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					        Rapid
      Manufacture


PROFESSOR:          STUDENTS:

Prof. V.Dedoussis      Nicoara Maria-Vasilica

                       Manoiu-Olaru Sorin
                                                 Table of contents

Contents
Introduction.......................................................................................................................................5
Fab@Home Project.............................................................................................................................6
Introduction to the Fab@Home project ...............................................................................................7
   1.1 Goal of this project....................................................................................................................8
   1.2 Basic principal ...........................................................................................................................8
   1.3 Basic components of a fabber (Model 1) .....................................................................................9
      1.3.1 Assembly..........................................................................................................................11
      1.3.2 Electronics........................................................................................................................11
      1.3.3 Deposition material tool ....................................................................................................11
      1.3.4 Software...........................................................................................................................12
   1.4 Steps of building a Model 1 ......................................................................................................13
   1.5 Material types.........................................................................................................................14
   1.6 Functionality principle .............................................................................................................14
   1.7 Performance ...........................................................................................................................15
   1.8 Advantages .............................................................................................................................15
   1.9 Disadvantages.........................................................................................................................15
2 Applications...................................................................................................................................16
   2.1 Flashlight ................................................................................................................................16
   2.2 Frosting as support material.....................................................................................................17
      2.2.1 Silicone bridge ..................................................................................................................17
      2.2.2 Trapezoid ........................................................................................................................18
      2.2.3 Bounce ball/Sphere ...........................................................................................................19
   2.3 Epoxy Propeller .......................................................................................................................20
   2.4 Lego Car Tire ...........................................................................................................................21
   2.5 Cheese House .........................................................................................................................22
   2.6 Chocolate Structures ...............................................................................................................23
   2.7 Silicone Watchband with Embedded Watch ..............................................................................24
   2.8 Box in Cylinder........................................................................................................................25
   2.9 Silicone Squeeze Bulb ..............................................................................................................25
   2.10 Recent developments ............................................................................................................27
3. General impression .......................................................................................................................27
4. Frequent asked question ...............................................................................................................28
   1. How much does a Model 1 cost? ................................................................................................28
   2. How large is a Fab@Home? .......................................................................................................28
   3. What materials can be used with a Model 1? ..............................................................................28
   4. How does a Model 1 compare to a commercial RP machine? .......................................................29
   5. Can I use the Fab@Home product in a commercial environment?................................................29
   6. What could Fab@Home be used for? .........................................................................................29
RepRap Project.................................................................................................................................30
5. Introduction .................................................................................................................................30
   5.1        Goal of this project ............................................................................................................31
   5.2        Basic principal....................................................................................................................31
   5.3        Basic components..............................................................................................................32
      5.3.1         RepRap v1.0 "Darwin".................................................................................................32
      5.3.2         Specifications .............................................................................................................32
   5.4        Electronics.........................................................................................................................33
   5.5        Deposition material tool.....................................................................................................34
      5.5.1 Thermoplast Extruder v1.0 ................................................................................................34
      5.5.2 Paste Extruder v0.1 ...........................................................................................................34
      5.5.3 Future Toolheads .............................................................................................................35
   5.6        Software ...........................................................................................................................35
   5.7       Steps of building.................................................................................................................36
   5.8        Material types ...................................................................................................................37
   5.9        Functionality principle........................................................................................................38
6. Applications..................................................................................................................................39
   6.1 ABS pieces..............................................................................................................................39
   6.2 Water filter .............................................................................................................................40
   6.3 Coat-hook...............................................................................................................................40
   6.4 Corner bracket .......................................................................................................................41
   6.5 The extruder clamp ................................................................................................................41
   6.6 “Swiss cheese” .......................................................................................................................41
   6.7 Brackets- other parts of RepRap machine.................................................................................42
   6.8 Filling in the cracks.................................................................................................................43
   6.9 Silicone enhanced RepRap ......................................................................................................43
   6.10 Stuffs made with RepRap ......................................................................................................44
7. Future plans .................................................................................................................................45
8. Common plans Fab@Home and RepRap.........................................................................................46
9. References ...................................................................................................................................47
                                         Introduction


                                          Early home computers trying to break into home
                                         market. (a) The Honeywell Kitchen Computer cost
                                         $7000 and targeted the cooking as the “killer app;" (b,
                                         c) The general purpose Altair 8800, credited as starting
                                         the home computer revolution, came as a $400 kit.

