RepRap project

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RepRap version 1.0 (Darwin)
RepRap version 2.0 (Mendel)
Adrian Bowyer talking about the RepRap Project at Poptech 2007
First part ever made by a RepRap to make a RepRap, fabricated by the Zaphod prototype, by Vik Olliver (2006/09/13)

The RepRap project started as a British initiative to develop a 3D printer that can print most of its own components and be a low-cost 3D printer, but it is now made up of hundreds of collaborators world wide.[1] RepRap (short for replicating rapid prototyper) uses an additive manufacturing technique called fused filament fabrication (FFF) to lay down material in layers; a plastic filament or metal wire is unwound from a coil and supplies material to produce a part. The project calls it Fused Filament Fabrication (FFF) to avoid trademark issues with the "fused deposition modeling" term.

As an open design, all of the designs produced by the project are released under a free software license, the GNU General Public License.[2]

Due to the 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 without the need for expensive industrial infrastructure (distributed manufacturing)[3] including scientific equipment.[4][5] They intend for the RepRap to demonstrate evolution in this process as well as for it to increase in number exponentially.[1][6] A preliminary study has already shown that using RepRaps to print common products results in economic savings, which justifies the investment in a RepRap.[7]


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.
Version 2 'Mendel' holding recently printed physical object next to the driving PC showing a model of the object on-screen
Video of RepRap printing an object
RepRap 0.1 building an object
Meccano repstrap of RepRap 0.1 prototype (created by Vik Olliver)

RepRap was founded in 2005 by Dr Adrian Bowyer, a Senior Lecturer in mechanical engineering at the University of Bath in the United Kingdom.

RepRap family tree visualising the evolution of the RepRap and some other 3d printers over time

The first four official 3D printing machines RepRap project were: "Darwin", released in March 2007, "Mendel", released in October 2009, "Prusa Mendel" and "Huxley" released in 2010, although hundreds of variations exist.[8] The core developers have named each after famous evolutionary biologists, as "the point of RepRap is replication and evolution", however, other variants are often named after individual designers or names they prefer.[9]

23 March 2005
The RepRap blog is started.
Summer 2005
Funding for initial development at the University of Bath is obtained from the UK's Engineering and Physical Sciences Research Council
13 September 2006
The RepRap 0.2 prototype successfully prints the first part of itself, which is subsequently used to replace an identical part originally created by a commercial 3D printer.
9 February 2008
RepRap 1.0 "Darwin" successfully makes 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.
29 May 2008
Within a few minutes of being assembled, the first completed "child" machine makes the first part for a "grandchild" at the University of Bath, UK.
23 September 2008
It is reported that at least 100 copies have been produced in various countries. The exact number of RepRaps in circulation at that time is unknown.[10]
30 November 2008
First documented "in the wild" replication occurs. Replication is completed by Wade Bortz, the first user outside of the developers' team to produce a complete set for another person.
20 April 2009
Announcement of first electronic circuit boards produced automatically with a RepRap, using an automated control system and a swappable head system capable of printing both plastic and conductive solder. Part is later integrated into the RepRap that made it.
2 October 2009
The second generation design, called "Mendel", prints its first part. The Mendel's shape resembles a triangular prism rather than a cube.
13 October 2009
RepRap 2.0 "Mendel" is completed.
27 January 2010
The Foresight Institute announces the "Kartik M. Gada Humanitarian Innovation Prize" for the design and construction of an improved RepRap. There are two prizes, one of US$20,000, and another of $80,000. The administration of the prize is later transferred to Humanity+.[11]
31 August 2010
The third generation design, "Huxley", is officially named. Development is based on a miniaturized version of the Mendel hardware with 30% of the original print volume.
First half 2012
RepRap and RepStrap building and usage are widespread within the tech, gadget, and engineering communities. RepRaps or commercial derivatives have been featured in many mainstream media sources, and are on the permanent watch lists of such tech media as Wired and some influential engineering-professionals' news media.[12]
Late summer/fall 2012
There has been much focus on smaller startup companies selling derivatives, kits, and assembled systems, and R & D results into new related processes for 3D Printing at orders-of-magnitude-lower prices than current industrial offers. In terms of RepRap research, the most notable result is perhaps the first successful Delta design, Rostock, which is maturing slowly and has an initial working solution for experimentation by self-sourcing builders of some experience. While the Rostock is still in an experimental stage with major revisions almost monthly, it is also near the state of the art, and a radically different design. The latest iterations use OpenBeams, wires (typically Dyneema or Spectra fishing lines) instead of belts, and so forth, which also represents some of the latest trends in RepRaps.
Hobby friendly machines (e.g. recyclebots) have been made to allow hobbyists and small companies to produce their own filament for 3D printing, thus bringing down manufacturing costs and allowing for small-scale recycling and experimenting with different plastics and materials.
In early January 2016 RepRapPro (the commercial arm of the RepRap project in the UK) announced on their website that they are to cease trading on 15 January 2016. The reason given was congestion of the market for low-cost 3D printers and the inability to expand in that market:

We have decided to close RepRap Professional Ltd.

The company will cease trading on Friday 15 January 2016. We will service all support and warranty requests up to that date, and fulfill all our outstanding orders.

The market for low-cost 3D printers is now so crowded and so competitive that a small specialist company like ours cannot expand. So, because we are not bankrupt and we do not have any debts to pay, we have chosen to stop now while we are ahead and to concentrate on other activities.

Note that our closure does not affect RepRapPro China Ltd. That is a completely separate company (though we have obviously worked closely with them) and they will continue.

We are an open-source company. This means that all our designs, software source-code and documentation are freely available online on our website and on Github. All that information will continue to be available into the future.

We would like to thank everyone who has supported us in the past, either as customers or as contributors who have improved our open-source products, or both. The fact that, unusually for a former company, we will be able to leave megabytes of useful information available to everyone in perpetuity is due in part to the support from those people.

—, accessed 06 January 2016


As the project was designed by Adrian Bowyer to encourage evolution, many variations have been created.[8][13] As an open source project designers are free to make modifications and substitutions, but they must reshare their improvements. However, RepRap 3D printers generally consist of a thermoplastic extruder mounted on a computer-controlled Cartesian XYZ platform. The platform is built from steel rods and studding connected by printed plastic parts. All three axes are driven by stepper motors, in X and Y via a timing belt and in Z by a leadscrew.

At the heart of the RepRap is the thermoplastic extruder. Early extruders for the RepRap used a geared DC motor driving a screw pressed tightly against plastic filament feedstock, forcing it past a heated melting chamber and through a narrow extrusion nozzle. However, due to their large inertia, DC motors cannot quickly start or stop, and are therefore difficult to control with precision. Therefore, more recent extruders use stepper motors (sometimes geared) to drive the filament, pinching the filament between a splined or knurled shaft and a ball bearing.

RepRap's electronics are based on the popular open-source Arduino platform, with additional boards for controlling stepper motors. The current version electronics use an Arduino-derived Sanguino motherboard, and an additional, customized Arduino board for the extruder controller. This architecture allows expansion to additional extruders, each with their own extruder controller.

Major revisions[edit]

The first publicly released RepRap, Darwin, has an XY gantry mounted above a moving Z-axis print bed. Darwin's Z axis is constrained by a leadscrew at each corner, all linked together by timing belts to turn in unison. Electronics are mounted on the steel supports of its cuboid exterior, and on a second platform at the base. In an effort to minimize the number of non-printed components (or "vitamins"), Darwin uses printed sliding contact bearings on all of its axes.

Mendel replaced Darwin's sliding bearings with ball bearings, using an exactly constrained design that minimizes friction and tolerates misalignment. It also rearranged the axes, so that the bed slides in the horizontal Y direction, while the extruder moves up and down and in the X direction. This makes Mendel less top-heavy and more compact than Darwin, while also removing the overconstraint of Darwin's four Z axis leadscrews. The build envelope for Mendel is 200 mm (W) × 200 mm (D) × 140 mm (H) or 8" (W) × 8" (D) × 5.5" (H).

A timelapse video of a robot model (logo of Make magazine) being printed using FDM on a RepRapPro Fisher, a delta-style printer .

One of the more popular RepRap variants from 2013 and beyond is the Rostock delta-style RepRap.[14]


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.

