Reprap Darwin

RepRap version 1.0 (Darwin)

The RepRap Project is an initiative aimed at creating a largely self-replicating machine which can be used for rapid prototyping and manufacturing. A rapid prototyper is a 3D printer that is able to fabricate three dimensional artifacts from a computer-based model. Project authors describe 'self-replication', understood as the ability to reproduce the components necessary to build another version of itself, as one of the goals for the project. It is self-replication that distinguishes the RepRap Project from the similar Fab@Home project.

Due to the potential self-replicating ability of the machine, authors envision the possibility to cheaply distribute RepRap units to people and communities, enabling them to create (or download from the internet) complex products and artifacts without the need for expensive industrial infrastructure. They further speculate that the RepRap will eventually demonstrate evolution in this process as well as being able to increase in number exponentially. This, in theory, would give RepRap the potential to become a powerful disruptive technology, similar to that of other anticipated low-cost personal fabrication technologies.

Intentions Edit

The stated goal of the RepRap project is not to produce a pure self-replicating device for its own sake but rather to put in the hands of individuals anywhere on the planet, for a minimal outlay of capital, a desktop manufacturing system that would enable the individual to manufacture many of the artifacts used in everyday life. The self-replicating nature of RepRap could also facilitate its viral dissemination and may well facilitate a major paradigm shift in the design and manufacture of consumer products from one of factory production of patented products to one of personal production of unpatented products with open specifications. Opening up product design and manufacturing capabilities to the individual should greatly reduce the cycle time for kaizen improvements to products and support a far larger diversity of niche products than the factory production run size can support[1].

From a theoretical viewpoint, the project is attempting to prove the following hypothesis:

Rapid prototyping and direct writing technologies are sufficiently versatile to allow them to be used to make a von Neumann Universal Constructor. [2]

Background Edit


First part ever made by a Reprap to make a Reprap, fabricated by the Zaphod prototype, by Vik Olliver {2006/09/13}

Dr Adrian Bowyer, a Senior Lecturer in mechanical engineering at the University of Bath in the United Kingdom, founded and invented RepRap, and leads the project team.[3] The project itself uses additive fabrication, and will make the results available under the GNU General Public License, a free software license, at no cost, allowing other investigators to work on the same idea and improve it.

Currently, low-end commercial 3D prototypers cost about US$49K (from Z Corporation) and you still need to buy materials and solidifiers, which cost a further $1.5K. Prototypes made by these low-end commercial machines cost around US$2 per cubic centimeter to fabricate. And they cannot make themselves. The RepRap Project is on track to produce a 3D prototyping machine and free/open source accompanying software that costs about US$400 to build and which can fabricate objects at a cost of about US$0.02 per cubic centimeter. And it is on its way to universal construction (meaning it creates itself too).

Timeline Edit

First replication

All of the plastic parts for the machine on the right were produced by the machine on the left. (Adrian Bowyer (left) and Vik Olliver(right) are members of the RepRap project.)

  • 13 September 2006 - The RepRap 0.2 prototype successfully printed the first part of itself which was subsequently used to replace an identical part originally created by a commercial 3D printer.
  • 9 February 2008 - RepRap 1.0 "Darwin" had successfully made at least one instance of over half its total rapid-prototyped parts.
  • 14 April 2008 - Possibly the first end-user item is made by a RepRap - a clamp to hold an iPod securely to the dashboard of a Ford Fiesta.
  • Throughout May 2008 - Many more useful objects were made by various first-generation RepRaps - including a coathook, a pair of sandals, a door handle and a fly swatter.
  • 29 May 2008 - Within a few minutes of being assembled, the first completed "child" machine made the first part for a "grandchild" at Bath University, UK.
  • As of 23 September 2008, at least 100 copies had been produced in various countries. The exact number of RepRap in circulation at that time was unknown.[4]

Current status Edit

A short production run (~1 km) of 3 mm polycaprolactone filament suitable for use in the Mk II extruders used in several operational and near-operational reprap prototypes has been produced for the project. With 1km of polycaprolactone filament, the project has been able to produce larger artifacts and also test the candidate systems for days instead of for hours, as was the case with hand-produced filament.

Vik Olliver's Zaphod prototype has replicated a parts set for the Mk II extruder. Vik assembled the parts into a working Mk II and has successfully employed it as a second extruder on Zaphod. The use of polycaprolactone for the parts set instead of ABS required that several minor changes be made when assembling them into a working Mk II.

Hardware development Edit


Mk II polymer extruder (created by Dr. Adrian Bowyer).

While the RepRap project was formally launched in March 2005, the rate of hardware development exploded after the development of the Mk II polymer extruder by Dr. Bowyer in November 2005.[5] The Mk II represents a major advance in the state-of-the-art in that it can operate in a room temperature environment rather than a closed box heated to a temperature just short of the melting point of the polymer being extruded. This greatly reduces both the cost of producing a system and makes specifying materials used in such systems much less critical.

Full RepRap prototypes Edit

Originally assembled in February 2006, as of 10 May 2006 the first full prototype replicator, RepRap 0.1, designed by Vik Olliver in New Zealand, soon began to extrude forms. By mid-July objects of up to 15 layers in depth and 50 mm in diameter were extruded by Da Witch, Vik Olliver's prototype RepRap machine.

The polymer components of the 3D positioning system and polymer extrusion head were created using a commercial additive fabrication machine. The system was subjected to intensive shakedown exercises by Vik Olliver and Simon McAuliffe to integrate the software, firmware and hardware components.