        In attempt to break the vicious cycle of expensive equipment and niche applications,
there are many lessons to be learned from the rise and growth of an equivalently universal
technology: The computer. The parallels between universal computation technology and
universal manufacturing technologies are astounding. Though the universal computer in its
modern architecture was realized in the 40's, two decades passed before it reached any
significant commercial acceptance. Early inventors themselves could not foresee its huge
potential, famously anticipating a need for as many as five or six machines in the US. The early
commercial mainframes of the 1960s were used mostly for niche applications such as payroll and
military calculations. Like today's rapid prototyping machines, these early mainframes cost tens
and hundreds of thousands of dollars, required hours to complete a single job, had the size of a
large refrigerator and required trained technicians to operate and maintain. Though it was clear to
early manufacturers that the home market offered great potential, it was unclear how to
successfully capture that market. Early attempts of the computer industry to break into the home
market through niche “killer apps" failed miserably: Some brands targeted niche domains such as
Honeywell's “kitchen Computer" geared towards recipes (Figure a). Its high cost and narrow
application prevented it from achieving success. Though several other home computers came
out in the early 1970's, the MITS Altair 8800 (Figure b, c) is generally credited as sparking the
home computer revolution. Designed and sold through Popular Electronics as a $400 kit ($2015
in 2005 dollars), the Alltair 8800 broke the chicken-and-egg cycle: Hobbyists and experts could
now afford to dabble with computers, develop and exchange software and numerous hardware
accessory projects. The availability of computers made it worthwhile to write software, and the
availability of software made it worthwhile to buy computers. Computer history had entered its
exponential growth era.
        Based on this history, it seems reasonable to imagine a low-cost multi- material SFF
(Solid Freeform Fabrication) system in one's home, which could produce objects or even
complete integrated devices from designs which are shared or purchased online. Should such
systems become as available as personal computers or printers are today, the invention and
personalization of small devices could become as ubiquitous as music sharing is today. MIT's
FabLab project provides ample evidence that providing people with automated fabrication tools
serves as an innovation catalyst; ordinary folk, with seemingly no technical background quickly
learn to exploit these tools to design and realize new inventions. The only thing now missing is
the low cost, hackable rapid prototype kit.
Fab@Home Project
Introduction to the Fab@Home project

         Universal manufacturing embodied as today's freeform fabrication systems has - like
universal computers - the potential to transform human society to a degree that few creations
ever have. The ability to directly fabricate functional custom objects could transform the way we
design, make, deliver and consume products. But not less importantly, rapid prototyping
technology has the potential to redefine the designer. By eliminating many of the barriers of
resource and skill that currently prevent ordinary inventors from realizing their own ideas,
fabbers can “democratize innovation". Ubiquitous automated manufacturing can thus open the
door to a new class of independent designers, a marketplace of printable blueprints, and a new
economy of custom products. Just like the Internet and MP3's have freed musical talent from
control of big labels, so can widespread RP (Rapid Prototyping) divorce technological
innovation from the control of big corporations.
         Despite the formidable potential of rapid prototyping technology, its acceptance over the
last two decades has remained disappointingly slow [4]. At present SFF (Solid Freeform
Fabrication) systems remain very expensive and complex, focused on production of mechanical
parts, and used primarily by corporate engineers, designers, and architects for prototyping and
visualization. These factors are linked in a vicious cycle which slows the development of the
technology: Niche applications imply a small demand for machines, while small demand for
machines keeps the machines costly and complex, limiting them to niche applications.
Alternatively, if one could provide either a large market for SFF machines and products or a
simple and cheap SFF machine with which end users could invent products and applications,
then this same feedback coupling could instead drive a rapid expansion in SFF technology and
applications.
         The Fab Lab program is part of the MIT‟s Center for Bits and Atoms (CBA) which
broadly explores how the content of information relates to its physical representation. The Fab
Lab program has strong connections with the technical outreach activities of a number of partner
organizations, around the emerging possibility for ordinary people to not just learn about science
and engineering but actually design machines and make measurements that are relevant to
improving the quality of their lives.
         Fab Labs are the educational outreach component for the Center for Bits and A toms
(CBA) at the Massachusetts Institute of Technology. In 2001 the National Science Foundation in
Washington, D.C. funded MIT's Center for Bits and Atoms, an ambitious interdisciplinary
initiative that is looking beyond the end of the Digital Revolution to ask how a functional
description of a system can be embodied in, and abstracted from, a physical form. CBA's
laboratory research on technologies for personal fabrication is complemented by the field "Fab
Lab" program that brings prototyping capabilities to under-served communities that have been
beyond the reach of conventional technology development and deployment. By making
accessible engineering in space (down to microns, through precision machining) and time (down
to microseconds, through RISC microcontrollers), these facilities have been uncovering what can
be thought of as instrumentation and fabrication divides, and suggesting that they can be
addressed by bringing IT development rather than just IT to the masses. The engineering
capability for design and fabrication at length and time scales described above opens up
numerous possibilities for innovative solutions to common problems. Since local communities
themselves foster this innovation, it can lead to sustainable solutions. High-end technological
solutions have not been addressing problems faced on the local level as yet; therefore, we believe
fab labs will provide a thriving incubator for local micro-businesses.
        CBA Fab Labs have been opened in rural India, northern Norway, Ghana, Boston and
Costa Rica. Fab Lab outreach projects are being explored with a growing group of institutional
partners and countries including Panama, Trinidad, South Africa, the National Academies, the
Indian Department of Science and Technology, and the Africa-America Institute.
        What is a fab lab? Fab Lab is an abbreviation for Fabrication Laboratory. It is a group of
off-the-shelf, industrial-grade fabrication and electronics tools, wrapped in open source software
and programs written by researchers at the Center for Bits and Atoms.


