RepRapOneDarwin2

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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

%http://farm1.static.flickr.com/93/244072086_5613d65408_m.jpg%


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:


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*

Darwin Z Stage Construction


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.

Darwin Y Stage Construction

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.

Darwin X Stage Construction

Toolheads

Current Tools

Thermoplast Extruder

This baby is the hot center of the machine. It heats thermoplastic until it melts and forces it out in a thin stream to form a line. Put enough of these lines end to in and you get a layer in a shape. Stack those up and you have an object. We call that additive manufacturing. =)

More information on the Thermoplast Extruder

Future Tools

The plastics extrusion head is only one of many intriguing things one can do with a good cartesian robot and some clever software. You can work with a variety of things such as wax, wood, clay, lasers, markers, a variety of extruders and many other things that haven't even been though up yet! The potential is great, and even better is that development can be done in parallel with the main project.

More information on future ideas for toolheads.


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


Construction Process

Printing in 3D

First Printing - Cheers!

If you've successfully assembled everything and are ready to take the plunge, load up this file into the RepRap build area and start the job. After X minutes a few small cylinders suitable for drinking should appear. Gather your friends and fill them with your age-appropriate celebratory substance of choice. Say a cheesy line, and drink. This will demonstrate some excellent properties of your new machine: that the axes work, your extruder works, and the plastic seal is watertight. Welcome to the Future.

Spare Parts and Replication

Now that you have a working machine, make one each of all the component parts of your machine and put them in a cardboard box on a shelf in a cool dry place. In the future if anything breaks, you'll then have the right spare part. If that happens, replace the part, make another, and put that back in the box. The circle of life.

Also, don't forget to make a machine or two for friends or colleagues. Its by no means required, but it is definitely in the spirit of the project. The project is free (as in speech), but unfortunately real stuff costs money, so the common etiquette is to pay for raw materials / shipping / construction time.

Supply

Infact, since its in the groups best interest, we will probably be doing group buys in the future. The more people we get, the better prices we can negotiate. Additionally, since it is often easiest to buy as an individual, we will also be listing suppliers where you can get parts. This is a good thing since with this shared knowledge, we'll be able to compare prices as an internet community and if someone finds a supplier with the lowest cost with a compatible part, then we can highlight that source and everyone will benefit from the savings. Economics dictates that the larger this project gets, the cheaper its components will be.

-- Main.ZachSmith - 01 Feb 2007