Tag Archives: 3D printer

Arduino Mega Pololu Shield – RAMPS information & schematic

RepRap Arduino Mega Pololu Shield, or RAMPS for short. It is designed to fit the entire electronics needed for a RepRap in one small package for low cost. RAMPS interfaces an Arduino Mega with the powerful Arduino MEGA platform and has plenty room for expansion. The modular design includes plug in stepper drivers and extruder control electronics on an Arduino MEGA shield for easy service, part replacement, upgrade-ability and expansion. Additionally, a number of Arduino expansion boards can be added to the system as long as the main RAMPS board is kept to the top of the stack.



Version 1.4 uses surface mount capacitors and resistors to further cover edge issue cases. As of version 1.3 in order to fit more stuff RAMPS is no longer designed for easy circuit home etching. If you want to etch your own PCB either get version 1.25 or Generation 7 Electronics. Version 1.25 and earlier are “1.5 layer” designed boards (i.e. it’s double sided board, but one of layers can easily be replaced with wire-jumpers) that is printable on your RepRap with the etch resist pen method, or home fabbed with toner transfer.

This board is mostly based on Adrian’s Pololu_Electronics and work by Tonok. Copper etch resists methods suggested by Vik. Also inspired by Vik’s work with EasyDrivers. Circuit design based mostly on Adrian’s Pololu_Electronics. Joaz at RepRapSource.com supplied initial pin definitions and many design improvements. Much inspiration, suggestions, and ideas from Prusajr, Kliment, Maxbots, Rick, and many others in the RepRap community.

  • Mendel printed RAMPS wired to Mendel.

  • Mendel with RAMPS in enclosure mounted.

  • screen capture of 2-sided RAMPS layout

  • commercially fabbed 2-sided RAMPS wired to Mendel


  • It has provisions for the cartesian robot and extruder.
  • Expandable to control other accessories.
  • 3 mosfets for heater / fan outputs and 3 thermistor circuits.
  • Fused at 5A for additional safety and component protection
  • Heated bed control with additional 11A fuse
  • Fits 5 Pololu stepper driver board
  • Pololu boards are on pin header sockets so they can be replaced easily or removed for use in future designs.
  • I2C and SPI pins left available for future expansion.
  • All the Mosfets are hooked into PWM pins for versatility.
  • Servo style connectors are used to connect to the endstops, motors, and leds. These connectors are gold plated, rated for 3A, very compact, and globally available.
  • USB type B receptacle
  • SD Card add on available — Available now made by Kliment – Sdramps
  • LEDs indicate when heater outputs on
  • Option to connect 2 motors to Z for Prusa Mendel




Safety Tip


Once you start putting electricity into your RepRap – even at just 12 volts – you have to take basic, common sense precautions to avoid fires. Just in case these fail, test your workshopsmoke detector. Don’t have a smoke detector? Get one!


Current schematic shown. For older versions click the image. Click again for full image. This is the schematic of the shield.

Change Log

  • 1.4 August 4, 2011
  1. Changed capacitors and resistors to surface mount components
  2. Added LEDs to mosfet outputs
  3. Added bulk capacitors for each stepper driver
  4. Added pull up resistors to enable to override the Pololu drivers default enabled state
  5. Added mosfet gate resistors
  6. Added pull-ups for I2C
  7. Servo1 connector moved to pin 11 to free 7 for ADK
  8. Fixed thermals
  9. Servo 5V supply is only connected to VCC if a jumper is added
  10. Reset switch changed for small footprint
  11. Moved Aux conectors around a bit and increased board size ~0.1″
  12. Added some space around Q3 for a small heatsink
  • 1.3 May 13, 2011
  1. Added 5th stepper driver socket
  2. Added 3rd thermistor circuit
  3. Added Heated bed circuit w/ 11A PTC fuse, changed to 4 position pluggable input jack to accommodate additional current
  4. Increased board size to 4″x2.32″
  5. Pin order on heater outputs changed
  6. Increased spacing increased to accommodate different connectors
  7. Added connectors for optional 2 motors on Z driver
  8. Added connector for PS control
  9. Improved expansion connector layout
  10. Moved LED towards corner and added resistor to LED circuit
  11. No longer optimised for home etching 🙁
  12. License changed to GPL v3 or newer
  • v1.2 January 04, 2011
  1. Added 0.1″ motor connector to RAMPS for each driver (motors no longer have to be connected on top of stepper drivers)
  2. Added breakouts for serial and I2C
  3. Changed extra power and pin headers around for easier connection to extra boards.
  4. Lost most extra analog breakouts
  5. More silk screen and bottom layer fixing
  • v1.1 September 30, 2010
  1. Replaced power barrel jack with plug-able screw terminal
  2. Added jumpers to select micro-stepping on stepper driver boards
  3. Added debug LED
  4. Changed mosfet pins to be compatible with FiveD firmware
  5. Reduced number of 100uF capacitors to 1
  6. Added 100nF capacitor to 12V input
  7. Put auxiliary 12VIN and GNDIN pads in a straight line
  8. Silk screen and bottom layer cleaned up
  • v1.0 Original RAMPS PCB design
  • v0.1? Point to point wired Arduino MEGA Prototype shield