1.1 Goal of this project

        Inspired by this history, the goal of this project is to offer an open-source, low-cost,
personal SFF system kit, which we call “Fab@Home". The aim of this project is to put SFF
technology into the hands of those same curious, inventive, and entrepreneurial citizens. In
addition, through the Wiki web site (www.fabathome.org) we hope to inspire users of
Fab@Home to exchange their ideas for applications and their improvements to the hardware and
software with us and each other. Several machines are already in use.


1.2 Basic principal

        Fabbers (figure 1)- machines that rapidly create useful items on demand from computer-
generated design specification- have been fantasy fodder for decades. And for a good reason: a
machine that could make a huge variety of reasonably complicated objects, and yet was
attainable by ordinary people, would transform human society to a degree that few creations ever
have.
        A fabber enables you to do rapid prototyping safely and inexpensively. Using computer-
aided design or geometric modeling software you design an object – maybe a spare wheel for a
toy truck or an innovative toothbrush- you click print, and your fabber goes to work.
        Instead of using ink or toner the printer uses a variety of gooey substances that harden
when exposed to air. In fact editable things like peanut, butter, chocolate and cheese are popular
with fabber aficionados. Whatever substances you choose the printer methodically builds your
3-D object from ground up, right before your eyes. In addition, fabbers are an open source tool,
which means you have access to their design specifications and can modify them and develop
your own improvements.
                                            Figure 1.Fabber




1.3 Basic components of a fabber (Model 1)


        Forward description will be made regarding fabber Model 1.The Model 1 (Fig.2 and Fig.
3) is the very first Fab@Home fabber design. It includes everything necessary for basic,
multimaterial desktop fabrication. It makes use of a basic "syringe pump" material dispensing
tool, with disposable syringes to enable dispensing of a wide variety of materials. It uses "linear
stepper motors" – stepper motors with lead screws attached - as the actuators, and has 4 axes of
control - 1 for the syringe tool plunger, 1 for the Z axis (the vertical motion of the table on which
parts are built), and 1 each for the X and Y axes to move the syringe tool along the paths
required to build up a part layer by layer. The Model 1 Electronics include a 4-axis amplifier for
the 4 stepper motors, an LPC-H2148 ARM7 microcontroller with USB interface, limit switches
to sense when the X, Y, and Z axes are at the end of their motion ranges, and some (passive)
interface components (a breakout board and cables). The cost of the materials required for the
Model 1 is about US$2300 before shipping, using the current known lowest cost vendors, and
placing all of the orders yourself. It is now possible to order a full kit of parts from a single
source, at a slightly higher price than if you place individual orders yourself.
                                                  Figure 2. Model 1




             Figure 3 : (a) 3D CAD model of an assembled Model 1; (b) An example of assembly instructions



        One concern in developing our design has been that there probably exists a threshold o f
quality required in any new technology kit for hobbyists, below which the excitement of the new
technology will be masked by the malfunctions, maintenance problems, and poor aesthetics.
Users must have a sense of what the technology is capable of before they can grasp how to
modify it and apply it to their own purposes. Our first design has therefore focused more on ease
of use, reliability, and aesthetics than on minimizing cost.
1.3.1 Assembly

        We have tried to assume a modest availability of technica l tools and skills for the end
user, and have tried to facilitate assembly by providing very detailed assembly documentation
(Figure 3(b)). The builder needs to have a laptop or PC with a USB port, and basic assembly
tools including Allen keys, screwdrivers, scissors, pliers, and a soldering iron. Assembly consists
of snapping together the acrylic structure, inserting nuts and screws and threaded inserts, bolting
together the positioning system components and mounting them to the structure, making cables
to connect the microcontroller to the amplifier boards, and the motors to the amplifier boards,
mounting the electronic boards to the chassis, and bundling and routing of cables. Soldering and
crimping of cables and connectors are the most challenging assemb ly tasks, but the project
documentation is exhaustive, offering advice, images and reference websites for these and almost
every other task. The user is expected to have some patience as well: completely assembling a kit
from parts to operation requires roughly 18 hours of labor.

1.3.2 Electronics

        Personal computers today typically provide several USB connections, but no longer have
RS-232 serial ports or parallel ports, though these are still heavily used by robotics and
microcontroller hobbyists. As a result, we have opted to support direct USB connection to our
Fab@Home Model 1 system, despite the additional development work and (internal) complexity
that this entails. We chose to use a microcontroller with an on-chip USB 2.0 peripheral, the
Philips LPC-2148 ARM7TDMI (Royal Philips Electronics N.V.). This is a very high
performance, 60MHz, ash-memory microcontroller with a wealth of peripheral functions for
future expansion, including ADC, DAC, PWM, counter/timers, real- time clock, high-speed
GPIO, UARTs, SPI, and I2C, not to mention the USB2.0 peripheral. In addition, it has 512kB of
ash memory, and 40kB of RAM. The large program memory has enabled us to make a very
easily understood and extensible packet data protocol for communication between the PC
application and the firmware. We use the large RAM space to buffer motion commands so that
real-time motion does not depend on variations in communication bandwidth. With our current
protocol, we can buffer roughly 670 6-dimensional path points (for up to 6 axes of control). The
microcontroller is powered by the USB, and thus can be communicated with even when the
amplifier electronics are not powered. The high computational performance of the device enables
the system to handle receiving and buffering path po ints, sending real-time status and position
data, and controlling step and direction outputs for 6 axes at least 5 kHz.

