# Hybrid FFF/CNC: An open source hardware & software system

## TL;DR

This paper introduces a low-cost hybrid 3D printing and milling system that improves surface quality by combining open-source hardware and software.

## Contribution

A novel hybrid FFF/CNC system using open-source tools and a spindle with a maxwell kinematic coupling for improved surface roughness.

## Key findings

- The hybrid system improves surface roughness parameters by a factor of 10 for most measurements.
- Layer-by-layer hybridization provides better surface roughness due to reduced depth of cut and favorable cutting conditions.
- Surface roughness is uniform in both construction and deposition/machining directions.

## Abstract

This paper presents a low-cost milling system composed of spindle mountable on a multi tool 3D printer equipped with maxwell kinematic coupling (E3D “ToolChanger” in this article) as well as two open-source software solutions for implementing a hybrid FFF/CNC manufacturing process. The first solution is the use of a traditional CAM software (FreeCad) for machining programming through the development of a dedicated post-processor. The second is an automatic layer-by-layer hybridization enabled by the software “SuperSlicer”. This method requires no machining knowledge but only allows contouring operations. Results of experiments show that the spindle presented in this work is capable of successfully carrying out a hybrid process that significantly improves the surface roughness parameters, with an improvement factor of 10 for most parameters. An uniformization of surface roughness parameters was also observed in the construction direction and in the deposition/machining direction. The layer-by-layer hybridization yields the better results in terms of surface roughness. This is because the reduced depth of cut (equivalent to a printed layer) minimizes stress and temperature rise, resulting in highly favorable cutting conditions.