Initially two different CAM toolchains had been developed for the RepRap. The first, simply titled "RepRap Host", was written in Java by lead RepRap developer Adrian Bowyer. The second, "Skeinforge", was written independently by Enrique Perez. Both are complete systems for translating 3D computer models into G-code, the machine language that commands the printer.

Later, other programs like slic3r, pronterface, Cura, repetier host were created. The closed source KISSlicer also seems popular.

Virtually any CAD or 3D modeling program can be used with the RepRap, as long as it is capable of producing STL files.(slic3r also supports .obj and .amf files) Content creators make use of any tools they are familiar with, whether they are commercial CAD programs, such as SolidWorks and Autodesk AutoCAD, Autodesk Inventor, Autodesk 123D Design, Tinkercad, or open-source 3D modeling programs like Blender, OpenSCAD, and FreeCAD.

Replication materials[edit]

RepRaps print objects from ABS, Polylactic acid (PLA), Nylon (possibly not all extruders capable), HDPE, TPE and similar thermoplastics.

Polylactic acid (PLA) has the engineering advantages of high stiffness, minimal warping, and an attractive translucent colour. It is also biodegradable and plant-derived.

The mechanical properties of RepRap printed PLA and ABS have been tested and have been shown to be equivalent to the tensile strengths of proprietary printers.[15]

Unlike in most commercial machines, RepRap users are encouraged to experiment with printing new materials and methods, and to publish their results. Methods for printing novel materials (such as ceramics) have been developed this way. In addition, several RecycleBots have been designed and fabricated to convert waste plastic, such as shampoo containers and milk jugs, into inexpensive RepRap filament.[16] There is some evidence that using this approach of distributed recycling is better for the environment [17][18][19] and be useful for creating "fair trade filament".[20]

In addition, 3D printing products themselves at the point of consumption by the consumer has also been shown to be better for the environment.[21]

The RepRap project has identified polyvinyl alcohol (PVA) as a potentially suitable support material to complement its printing process, although massive overhangs can be made with using thin layers of the primary printing media as support, which are mechanically removed afterwards.

Printing electronics is a major goal of the RepRap project so that it can print its own circuit boards. Several methods have been proposed:

  • Wood's metal or Field's metal: low-melting point metal alloys to incorporate electrical circuits into the part as it is being formed.
  • Silver/carbon-filled polymers: commonly used for repairs to circuit boards and are being contemplated for use for electrically conductive traces.[22]
  • Direct extrusion of solder[23]
  • Conductive wires: can be laid into a part from a spool during the printing process

Using a MIG welder as a print head a RepRap deltabot stage can be used to print metals like steel.[24][25]

The RepRap concept can also be applied to a milling machine.[26]


Other 3D printer designs (such as the commercial Makerbot) and parts constructed by other means (such as Meccano or wood) may be used to "bootstrap" the RepRap process by building RepRap parts. Many such machines are based on RepRap designs and use RepRap electronics. These are generally known by the name RepStrap (for "bootstrap RepRap") by the RepRap community. A RepStrap is any open-hardware rapid-prototyping machine that makes RepRap parts and is itself made by fabrication processes which aren't under the RepRap umbrella yet. Some RepStrap designs are similar to Darwin or Mendel, but they have been modified to be made from laser cut sheets or milled parts. Others, such as the Makerbot, share some design elements with the RepRap (especially electronics), but with a completely reconfigured mechanical structure.

Although the aim of the project is for RepRap to be able to autonomously construct many of its own mechanical components in the near future using fairly low-level resources, several components such as sensors, stepper motors, or microcontrollers are currently non-replicable using the RepRap's 3D printing technology and therefore have to be produced independently of the RepRap self-replicating process. The goal is to asymptotically approach 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. The future success of this initiative should open the door to the inclusion of connective wiring, printed circuit boards, and possibly even motors in RepRapped products. Variations in the nature of the extruded, electrically-conductive media could produce electrical components with different functions from pure conductive traces, not unlike what was done in the sprayed-circuit process of the 1940s named Electronic Circuit Making Equipment (ECME), described in the article on its designer, John Sargrove. Printed electronics is a related approach. Another non-replicable component is the threaded rods for the linear motions. A current research area is in using replicated Sarrus linkages to replace them.[27]