1.3.3 Deposition material tool

        It was selected a syringe deposition tool for inclusion in the standard Model 1 design
because of the broad range of materials useable with such tools, and for the intuitiveness of
operation. The syringe tool structure (Figure 4(a)) is also constructed of laser cut acrylic parts
with snap fit joinery and T- nut fasteners. A linear stepper motor controls the position of the
syringe piston. We employ a NEMA size 8 frame motor with a rotor mounted lead nut. The lead
screw, which is not captive in the motor, has 3.2 µm travel per full step, and the motor can
achieve a top speed of 5.8 mm/s (1800 step/s), and a ma ximum thrust of 90 N. For the 10cc
syringes we use, this amounts to a 1.1 cc/s maximum volume flow rate, and a maximum syringe
pressure of 460 kPa (67 PSI). The current syringe tool has been designed to allow 10cc
disposable syringe barrels (EFD, Inc.) to snap in and out, and for the piston to be quickly
attached and released from the motor leadscrew for quick changing of materials. A metal nut fits
tightly inside of disposable syringe pistons (EFD, Inc.), and one end of the motor leadscrew has
threading to match the nut. When firmly threaded into the nut, the leadscrew is prevented from
rotating with the motor rotor, and hence the rotor motion is converted to linear motion. Manually
unscrewing the leadscrew from the nut allows exchanging syringes, regardless of how full,
without the need to move or remove the piston. This facilitates the fabrication of multiple-
material objects, and conserves materials. It was also developed a dual syringe tool (Figure 4(b))
which allows two materials to be loaded simultaneo usly and independently deposited. As
mentioned before, tools are bolted to the positioning system, and are modular.




Figure 4: (a) The standard design, single syringe tool, driven by a linear stepper motor;
            (b) A two-syringe version for a life-sciences laboratory.



1.3.4 Software

       The firmware for the LPC-2148 microcontroller was developed in C language, using
Rowley CrossWorks for ARM integrated development environment (IDE) (Rowley Co. UK)
which employs the free GNU GCC C/C++ compiler. CrossWorks is not essential - several
freeware IDE's, such as GNUARM exist which work with GNU GCC compiler. The firmware
performs the following main functions:
       -receiving and parsing of packetized commands from the PC via the USB
       -buffering of motion path segments for fabrication paths
       -immediate execution of jog motion and emergency stop commands
       -configuration of limit switches (present/absent for each axis and direction)
        -communicating axes positions, limit switch states, and other system status to the PC via
        the USB
        -controlling step and direction outputs for up to 6 axes at > 5 kHz step frequency
        The PC application is currently targeted only for the Microsoft Windows (Microsoft,
Inc.) operating system. It is written in C++ using the Microsoft Visual Studio .NET (Microsoft,
Inc.) development environment, OpenGL (SGI Inc.) for graphics rendering, and the Microsoft
Foundation Class library for user interface components. The application has been designed with
the aim of maximizing the intuitiveness of use. The user interface (Figure 5.5) includes a 3D
rendering of a Fab@Home machine which moves synchronously with the real- time position
information sent back by the microcontroller. Dialog boxes allow importing and assigning
material and tool properties to the part geometry, manual jogging of the axes via buttons and
mouse scroll wheel, including the syringe tool motor, as well as a numerical view of the real-
time position and status data from the microcontroller. The application also allows a rudimentary
simulation of the fabrication process - the actual manufacturing plan is executed on a
Fab@Home software emulator, and the motions are displayed in the GUI for quick checking of
towpaths.


1.4 Steps of building a Model 1

       To build and use a Model 1, you will need to do the following:

1. Buy tools required for assembly
2. Choose your style options
5.9. BUILDING A MODEL 1 47
3. Buy the parts for the Model 1
4. Build the cables
5. Build the Machine Base
6. Build the XY-Carriage
7. Build the Z-Carriage
8. Build the 1-Syringe Tool
9. Assemble the Chassis
10. Mounting the 1-Syringe Tool
11. Electronics Assembly
12. Program the LPC-H2148 with the Model 1 Firmware
13. Install the Fab@Home Model 1 Application
14. Commission the Model 1
15. Use the Model 1
1.5 Material types