    • Check List
    1. RAMPS shield firmly seated on Arduino MEGA
    2. No stray wires/metal to cause short
    3. All connections firmly seated, screws tight
    4. Power connection oriented correctly, connected to RAMPS shield (only USB is connected to MEGA)
    5. Thermistor connected to T0
    6. Firmware uploaded
    7. Stepper driver potentiometers to a sane setting (maybe 25% from CCW to start, adjust to enough power to drive axis + not overheat)
    8. Heater wires properly connected
    • Cannot connect?
      • Verify firmware and host software baud rate matches
      • Disconnect USB, reconnect, and retry
      • It may be a problem with the software you’re using (repsnapper). Try using pronterface.
    • Stepper motor getting too hot?
      • Adjust the potentiometer (small screw) on the stepper driver in question by rotating the screw counterclockwise to decrease the current going to the stepper motor.
    • My fan is not working.
      • If you have RAMPs 1.3+ and sprinter firmware (set with the default pins for RAMPs 1.3), try attaching the fan to D9 output.
      • In pronterface, the fan can be turned on by using the M106 command and turned off with M107.

    Stepper Driver Testing

    If you are not sure whether you have a problem with your RAMPS or the stepper drivers you can test that the driver is getting the power and signals it needs to work.

    • Stepper motors getting too hot?
      • Adjust the potentiometer (small screw) on the stepper driver by rotating the screw counterclockwise to decrease the current going to the stepper motor.

    Use a meter of some sort to test the signals at one of the motor drivers. Be careful not to short anything out. You can use a (-) pad in AUX-1 for ground and test the voltage on VMOT, VDD, EN, STEP, and DIR. If all of these are working correctly then the stepper driver is likely bad.

                        High(5V) when disabled, Low when enabled  EN-|     |-VMOT  12V (or voltage at 5A side of input power connector
                                                  Set by Jumper  MS1-|     |-GND 0V                 
                                                  Set by Jumper  MS2-|     |-1A     ---------------| <Motor Coil A   
                                                  Set by Jumper  MS3-|     |-2A     ---------------|____
                                         Not used (tied to SLP)  RST-|     |-1B      -----------------/  |  <Motor Coil B
                                         Not used (tied to RST)  SLP-|     |-2B      -------------------/
                                      Pulse High for each step  STEP-|     |-VDD  5V
    Switches between High and Low when driven direction changes  DIR-|     |-GND 0V



    • What power supply you recommend for your ramps board. I have just finished assembly and looking at the diagrams for a pc power supply and wondering about the separate amperages for the extruder and heated bed. Can they be higher amps without damage?

    Yes, the power supply being capable of more amps than required is the desired configuration. The current shown are the max supported by RAMPS and is the minimum the power supply should be capable of. It is also OK to have both of the inputs on RAMPS connected to one PSU with enough capacity. If you are not using a heated bed the entire thing can run off the 5A side (D8 will just not work).

    • I got a RAMPS V1.3 as part of a kit, but it doesn’t have any installation instructions – just a schematic. Can you point us to a good tutorial for connecting everything? (i.e. stepper motors, opto flag pcb’s, power, data, etc) Some of it (like the single USB port) is obvious, but some of it isn’t.

    See RAMPS1.3 for instructions for version 1.3. There is a version navigation bar at the top of the RAMPS pages that allow you to jump to a specific versions instructions. There is a very helpful graphic under Final Check section.

    • For RAMPS V1.3 the power section of the schematic shows several places with GND/12V (C4/C6, X4-2/1, X4-4/3, VCC/D12). Which one is the GND/12V from the power supply? Is it the round power plug like a laptop power plug? Also, is the outside of that plug GND while the inside is +12V? My kit came with a note warning not to reverse the input power or it would cook the board . . . and a plug adapter with no labels that can be installed either way.