As of September 2006 Da Witch has been rebuilt to make it portable and a second extruder head has been added. The modified RepRap 0.2 has been dubbed Zaphod. Vik Olliver has delivered a lecture about and demonstration of Zaphod and the RepRap research programme in Vienna at the Paraflows 2006 digital arts congress there during 9 September 2006 – 16 September 2006.

RepRap's prototype self-replicating 3D printer, Zaphod, has recently created a full set of the plastic parts needed to make its own extruder.[6]

Other prototypes Edit

Other full prototypes at various stages of development are presently being built by Sells and Bellmore.

To date virtually all RepRap prototypes have been repstrapped. Vik Olliver's prototype, which has evolved into RepRap 0.2, began largely as an assembly of Meccano parts, and to give a notion of the range of materials that can be utilized the bootstrapped prototype, Tommelise[7], is almost entirely built of milled poplar.[8]

The materials chosen reflect local conditions and the skillset that the individual team member brings to the project.

Software development Edit

All 3 axes fdmd sml

RepRap 0.1 prototype (created by Vik Olliver).

RepRap has been conceived as a complete replication system rather than simply a piece of hardware. To this end the system includes computer-aided design (CAD) in the form of a 3D modeling system and computer-aided manufacturing (CAM) software and drivers that convert RepRap users' designs into a set of instructions to the RepRap hardware that turns them into physical objects.

The RepRap team has, for now, identified the free and open-source Art of Illusion (AoI) 3D modeling system as the front end for the RepRap system. AoI is well-suited for this role both because of its power to model 3D objects and because it is written in the popular, portable Java programming language. The basic AoI modeling platform is being tailored to the special needs of the RepRap project via scripts.

Work on RepRap's CAM system also being written in Java is currently in an advanced state of development. That work is being pursued by both Simon McAuliffe and Adrian Bowyer and is being tested as part of the RepRap 0.1 shakedown exercises.

Materials Edit

Extrusion of hexagon 2nd layer closeup

RepRap 0.1 building an object

RepRap will have multiple extruders for applying various materials in the creation of parts.

Potential structural materialsEdit

  • Thermoplastic polymer — which is what is being concentrated on currently. This is generally used to create structure. Polylactic acid has been successfully implemented by at least two project researchers, and will likely become the official polymer of choice. Its positive engineering attributes include its translucent color, minimal warping on cooling and high strength. In addition, unlike most thermoplastics it is not a petroleum-derived product, and thus is theoretically capable of being produced from waste biomass and biodegrading. However, this process only occurs at a significant rate when the thermoplastic is exposed to sustained temperatures above 70°C, so this is not a barrier to its use in printed objects.
  • Ceramic slurries — to create very hard and strong ceramic structure. Silicon nitride is currently being contemplated in this role, though several similar refractories are being considered.

Potential support structure materials includeEdit

  • Plaster/cellulose mixes — can be washed away from the finished product with lukewarm water.
  • Icing sugar — can be washed away from the finished product with lukewarm water.
  • Polycaprolactone/marble dust mixes — can be peeled away from the finished product.

Silicone polymer has been proposed for gaskets, seals and flexible parts.

Electroconductive materialsEdit

  • Wood's metal or Field's metal — low-melting point metal alloys (lower than the melting point of the plastic) to incorporate electrical circuits into the part as it is being formed.
  • Silver-filled polymers — are commonly used for repairs to circuit boards and are being contemplated for use for electrically conductive traces.

Chocolate has been proposed as a whimsical extruded material. This could allow the manufacture of complex 3D Easter eggs and other such items.

Limitations of self-replicationEdit

Although it appears likely that RepRap will be able to autonomously construct much of its mechanical components in the near future using fairly low-level resources, it would still require an external supply of several currently non-replicable components such as sensors, stepper motors or microcontrollers. A certain percentage of such devices will have to be produced independently of the RepRap self-replicating process. The goal is, however, to asymptotically approach a 100% replication over a series of evolutionary generations. As one example, from the onset of the project the RepRap team has explored a variety of approaches to integrating electrically conductive media into the product. Success on this initiative should open the door to the inclusion of connective wiring, printed circuit boards and possibly even motors in RepRapped products[9]. Variations in the nature of the extruded, electrically conductive media could produce electrical components with different functions than pure conductive traces not unlike what was done in John Sargrove's sprayed-circuit process of the 1940s (also known as Electronic Circuit Making Equipment or ECME).

Project members Edit

Turntable with 5v psu

Meccano repstrap of RepRap 0.1 prototype (created by Vik Olliver).

  • Sebastien Bailard, in Ontario.
  • Brett Bellmore in Michigan.
  • Dr. Adrian Bowyer, Senior Lecturer in the Mechanical Engineering Department University of Bath.[3]
  • Michael S. Hart, creator of Project Gutenberg, in Illinois.
  • Dr. Forrest Higgs, Brosis Innovations, Inc. in California.
  • James Low, undergraduate in the Mechanical Engineering Department at the University of Bath.
  • Simon McAuliffe in New Zealand.
  • Vik Olliver, Diamond Age Solutions, Ltd. in New Zealand.[10]
  • Ed Sells, postgraduate in the Mechanical Engineering Department at the University of Bath.
  • Zach Smith, in the United States.

Sponsors Edit

  • Reece Arnott
  • The Bath University Innovative Manufacturing Research Centre[11]
  • The Engineering and Physical Sciences Research Council[12]
  • The Fluorocarbon Co. Ltd.[13]
  • Michael Ingram
  • Lukasz Kaiser
  • The Nuffield Foundation
  • Carl Witty

References Edit

See also Edit

External links Edit

Project websitesEdit


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