Project members[edit]

The "Core team" of the project[28] has included:

  • Dr. Adrian Bowyer, Former Senior Lecturer, Mechanical Engineering Department, University of Bath
  • Michael S. Hart (deceased 2011), creator of Project Gutenberg, Illinois
  • Dr. Forrest Higgs, Brosis Innovations, Inc., California
  • Rhys Jones, postgraduate, Mechanical Engineering Department, University of Bath
  • James Low, undergraduate, Mechanical Engineering Department, University of Bath
  • Sebastien Bailard, Ontario
  • Simon McAuliffe, New Zealand
  • Vik Olliver, Diamond Age Solutions, Ltd., New Zealand
  • Ed Sells, postgraduate, Mechanical Engineering Department, University of Bath
  • Zach Smith, United States
  • Erik de Bruijn, The Netherlands
  • Josef Průša, Czech Republic

Project sponsors include:[29]


The stated goal of the RepRap project is to produce a pure self-replicating device not 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.[1] From a theoretical viewpoint, the project is attempting to prove the hypothesis that "Rapid prototyping and direct writing technologies are sufficiently versatile to allow them to be used to make a von Neumann Universal Constructor".[30]

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 un-patented products with open specifications. Opening up product design and manufacturing capabilities to the individual should greatly reduce the cycle time for improvements to products and support a far larger diversity of niche products than the factory production run size can support.

Education applications[edit]

RepRap technology has great potential in educational applications.[31][32][33] RepRaps have already been used for an educational mobile robotics platform.[34] Some authors have claimed that RepRaps offer an unprecedented "revolution" in STEM education.[35] The evidence for such claims comes from both the low cost ability for rapid prototyping in the classroom by students, but also the fabrication of low-cost high-quality scientific equipment from open hardware designs forming open-source labs.[4][5]

See also[edit]


