RepRapOneDarwin2
Contents
RepRap 1.0 "Darwin"
This page, and those to which it links, are a complete set of instructions for building the first release of the RepRap machine. These instructions, as well as the machine itself are currently under construction. When they are completed, rest assured that we will make a (big) announcement.
Overview
RepRap 1.0 "Darwin" is a rapid prototyping machine that is capable of making the majority of its own component parts. Instructions are available completely free under the GNU General Public Licence from this website to everyone.
As Darwin can copy itself, once you have one you can make others for your friends; or if they have one you can ask them to make one for you. Of course, you can also make as many as you want for yourself; the more you have, the faster you will be able to make other items. RepRap etiquette asks that you use your machine to make the parts for at least two more Darwins for other people, as well as using it to make whatever else you or anyone else on the internet can think up!
Darwin consists of a frame made from rods and printed parts. A flat build platform moves vertically in that frame, driven on screw threads by a stepper motor. At the top of the frame there are two write heads that move horizontally (driven by toothed belts and two more steppers) extruding a thin stream of molten plastic to form a new layer on the build base. The machine prints layer by layer to form a solid object. The build base then moves one increment down, the second layer is extruded, and so on. There are two heads to allow a filler material to be laid down as well as the plastic. This filler is used to support overhanging parts of the objects being built, and is removed when the process is finished.
Images and Screenshots
Video and Animations
Specification
The RepRap 1.0 "Darwin" machine has the following characteristics:
- Working volume: adjustable, but nominally a 300 mm cube
- Working materials: Polycaprolactone and a filler/support
- Configuration: 3-axis Cartesian drive using stepper motors
- Computer interface: RS232 (or USB -> RS232) at 19200 baud
- Two fixed material deposition heads, user exchangeable
- Power supply needed: 8A at 12V DC
- Driving computer and operating system needed: Microsoft Windows, Linux, Unix, or Mac.
Software
These instructions assume that you will be working with the source code of the RepRap software. A little after the first release we will also be putting out binaries for people who do not wish to get into the details of the code.
Installation
Note that all the electronic information needed to build a RepRap machine (that is, the circuit diagrams and mechanical designs, as well as the software for your main computer and the firmware for the RepRap machine's microcontrollers) is available from the RepRap Subversion repository at Sourceforge. In the sections below you will be instructed on how to download all this; not just the software for your main computer.
Follow the link that is appropriate to your computer platform:
- Downloading and installing the RepRap software under Microsoft Windows
- Downloading and installing the RepRap software under Linux or Unix
- Downloading and installing the RepRap software on a Mac
Electronics
The five circuit boards are connected in a token ring, with the communications controller connecting this ring to the computer.
Power + Communications Card
The Power / Comms card is the link between the computer and the RepRap printer. It uses RS232 to communicate over a serial port. If you do not have access to a serial port on your computer, there are widely available USB -> RS232 converters available. It also regulates the input power to 12v and provides power connectors for the other boards to connect to.
Signals are passed round the ring until they arrive at the device to which they are addressed, which then acts upon them. There is an extra single-wire synchronisation link from the X axis controller to the other two axes. This allows all the steppers to move together in any straight line without their needing to transmit data round the ring for each step.
See here for more details on the Power/Comms card.
Stepper Controller Card
The stepper controller card drives a stepper motor. You need 3 of these boards for a fully functioning RepRap. Each board controls the position of one axis. Together, they position the print head anywhere in the 3 dimensional build area.
See here for more details on the Stepper Controller card.
Extruder Controller Card
The extruder controller card drives an extruder (print head). You need 2 of these boards for a fully functioning RepRap. Each board controls one print head. The board controls the temperature and heating coils needed to melt the plastic. It also powers and runs a motor that feeds plastic into the extruder which is then melted and extruded. One board is used to drive a fine nozzle tipped extruder for detail, while the other one controls a course nozzle tipped extruder which is used for bulk infill. Together, these extruders physically do the printing of the plastic.
See here for more details on the Extruder Controller card.
Motion System
Z Stage (Vertical)
The Z Stage (or axis) is the vertical component of the mechanics. It either moves the build platform* up and down (vertically). Unlike the X and Y stages, the Z stage is used less frequently as it is only active between layers or between sections of the build in each layer. However, it needs to support the the build platform*
Y Stage (Horizontal)
The Y stage (or axis) is used in combination with the X stage to move the print head horizontally across the build platform. In Darwin, it is attached to the X stage and the whole Y stage moves along with it as it prints.
X Stage (Horizontal)
The X stage (or axis) is used in combination with the Y stage to move the print head horizontally across the build platform. In Darwin, it is the stage that carries the Y axis and therefore has a heavier load.
Toolheads
Current Tools
Thermo Plastic Extruder
This extruder is the meat of the system.
Future Tools
Milling / Drilling Head
A milling drilling head would bridge the gap between additive manufacturing and subtractive manufacturing. on early and basic versions, it would only really need to support lightweight materials such as wood (MDF) and copper clad boards (PCB milling). These two materials would allow the machine to have the best of both worlds and also the potential to vastly simplify the circuit board creation process.
