future"
image: https://www.voxelmatters.com/wp-content/uploads/2026/06/test_1-e1781472648332-640x424.png
word_count: 655
---

# Wave-based toolpaths enable support-free horizontal overhangs in extrusion 3D printing

Horizontal overhangs have long been treated as unprintable on standard 3-axis FDM systems without sacrificial support structures. A new path-planning strategy published in Additive Manufacturing Letters challenged that assumption. Researchers Janis Andersons, Salomé Sanchez, and Tom Vaneker developed a method that generates toolpaths based on wave propagation theory, enabling fully cantilevered 90° overhangs to be printed support-free on unmodified desktop hardware—with significantly less sagging than previous approaches. Their paper [was published in ScienceDirect's Additive Manufacturing Letters](https://www.sciencedirect.com/science/article/pii/S277236902600040X?via%3Dihub).

The conventional limit arises from how filament extrusion deposits material: each semi-molten track must touch the layer below to avoid collapsing, which limits printable overhang angles to about 45° under typical parameters. The standard workaround, sacrificial support structures, wastes material and print time, requires manual removal, scars downward-facing surfaces, and rules out geometries where supports cannot be cleared, such as internal cavities.

## Waves over arcs

The new strategy builds on the principle of laterally supported overhangs, in which each new track adheres sideways to a previously deposited and solidified track rather than resting on the layer beneath. Earlier implementations of this idea encountered limitations. Contour-based paths, demonstrated by Fazzini et al., fail on concave shapes, while the "arc overhang" technique developed by Steven McCulloch handles arbitrary shapes but produces systematic sagging around the nuclei of its recursive arcs, where short segments cannot cool in time.

The researchers instead traced paths as wavefronts, following the Huygens principle, where every point on a wavefront acts as the source of secondary wavelets that recombine to form the next wavefront. Each printed path is spaced at a fixed distance from the previous one, ensuring lateral overlap, while the long, continuous wavefronts give prior tracks time to solidify. Because waves naturally diffract, the paths bend smoothly around corners, holes, and narrow sections—the failure points of earlier strategies. The team implemented the algorithm in Grasshopper, with extrusion rates calculated using a volume-equivalence approach decoupled from the nominal layer height.

## Shining a light

To validate the method, the team printed cantilevered monolayer overhangs of three difficulty levels in PLA on a Bambu Lab A1 mini, compared wave paths directly with arc paths under identical parameters, and characterized sagging using structured-light 3D scanning on a Shining 3D EinScan Pro 2X. At easy and medium difficulty, the two strategies performed comparably, but at the hardest shape—which includes a concavity—the wave paths reduced the standard deviation of surface deviation by 49% to 66% and maximum sagging by 30% to 48%. The arc samples also showed systematic gaps in coverage at the hardest difficulty; the wave samples showed none.

A multilayer demonstrator confirmed that subsequent layers can be deposited reliably onto wave-path overhangs to build complete volumetric parts. Compared to an identical part printed with conventional supports, the wave-overhang version showed comparable dimensional accuracy and used 39% less material, though the print time was 72% longer due to the conservative 2 mm/s overhang printing speed. Four additional demonstrators — a flanged bracket, a counterbore, a snap-fit bracket, and a hollow cube with holes on each face — illustrated common industrial geometries that would otherwise require difficult or impossible removal of support.

![Explore support-free overhangs and revolutionary printing methods that allow 90° cantilevered structures on standard FDM systems.](https://www.voxelmatters.com/wp-content/uploads/2026/06/nosupports_1-s2.0-S277236902600040X-gr1.jpg)The authors noted several open questions: the maximum achievable span, upper speed limits, part strength in the overhang region, and behavior across materials were not yet characterized. Thermal warping caused slight upward curling at overhang edges, an effect expected to worsen with higher-CTE engineering polymers such as ABS, PC, and nylon.

## Enabled by open-source slicers

The strategy has already moved beyond the lab. It has been implemented in forks of two popular open-source slicers—[a PrusaSlicer fork maintained by McCulloch](https://github.com/stmcculloch/PrusaSlicer-WaveOverhangs), the creator of the original arc overhang technique, and an [OrcaSlicer fork by Dennis Klappe](https://github.com/dennisklappe/OrcaSlicer-WaveOverhangs), which handles overhang detection and wave path generation automatically and also supports angled, not just horizontal, overhangs. The paper, published open access, suggests that some printability constraints long treated as physical limits of filament material extrusion may in fact be artifacts of conventional path planning.