  1. ^ a b c Jones, R.; Haufe, P.; Sells, E.; Iravani, P.; Olliver, V.; Palmer, C.; Bowyer, A. (2011). "Reprap-- the replicating rapid prototyper". Robotica 29 (1): 177–191. doi:10.1017/s026357471000069x. 
  2. ^
  3. ^ J. M Pearce, C. Morris Blair, K. J. Laciak, R. Andrews, A. Nosrat and I. Zelenika-Zovko, "3-D Printing of Open Source Appropriate Technologies for Self-Directed Sustainable Development", Journal of Sustainable Development 3(4), pp. 17-29 (2010).
  4. ^ a b Pearce, Joshua M (2012). "Building Research Equipment with Free, Open-Source Hardware". Science 337 (6100): 1303–1304. doi:10.1126/science.1228183. PMID 22984059. 
  5. ^ a b J.M. Pearce, Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs, Elsevier, 2014.
  6. ^ Sells, E., Smith, Z., Bailard, S., Bowyer, A., & Olliver, V. (2009). Reprap: the replicating rapid prototyper: maximizing customizability by breeding the means of production. Handbook of Research in Mass Customization and Personalization.
  7. ^ Wittbrodt, B.T.; Glover, A.G.; Laureto, J.; Anzalone, G.C.; Oppliger, D.; Irwin, J.L.; Pearce, J.M. (2013). "Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers". Mechatronics 23: 713–726. doi:10.1016/j.mechatronics.2013.06.002. 
  8. ^ a b RepRap Family Tree
  9. ^ RepRap Options, RepRap wiki, visited 2.26.2014
  10. ^ Matthew Power (2008-09-23). "Mechanical Generation §". Retrieved 2010-06-04. 
  11. ^ "Gada Prizes". humanity+. Retrieved 25 April 2011. 
  12. ^ "Ingeniøren". Ingeniøren media. 2012-09-26. Retrieved 2012-09-26. 
  13. ^ Chulilla, J. L. (2011). "The Cambrian Explosion of Popular 3D Printing". International Journal of Interactive Multimedia and Artificial Intelligence 1: 4. 
  14. ^
  15. ^ B.M. Tymrak, M. Kreiger, J. M. Pearce "Mechanical properties of components fabricated with open-source 3-D printers under realistic environmental conditions" Materials & Design, 58, pp. 242-246 (2014). doi 10.1016/j.matdes.2014.02.038. open access
  16. ^ Baechler, Christian; DeVuono, Matthew; Pearce, Joshua M. "Distributed Recycling of Waste Polymer into RepRap Feedstock". Rapid Prototyping Journal 19 (2): 118–125. doi:10.1108/13552541311302978. 
  17. ^ Kreiger, M., Anzalone, G. C., Mulder, M. L., Glover, A., & Pearce, J. M. (2013). Distributed Recycling of Post-Consumer Plastic Waste in Rural Areas. MRS Online Proceedings Library, 1492, mrsf12-1492. open access
  18. ^ The importance of the Lyman Extruder, Filamaker, Recyclebot and Filabot to 3D printing – VoxelFab, 2013.
  19. ^ M. Kreiger, G. C. Anzalone, M. L. Mulder, A. Glover and J. M Pearce (2013). Distributed Recycling of Post-Consumer Plastic Waste in Rural Areas. MRS Online Proceedings Library, 1492, mrsf12-1492-g04-06 doi:10.1557/opl.2013.258. open access
  20. ^ Feeley, S. R.; Wijnen, B.; Pearce, J. M. (2014). "Evaluation of Potential Fair Trade Standards for an Ethical 3-D Printing Filament". Journal of Sustainable Development 7 (5): 1–12. doi:10.5539/jsd.v7n5p1. 
  21. ^ M. Kreiger and J.M. Pearce. (2013). Environmental Life Cycle Analysis of Distributed 3-D Printing and Conventional Manufacturing of Polymer Products, ACS Sustainable Chemistry & Engineering1 (12), (2013) pp. 1511–1519. DOI: 10.1021/sc400093k 10.1021/sc400093k Open access
  22. ^ Simon J. Leigh, Robert J. Bradley, Christopher P. Purssell, Duncan R. Billson, David A. Hutchins A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors
  23. ^ RepRap blog 2009 visited 2/26/2014
  24. ^ An Inexpensive Way to Print Out Metal Parts - The New York Times
  25. ^ Gerald C. Anzalone, Chenlong Zhang, Bas Wijnen, Paul G. Sanders and Joshua M. Pearce, "Low-Cost Open-Source 3-D Metal Printing" IEEE Access, 1, pp.803-810, (2013). doi: 10.1109/ACCESS.2013.2293018 open access preprint
  26. ^ Kostakis, V., & Papachristou, M. (2013). Commons-based peer production and digital fabrication: The case of a RepRap-based, Lego-built 3D printing-milling machine. Telematics and Informatics.
  27. ^ "I, replicator". New Scientist. 29 May 2010. 
  28. ^ "The Core Team - who we are",
  29. ^ "Acknowledgements"
  30. ^ "RepRap—the Replication Rapid Prototyper Project, IdMRC" (PDF). Retrieved 2007-02-19. 
  31. ^ Chelsea Schelly,Gerald Anzalone,Bas Wijnen,Joshua M. Pearce, (2015). Open-source 3-D printing Technologies for education: Bringing Additive Manufacturing to the Classroom.Journal of Visual Languages & Computing. 2015; 28226–237. open access
  32. ^ Grujović, N., Radović, M., Kanjevac, V., Borota, J., Grujović, G., & Divac, D. (2011, September). 3D printing technology in education environment. In 34th International Conference on Production Engineering (pp. 29-30).
  33. ^ Mercuri, R., & Meredith, K. (2014, March). An educational venture into 3D Printing. In Integrated STEM Education Conference (ISEC), 2014 IEEE (pp. 1-6). IEEE.
  34. ^ Gonzalez-Gomez, J., Valero-Gomez, A., Prieto-Moreno, A., & Abderrahim, M. (2012). A new open source 3d-printable mobile robotic platform for education. In Advances in autonomous mini robots (pp. 49-62). Springer Berlin Heidelberg.
  35. ^ J. Irwin, J.M. Pearce, D. Opplinger, and G. Anzalone. The RepRap 3-D Printer Revolution in STEM Education,121st ASEE Annual Conference and Exposition, Indianapolis, IN. Paper ID #8696 (2014).


External links[edit]