         This section lists a number of materials that can be used with a Model 1 1-Syring Tool
and similar deposition tools:
- Gypsum
- Plaster
-Playdough
- HotGlue
- Putty
-Uv Coating- you can use it with the syringe tool, and then apply the uv light, or you can spread
it as a layer apply the uv light and then cut the layer to the shape is needed.
- Casting materials such as fast-setting epoxies or rubber. Machinable wax
(e.g.http://www.freemansupply.com)
-ABS plastic in solution. Used on a crafts, you can dissolve
ABS in acetone and use it to patch up defects. With the right amount of dilution, you might be
able to deposit it with a syringe and wait for the acetone to evaporate.
- Silicone
-Rubber Cement
TODO: Low melting point alloys (require heated tool)
-Peanut Butter
-Cookie Dough
- Chocolate
-Caramel


1.6 Functionality principle

        With 3D printing (3DP) technology, originally developed at MIT under the direction of
Emanuel M. Sachs, a powdered material is distributed one thin layer at a time and selectively
hardened and joined together by depositing drops of binder from an inkjet print head. For each
layer, a powder hopper and roller system distributes a thin layer of powder over the top of the
work tray. The inkjet nozzles then apply binder in parallel during a back-and- forth scan of the
entire work area, selectively hardening the part‟s cross section. A piston then lowers the part so
the next layer of powder can be applied. The loose powder that isn‟t hardened remains, acting as
a support for subsequent layers. After the part is built up, the entire tray can be dried in an oven
or fired in a kiln; loose powder is removed with brushes and compressed air. Finished parts can
be impregnated with various materials to make them smoother, stronger, or more flexible.
1.7 Performance

        The accuracy and repeatability depend upon the material you are working with (Does it
flow?Does it change shape with time?), the time you have spent tuning the deposition
parameters, and the nozzle diameter, as well as on the positioning accuracy and repeatability of
the machine. For a “good" material that does not flow, the X-Y (layer plane) resolution is
roughly twice the diameter of the nozzle, and the Z (height) resolution is roughly equal to the
nozzle diameter. In theory, this holds until you approach the positioning resolution of the
machine, which is roughly a ±25 micrometer. The accuracy and repeatability of the positioning
system of the Model 1 have not been measured. At a rough gue ss, without special attention paid
to setup, the repeatability will be roughly ±100 micrometers.
        The build volume of the machine is roughly 8" cubed. The current record for the tallest
object is a bit less than 4", but that was only limited by patience.



1.8 Advantages

-lower price (around 2500 $);
-easy to build;
-not too advance technical preparation to work to the machine;
-small enough to fit on your desktop;
-represent a revolution;
-open source (you can buy it as a kit or you can order your own parts);
-can be customized to your needs;
-uses a long range of materials (including food);
-it‟s safe to use;
-help understanding technology;
-stimulate creativity.



1.9 Disadvantages

-longer time to build (depend upon complexity of the model);
-performance factors are not quite satisfactory;
- cannot use all types of metal (for now!!);
-cannot be use for mass production;
2 Applications
2.1 Flashlight

       An LED flashlight which combines printed silicone, printed conductive silicone, printed
epoxy, and cast epoxy materials, Dan's printable electrical switch and flap-door inventions; an
embedded LED (ultra-bright orange) as the light source; commercial AA batteries which can be
dropped in via the back end; and a rugged, yet handsome and comfortable rubber over epoxy
body. The whole thing was printed in 2 steps: Step 1 (~8 hours) was to print the entire body with
embedded LED, conductive contacts, switch, and endcap, and Step 2 (~30 minutes) was to link
the endcap to the LED by printing and embedding a conductive silicone circuit.




Fig 1. Body of flashlight (100 mm tall ~7h)         Fig 2. Printing the conductive trace (silver-filled silicone) into
                                                    a groove designed into the body




Fig 3 You can see the cast (poured) epoxy in        Fig 4.The embedded trace technique being used
between the inner and outer printed silicone         to connect the thumb switch on the end cap(right)
walls of the body, and the channel                  to the LED anode(embedded in the left hand end)
left for the conductive trace (at left)
Fig 5. A nice view of the LED embedded in printed epoxy       Fig 6.It w orks! Once 2 AA batteries are dropped in via
 in the front end. The flashlight has a very nic e heft and   the end cap; the flashlight can be turned on by pressing
feel -the silicone layers make a nice soft grip over the      (and holding) the switch in the end cap.
solid epoxy body



A movie of the LED flashlight being printed and demonstrated accelerated 300X (total elapsed
time, 8h 8min):
http://fabathome.org/wiki/uploads/1/1b/Flashlight300X.wmv



2.2 Frosting as support material

       Here has been used normal frosting (same as below, albeit a different color) to act as a
support material for various silicone objects. By creating an individual part for each material, we
could have the Fab@Home print the frosting first and then lay the silicone down afterward.


2.2.1 Silicone bridge

       The first attempt at support materials: this is simply a silicone bridge sitting on top of a
block of frosting.




Fig 1. The foundation to our bridge                           Fig 2.A completed bridge on the left
                                                              and a second bridge during construction
Fig 3. Breaking aw ay the frosting (let the silicone harden     Fig 4 Final bridge
overnight).



