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Editors:

Marcin Jakubowski

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Graphic Design:

Jean-Baptiste Vervaeck

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Version:

Date:

3D Printer Extruder Design

v19.05

First Edition

Open Source Ecology Design Guide Series

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3D Printer Extruder Design - Table of Contents 1

Summary – How to design an optimal extruder – the heart of a 3D printer. Optimized design for filament access and short filament path, and scalable heater blocks. Simple extruder. Non-threaded heat breaks and nozzles for advanced design. Why nobody does this. Material deposition rates. Applications – If we build a large printer, we may want to design our own extruder because the available ones are not big enough and they have parts that cost $100 for a 25 cent piece of machined aluminum. If we understand how to design an extruder, we can build one at low cost. We can also design different extruders for specific applications. For example, there is currently no commercially available 2.85 mm extruder for printing soft rubber.

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  1. Filament Extruder Design
    1. General Design features
    2. Direct drive vs Indirect drive (Bowden)
    3. Pellet-based extruders and extension to filament making
      1. The Trash Extruder for 3D Printing
    4. Other extruders: metal, paste, ceramic paste
  2. Principles and Design Concepts
    • How it works
    • Why it works
    • The Open Source Wire Feeder: - plastic, wire, etc.
    • Composite extrusion: wire or fiber embedding in plastic
    • Clamped vs screwed extruder design
    • Short feed distance - going neckless
    • Scalability of heater, filament, and drive
  3. Components of a plastic extruder
    • Stepper motors
    • Gearing and pushing force requirements
    • Drive gear and drive mechanism
    • Heat Sink
    • Heat Break
    • Heater block
  4. Scalability

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3D Printer Extruder Design - Table of Contents 2

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  • Scalability
    • Multiple blocks
    • Multiple heater elements with single block
    • Larger filament size from the open source filament maker
    • Cooling
    • Heating and heat loss calculations
      • Conduction in metal and between metal-air
      • Convection
      • Radiation
  • Designing an Optimal Plastic Extruder
    • Optimal Design Checklist
    • Choosing Stepper motors
    • Wire/filament feeder
      • Drive gear for metal and plastic
      • size and shape of drive wheels
      • 1 or 2-sided drive
      • Other applications: Welding and alloying
    • Heat sink design
    • Heat break design
    • Heater block design
    • Heat block insulation
    • Nozzle design
    • Thermistor design
    • Marlin configuration for the heating system
    • Carriage mounting
    • OSE Extruder Part Library
    • Performing basic calculations
    • Thermal Design Workbench in FreeCAD

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3D Printer Extruder Design - Table of Contents 3

  • Scalability
    • Multiple blocks
    • Multiple heater elements with single block
    • Larger filament size from the open source filament maker
    • Part Cooling
    • Heating and heat loss calculations
      • Conduction in metal and between metal-air
      • Convection
      • Radiation
  • Designing an Optimal Plastic Extruder
    • Optimal Design Checklist - Design Rationale
    • Choosing Stepper motors
    • Drive gear size and shape
    • 1 or 2-sided drive
    • Heat sink design
    • Heat break design
    • Heater block design
    • Heat block insulation
    • Nozzle design
    • Thermistor design
    • Marlin configuration for the heating system
    • Carriage mounting
    • OSE Extruder Part Library in FreeCAD
    • Performing basic calculations
    • Thermal Design Workbench in FreeCAD
  • Designing an Optimal Plastic Filament Maker Extruder
    • Simple Extruder
    • Shredding - the open source hydraulic shredder
      • Comparison to electric shredders and slow shredders
      • Particle size
    • Auger size and drive; temperature lockout; breaker plate
    • Designing and sourcing heater elements
    • Overall thermal design: hot and cold parts
    • Product Ecology: Heater control with the RAMPS Universal Controller
    • Material feed and Hopper
    • Puller and Winder

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3D Printer Extruder Design - Table of Contents 4

  • Building a 3D Printer Extruder
    • William :
      • Milling and drilling small aluminum with the D3D CNC Circuit Mill
    • Fasteners used
    • Mounting on a carriage
    • Wiring considerations
    • General workflow - 3D printing, milling, drilling, fasteners, electrical components
    • Wiring to the RAMPS controller
    • Overall build checklist - testing and building steps
    • Quality Control - critical points
  • Testing
    • Retraction testing protocol
    • Determining the heating limit
    • Feed rate testing
      • How to determine as a function of heating power
      • Filament speed: limits before backing up
      • Dependence on nozzle size
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    • Steps/mm testing
    • Testing nozzle with flexible materials

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Notes On Using this Guide

OSE work builds upon these great open source projects:

ABOUT: This is part of a design series on general machine design aimed at basic competency in the design of all 50 Global Village Construction Set machines.

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HOW TO USE: You can use a QR code reader to scan the bar codes to access content online.

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COLLABORATION: This is a collaborative effort. You are invited to help edit this guide. You can edit this document or make a copy, make your edits, and email us describing your proposed changes. To join our open source product development effort, join our Developer Team, or get hands-on experience in our Workshops. Email us at info@opensourceecology.org

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  1. The Trash Extruder

By Sam Smith

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This is the most potentiallly economically significant open source trash https://hackaday.com/2019/06/19/trash-printer-directly-uses-recycled-plastics/