More information on the Milling / Drilling Head
Support Filler Extruder
The support filler extruder allows parts to be printed with overhangs that would otherwise not be possible to print with just a plastic extruder.
A milling / drilling head would allow RepRap to also make things via subtractive manufacturing. One interesting application would be PCB drilling which would replace the need for having to etch boards by hand. Since the machine is only designed to do additive manufacturing, it would only be able to handle lightweight materials like wood and hopefully copper clad circuit boards.
More information on the Support Filler Extruder
Fields Metal Syringe
Similar to the extruder, a fields metal syringe would be a syringe with a heating element that would be able to melt and extrude Fields Metal, a special metal with a low melting point. This material has a wide variety of uses in making fabricated circuits.
More information on the Fields Metal Syringe
Fab@Home Print Head
The Fab@Home project has created a very nice syringe based print head that can extrude a variety of materials. It would theoretically be very simple to mount it on the RepRap robot frame and then have at it. Currently both projects are blissfully working away in their own separate worlds, but due to the open nature of both projects, collaboration has a very bright future.
More information on the Fab@Home Print Head
Solder Paste Syringe
A solder place syringe would be a very useful addition to the Fields Metal syringe and the PCB Mill head. It would allow the machine to put solder down in places ahead of time to ease soldering of components after the fact. It would even make it much easier to use surface mount parts on RepRapped board.
More information on the Solder Paste Syringe
Pick and Place Tool
More of a pipe dream than a solid idea, but a pick and place head would make RepRap one step closer to hands free circuit board production. Consisting of a simple grabber that would grab and place components in place on the circuit board, the print head could dramatically reduce time and effort required to build a RepRap.
More information on the Pick and Place Tool
Soldering Tool
Also more of a dream than a solid idea, it would be used in conjunction with the solder paste syringe and the pick and place tool, a soldering tool would be able to make the physical solder joint to join the component to the board. It would probably take the form of a heated tip of some sort.
More information on the Soldering Tool
Laser Etch Tool
Consisting of a later and a system of mirrors to redirect the beam, a laser etch tool could be used for a variety of purposes. With a low powered laser, the tool could simply be used to mark designs on a printed object or with a higher powered laser it could even used to do laser sintering to make objects from a high strength metal.
More information on the Laser Etch Tool
Hot Wax Syringe
Nearly identical to the fields metal syringe, a hot was syringe would be used to produce objects with wax. These objects could then further be used in a process called lost wax casing to produce parts out of metal such as aluminum. This would allow the RepRap project to produce its own custom metal parts.
More information on the Hot Wax Syringe
Ceramic Print Head
A ceramics extruder would be extremely useful. It could produce a variety of objects that could then be fired. These objects would have interesting and desirable properties such as hardness, insulation, non-conductivity, etc. For example the extruder barrel could be insulated with a ceramic part printed by a RepRap.
More information on the Ceramic Print Head
Construction
The first thing to do is to get the software you will need working. It will run without a RepRap machine attached, and - as you start to build hardware - you can connect it up in a partly-finished state to your computer for testing.
After installing the software, you should start to build the six circuit boards for the electronics of the RepRap machine. The first (and simplest) controls the communications, the next three control the X, Y, and Z axes of the machine, and the final two control the machine's write heads. Note that it says "start to build". With the exception of the communications board, the boards are all based on the PIC 16F628 microcontroller, and each board will work with just that chip and its power supply. You build the boards with just those components on plus an indicator LED each. Then you connect them all up (first individually, then together) via the communications board to your computer and check that everything is talking to everything else.
Then you put the driver electronics on each of the last five boards to connect to the motors, heaters, and sensors of the RepRap machine. Once more you can test without the rest of the machine - just plug in the stepper motors, for example, and the software will cause them to rotate on your workbench.
Finally, you build the hardware of the write heads and the Cartesian robot that carries them. The order here is not so important, but probably a good way to progress is to make one write head, then make the robot, then get those working together. Finally you add the last head, and your RepRap machine is complete.
Tools
| Stuff You'll Need |
| A computer with a serial port (or USB + serial converter) |
| Power Drill |
| Screw Driver |
| Measuring Device |
| Carpenter's Square |
Consumables
| Quantity | Item |
| 1 | Power Supply |
| 1 | Communications Board |
| 3 | Stepper Controller Boards |
| 2 | Extruder Controller Boards |
| 3 | Stepper Motors |
| 1 | DC Gear Motor |
| 1 | X axis |
| 1 | Y axis |
| 1 | Z axis |
| ? | ground rods |
| ? | timing belts |
| ? | threaded rods |
| ? | limit sensors |
| - | Wires to connect boards |
| - | Reprapped Parts |
| - | misc screws / bolts |
| - | zip ties
|
Process
-- Main.ZachSmith - 01 Feb 2007