2.2.2 Trapezoid

        This involves building a silicone shape completely supported by the frosting.This
particular shape could have been printed upside down, but its way cooler to do it this way.




Fig1. First layer of silicone lay out on top of the frosting.     Fig 2. The nearly completed trapezoid. It turned out much
                                                                  prettier than the bridge.




Fig 3 Breaking aw ay the frosting.
                                                                  Fig 4 Final trapezoidal
2.2.3 Bounce ball/Sphere




Figure 1. Start building the mold   Figure 2. Completed mold




Figure 3. Initial silicon layer     Figure 4. Almost done




                                    Figure 6. Not quite a sphere but it looks like



Figure 5. Completed
2.3 Epoxy Propeller

        Here we used the Fab@Home to produce a silicone rubber mold for a 7.5" diameter
propeller suitable for an RC airplane or a rubber-band powered balsa plane. We manually filled
the mold with epoxy while it was being fabbed so that overhanging parts of the mold would not
cave in. The mold did not release cleanly from the epoxy, and the propeller needed some manual
clean up with a Dremel to remove adhering silicone and some rough edges. In the end, the
propeller really works, as can be seen in the video, where we tested it as a “hand powered
helicopter" toy.




                                                              Figure 2. The silicone propeller mold (black GE Silicone II),
Figure 1. The completed mold inside model 1                   completed, and partially filled w ith epoxy




Figure 3.The mold bird-eye-view (~5h)

                                                              Figure 4. The propeller right after removal from the mold
                                                              before manual clean-up.




Figure 5.The propeller after being cleaned up and balanced.




                                                              Figure 6. Mounted on a balsa stick as a toy “helicopter"
A movie of testing out the epoxy propeller as part of a toy
http://fabathome.org/wiki/uploads/2/2d/PropellerMovie.mpg.


2.4 Lego Car Tire




Figure 1. Black silicone replica of a Lego tir e   Figure 2. Close-up of tire show ing treads and spoked interior




                                                   Figure 4. Lego tractor repaired with fabbed tire.
Figure 3. Lego tire mounted on Lego hub and axle
2.5 Cheese House




Figure 1. A house, complete w ith car and driveway, made of
“edible" “spray-cheese", deposited on a saltine cracker




                                                              Figure 2. A second view of the cheese house




Figure 3. A bird's eye view of the cheese house (yummy)
2.6 Chocolate Structures
No comment. DELICIOS




Figure 1. A view of the heated syringe arrangement - just
a thermostatically controlled flexible heater wrapped around   Figure 2
the syringe barrel, then covered with insulation.




                       Figure 3                                Figure 4




                          Figure 5                             Figure 6
Chocolate1.mpg, 2.1MB Movie of Printing a C hocolate Bar:
http://fabathome.org/wiki/uploads/4/47/Chocolate1.mpg
Chocolate2.mpg, 5.2MB Movie of Printing a Chocolate Bar:
http://fabathome.org/wiki/uploads/8/87/Chocolate2.mpg
Chocolate3.mpg, 7.2MB Movie of Printing a Chocolate Bar:
http://fabathome.org/wiki/uploads/b/b0/Chocolate3.mpg
Chocolate4.mpg, 40.6 MB Movie of Printing a Chocolate Bar:
http://fabathome.org/wiki/uploads/1/17/Chocolate4.mpg


2.7 Silicone Watchband with Embedded Watch




Figure 1. Image of CAD design of watch band

                                                      Figure 2. Screenshot of Fab@Home application w ith watch
                                                      band model




                                              Figur
e 3. Close-up of part about 2/3 done




                                                      Figure 4. Finished part on build surface with embedded
                                                      watch




Figure 5. The latest thing in fashion!!
WatchbandDemoMovie.wmv, 28.5MB Movie of watchband fabrication:
http:/fabathome.org/wiki/uploads/5/51/WatchbandDemoMovie.wmv


2.8 Box in Cylinder

        This demonstrates the multiple material capability of the Model 1, and a neat feature of
“fabbing" - it is possible to make one object (in this case a brown box) completely enclosed
inside of another object (in this case a transparent cylinder). This would be very difficult to make
any other way.




Figure 1 A brown silicone box completely enclosed   Figure 2. A second view of the box inside the cylinder
          in a clear silicone cylinder

Similar structure using 2 syringes with different material: New video posted of a Model 1 with a
2-Syringe Tool in action


2.9 Silicone Squeeze Bulb

SqueezeBulbDemoMovie.wmv, 16MB Movie of squeeze bulb fabrication:
http://fabathome.org/wiki/uploads/b/bb/SqueezeBulbDemoMovie.wmv




Figure 1. CAD model of a rubber squeeze bulb                  Figure 2. Screenshot of Fab@Home
Figure 3. Image of squeeze bulb at about layer 60    Figure 4. Image of squeeze bulb at about layer
of 337 layers                                        180 of 337 layers




