A frugal CNC Oxyfuel Cutter

An open source CNC gas cutter for resource constrained settings

Cad model of the CNC oxyfuel cutter

Project Overview

This project presents a low-cost CNC oxyfuel cutter designed specifically for metal fabrication microenterprises in Oman. These small workshops often build structural and non-structural items such as gates, staircases, warehouses, and furniture — all requiring the cutting of thick steel plates (3–50+ mm).

Despite the efficiency of automated cutting, CNC machines remain inaccessible to these workshops due to high cost, limited space, and lack of local availability.

Understanding User Needs

A field study was conducted in the industrial cluster of Wadi Kabir Sanaya, Muscat. Most workshops are open-air, compact (15–20 m²), and operated by 2–3 migrant workers from South Asia. Key insights from interviews and observations include:

  • No existing use of CNC or digital fabrication tools
  • Frequent use of handheld oxyfuel torches
  • Cutting done on full or scrap sheets, often outside due to their weight
  • Strong preference for compact, affordable, and stowable machines
  • Limited access to electronics or precision components locally
Interviewing owners and workers from various steel fabrication microenterprises in Oman.

Design Decisions

Why Oxyfuel Cutting?

Among various fabrication processes, gas cutting was selected for automation due to:

  • High repetition of cutting tasks
  • Time-consuming and hazardous manual cutting
  • Poor cut quality requiring extensive post-processing

Frugal, Participatory Design

The machine was designed with end users using a co-design approach whereby the prototype was fabricated within one of the workshops. Workers participated in:

  • Suggesting fabrication methods
  • Design improvements
  • Solving design challenges during assembly for example by co-designing by prptotyping some of the complex sub-assemblies like the Z-axis
  • Assembling the machine frame in the workshop

Local Constraints and Adaptations

  • The machine was built from easily available surplus workshop materials (e.g., 2” square steel tubing)
  • Simple linear guides using locally available roller bearings
  • No reliance on imported machine torches — compatible with users’ own handheld torches
  • Fabrication aided by paper templates for marking and drillingpp

// put picture of the excel sheet of available local material, next to it show the basic hand torch

  • Materials like aluminum and precision linear rails were unavailable or too expensive
  • No access to standard machine parts (e.g., M3 screws), so designs were adapted
  • CAD development followed field sketches and rough calculations

//put picture of the workshop setting, and a drilling picture to show jibg

Key Features

  • Affordable: Target price $500–800 (small shops), up to $3000 (larger shops)
  • Compact: Easily stowable when not in use
  • Safe & Efficient: Reduces risk, labor, and post-processing
  • User-Centric: Designed and built with the microenterprise workers taking local materials and capabilities into account

Prototyping

References

2023

  1. pp1.gif
    Exploring the Potential of Open Source Machine Tools for Sustainable Industrial Development in Low Resource Contexts - A Case Study of Migrant-Run Microenterprises in Oman
    Mohammed Omer, Melina Kaiser, Tobias Redlich, and 1 more author
    In Manufacturing Driving Circular Economy, 2023

2022

  1. pp4.gif
    Democratizing Manufacturing – Conceptualizing the Potential of Open Source Machine Tools as Drivers of Sustainable Industrial Development in Resource Constrained Contexts
    Mohammed Omer, Melina Kaiser, Manuel Moritz, and 3 more authors
    2022