    See the connecting power section of your version’s page. The round plug is on the Arduino MEGA and will only power the MEGA. You need to power the green pluggable connector, it should not be reversible and the board should be marked (+) and (-).

The RepRap Project

The RepRap project is an initiative to develop a 3D printer that can print most of its own components. RepRap (short for replicating rapid prototyper) uses a variant of fused deposition modeling, an additive manufacturing technique. The project calls it Fused Filament Fabrication (FFF) to avoid trademark issues around 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.

To date, the RepRap project has released four 3D printing machines: “Darwin”, released in March 2007, “Mendel”, released in October 2009, “Prusa Mendel” and “Huxley” released in 2010. Developers have named each after famous evolutionary biologists, as “the point of RepRap is replication and evolution”.

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)[1] including scientific equipment.[2] They intend for the RepRap to demonstrate evolution in this process as well as for it to increase in number exponentially.


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

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.[3]
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 toHumanity+.[4]
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.[5]
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. 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.


As an open-source project designed to encourage evolution, many variations exist, and the designer is free to make modifications and substitutions as they see fit. However, RepRap 3D printers generally consist of a thermoplastic extruder mounted on a computer-controlledCartesian XYZ platform. The platform is built from steel rods and studding connected by printed plastic parts. All three axes are driven bystepper 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 uses 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

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).


RepRap has been conceived as a complete replication system rather than simply a piece of hardware. To this end the system includescomputer-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 have 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, Curarepetier 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, or open-source 3D modeling programs like Blender or OpenSCAD.

Replication materials

RepRaps print objects from ABSPolylactic acidNylon(possibly not all extruders capable), HDPE and similar thermopolymers.

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

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.[6]

The RepRap project has not yet identified a suitable support material to complement its printing process.

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.[7]
  • Direct extrusion of solder
  • Conductive wires: can be laid into a part from a spool during the printing process


Other 3D printer designs (such as the commercial Makerbot) and parts constructed by other means (such as Meccano) may be used to “bootstrap” the RepRap process by building RepRap parts. Many such machines are based around 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 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 wiringprinted 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 SargrovePrinted 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.[8]

Project members

The “Core team” of the project[9] includes:

  • Sebastien Bailard, Ontario
  • Dr. Adrian Bowyer, Senior Lecturer, Mechanical Engineering Department, University of Bath
  • Michael S. Hart, 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
  • 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, The Czech Republic

Project sponsors include:[10]


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. 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“.[11]

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 productsfrom 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.

What is RepRap?

RepRap is humanity’s first general-purpose self-replicating manufacturing machine.

RepRap takes the form of a free desktop 3D printer capable of printing plastic objects. Since many parts of RepRap are made from plastic and RepRap prints those parts, RepRap self-replicates by making a kit of itself – a kit that anyone can assemble given time and materials. It also means that – if you’ve got a RepRap – you can print lots of useful stuff, and you can print another RepRap for a friend

RepRap is about making self-replicating machines, and making them freely available for the benefit of everyone. We are using 3D printing to do this, but if you have other technologies that can copy themselves and that can be made freely available to all, then this is the place for you too.

Reprap.org is a community project, which means you are welcome to edit most pages on this site, or better yet, create new pages of your own. Our community portal and New Development pages have more information on how to get involved. Use the links below and on the left to explore the site contents. You’ll find some content translated into other languages.

RepRap was the first of the low-cost 3D printers, and the RepRap Project started the open-source 3D printer revolution. It has become the most widely-used 3D printer among the global members of the Maker Community.


A family using one RepRap to print only 20 domestic products per year (about 0.02% of the products available) can expect to save between $300 and $2000: “…the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average US household already.” Source: B.T. Wittbrodt et al., Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics

RepRap Mendelmax 1.5, 3D Printer with Wade extruder

Extruder Head
Extruder Head

This extruder was designed for the RepRap Mendel (but will work on a Darwin or Huxley with adaptors) and is robust, provides a strong force to extrude, is cheap and DIY. It is an alternative to the standard extruder for RepRap Mendel and has the following advantages:

  • no need to buy/use expensive metal gears;
  • no need to do two precision flats on motor shaft;
  • no need to glue the PTFE barrel;

Other advantages over other extruders are:

  • extrude/print at high speed;
  • good for use with a low torque/cheap Nema 17 motor ; (Needs verification)
  • no need to use expensive and complex tools – just one hand drill, a file and a M3 tap;
  • no need to make splines on motor shaft