RepRapOneDarwin2
Contents
RepRap 1.0 "Darwin"
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
Modeling Software
We have settled on using Art of Illusion (AOI) as our standard modeling software. However, the printer control software takes a standard .stl file to create the slices to make the object, so you can actually use whatever modeling program you want. However, if you intend to modify the files for the objects that make up the printer, you will need to use AOI to edit them.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
-- Main.ZachSmith - 01 Feb 2007