Figure 5. Side view of squeeze bulb at about layer   Figure 6. Side view of squeeze bulb at about layer
182 of 337 layers                                    250 of 337 layers




Figure 7. Top view of squeeze bulb at about layer    Figure 8. Side view of squeeze bulb at about layer
250 of 337 layers                                    315 of 337 layers
2.10 Recent developments
          Biologists at Rockefeller University have been using a Fab@Home to deposit slime
mold cells in various arrangements to see how the distribution influences t heir ability to form
colony organisms.
         The British magazine Auto Express suggests that fabbers could be used to make auto
parts, allowing individuals to customize cars in ways that were previously available only to those
with large manufacturing facilities.
         While the usual expectation is to make solid objects out of epoxy or other quick-
hardening plastic, the Fab@Home also can be used with plaster, Play-Doh, silicone, wax (to
make forms for casting), low- melting-point metals and a variety of other materials.
         Cornell graduate student Dan Periard and Jennifer Yao '08 have been loading commercial
frosting into the machine to make cake decorations. It's not frivolous work, Lipson says: Because
frosting dissolves in water it can provide temporary support for hollow structures and later be
washed away.
         A high school student in Kentucky is experimenting with a heated syringe to "fab" with
chocolate.
         Future fabbing machines will have to shift from one raw material to another in midstream
and probably deposit material in three dimensions, not just layers, says Lipson. Research in his
lab is taking early steps. Malone has built a machine that uses a rack of interchangeable
cartridges to make devices out of several materials at once. So far, it has made a working battery,
complete with outer case. Malone's long-range goal is to "print" a complete robot, including
limbs, actuators, control circuitry and batteries.
         Meanwhile, Lipson says, just as the Altair inspired tinkerers to add disk drives, keyboards
and monitors and write operating systems and word processors, perhaps the Fab@Home will
inspire new fabbing technology.




3. General impression

         Popular Mechanics has revealed that the video they produced about Fab@Home for the
2007 Breakthrough Award is the magazine's eighth most viewed video of the year and wins a
Popular Mechanics 2007 Breakthrough Award!!! Here is the link for the movie.
http://link.brightcove.com/services/link/bcpid1351322249/bctid1231030451


       Fab@Home has been nominated by The International Academy of Science as one of
Outstanding Technologies of 2007, ranking it among products and innovations produced by
major corporations and defense contractors!

       Automated Creation Technologies has three Fab@Home Model 1 units for sale via eBay!
The auctions will end during the Maker Faire in Austin, TX on Oct 20 & 21, and they will have a
booth with Fab@Home on display.
        The Science Museum, London, UK is including a Fab@Home Model 1 in an exhibit
entitled "Ingenious - centenary of plastics " commencing in May of this year!


         The „fab‟ machine that could spark an industrial revolution:
http://fabathome.org/wiki/uploads/8/81/TheGuardian3-29-2007.pdf

        “By giving everyone the means of production, personal fabrication systems could usher
in a new age of customization “by Hod Lipson

         “I think that within 10 years private individuals will be able to make for themselves
virtually any manufactured product that is today sold by industry. I sometimes wonder if
politicians realize that the entire basis of the human economy is about to undergo the biggest
change since the invention of money.” By Adrian Bowyer, senior lecturer in mechanical
engineering at Bath University.
http://fabathome.org/wiki/uploads/8/81/TheGuardian3-29-2007.pdf



4. Frequent asked question


1. How much does a Model 1 cost?

        Buying all of the parts for a Model 1 currently costs about $2400. Interestingly, the
Altair 8800 minicomputer kit, credited with starting the personal computer revolution,
cost $400 in 1970, or $2015 in 2005 dollars.


2. How large is a Fab@Home?

       The Model 1 stands at 18.5" (47cm) wide, by 16" (40.6cm) deep, by roughly 18"
(45.7cm) tall.

3. What materials can be used with a Model 1?

        The 1-Syringe Tool of a Model 1 is designed to work with almost any kind of liquid or
paste that you can imagine dispensing from a syringe. We have tried using household silicone
rubber caulk, epoxy, cheese, chocolate (with a small heater attached to the syringe tool), cake
frosting, ceramic clay (when mixed with sufficient water), PlayDoh, gypsum plaster. This is
merely a list of the materials we have had time to play with - many, many more materials are
possible, and it is the intent of Fab@Home to make it easy for you to try your own materials. A
good material is soft fluid enough to push through a syringe, but firm enough that it will “stack
up". See the Model 1 User Manual for info on setting up a new material.
4. How does a Model 1 compare to a commercial RP machine?

        Most commercial machines can build larger objects, faster, and with smoother surfaces
and finer details. Several commercial machines also can build with materials such as ABS,
Nylon, and polycarbonate - tough engineering thermoplastics, although parts must be made
entirely of one material, so you cannot have different portions of the same part made of different
materials. Commercial machines are 10 to 100 times as expensive as a Fab@Home, the materials
are proprietary and expensive, and you typically cannot modify the machines, materials, or
software to suit your own needs. The Fab@Home Model 1 allows you to use your own, low-cost
materials, and to build objects that contain multiple materials. The Fab@Home Project is trying
to popularize rapid prototyping/fabbing technology, to make it open source, and to make it
inexpensive, all to get as many people as possible to use and experiment with fabbers. We
believe that fabbing will be a revolutionary technology, possibly as important in the future as
computers are today, and that introducing the public to fabbers in a way which invites
experimentation and improvement is an essential part of realizing this revolutionary potential.
Having said that, the Fab@Home Model 1 is targeted at experimentation and hobby use, and is
probably not ready for the demands of commercial application. Join the Fab@Home project, and
help develop the future Fab@Home models!

5. Can I use the Fab@Home product in a commercial environment?

         Yes. There is no restriction on where or how the Fab@Home can be used. However, be
aware that some of the software is still a little rough around the edges and that the Fab@Home
itself has not been optimized for survivability in a commercial environment.

6. What could Fab@Home be used for?

       Educational purposes, sign- making, architectural modeling, making jewelry molds,
hobbies, and much more.
       RepRap Project
       5. Introduction
        The current movement towards a global economy is generally accepted as a „golden
opportunity‟ for companies to expand their business into a whole new range of markets. This
globalization is however, something of a „double-edged sword‟. New technologies like the
Internet and World Wide Web make it possible for manufacturing companies of any size to
easily expand their target market to include almost anywhere else in the world which has
Internet/WWW capability.
        The increase in competition within the global economy has created new pressures on
manufacturers to meet the challenge of delivering new customized products which will satisfy
increasingly sophisticated consumer demands. The time taken to design, manufacture and deliver
a new product to market becomes in many cases crucial, with any delay increasing the risk of
failure of the business rather than just being a minor setback with the late launch of the product.
        Manufacturing engineers and technologists around the world are familiar with the
„smarter‟ technologies and methodologies which appeared over the last few decades of the
twentieth century as we progressed from Mass Production through other types of manufactures.
Implementation of these types of methods and technologies has generally led to substantial
improvements in manufacturing flexibility, efficiency and shorter times-to-market.
        As part of the transition from the design phase to the production phase, it is generally
necessary to create one or more physical prototypes to allow the demonstration, evaluation and
testing of the proposed product. This creation of prototypes has traditionally been a highly
skilled and time consuming task often accounting for a high proportion of the design phase. The
direct creation of concept models and physical prototypes became possible with the development
of Rapid Prototyping technologies which take the three dimensional electronic CAD models of
the intended product, process the electronic model into a series of electronic cross-sectional
„slices‟ and then use these slices to „instruct‟ a RP machine to build up the model by adding
shaped layers of material to create the finished physical model.
        In the late 1940's eminent mathematician and physicist John von Neumann had become
interested in the question of whether a machine can self-replicate, that is, produce copies of
itself. Von Neumann wished to investigate the logic necessary for replication - he was not
interested, nor did he have the tools, in building a working machine at the bio-chemical or
genetic level.
        The interest to building artificial systems that can create copies of themselves is a
potentially intractable or potentially trivial problem to solve, depending on how you define it and
who you're talking to.
        The RepRap project became widely known after large press coverage in March 2005,
though the idea goes back to a paper on the web written by Adrian Bowyer on 2 February 2004.
        (In April 2005, The RepRap project headed by Dr. Adrian Bowyer of the UK's Bath
University suggested the concept of creating a fabrication device capable of manufacturing the
majority of its components using its own capabilities. By releasing this under the GPL, the
project is on its way to producing such a device. Raw materials should be durable, recyclable,
and relatively plentiful).
    5.1     Goal of this project
         The RepRap machine should be buildable by somebody with no special knowledge or
expertise and it should only require a minimum of tools and those that are needed must be
readily available around the world and be low cost, all construction materials must be common
materials that can be sourced locally in the majority of the world at low cost and the machine
must be able to produce a 100% complete RepRap.
         The goal is, however, to asymptotically approach a 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.
Success on this initiative should open the door to the inclusion of connective wiring, printed
circuit boards and possibly even motors in RepRapped products.

    5.2     Basic principal
         The RepRap is three-axis positioning system with a thermoplastic extruder much like a
motorized glue gun. It makes plastic parts and is made of plastic parts, so it can make copies of
itself. It is the practical a self-copying 3D printer - a self-replicating machine. This 3D printer
builds real, robust, mechanical components up in layers of solid “plastic ink”.
         It is designed to be easy made by itself. So the RepRap team develops and gives away the
designs for a much cheaper machine with the novel capability of being able to self-copy with
about €400 cost expense price material. This is the way that it will be accessible to small
communities in the developing world as well as individuals in the developed world. It could be a
present from a friend who also has one of these machines.
         The RepRap 1.0 "Darwin" machine, the machine about which we are going to talk about,
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 (figure 1) (driven by toothed belts and two more steppers)
extruding a thin stream of molten plastic to form new layers 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.




                                              Figure 1. Paste extruders


       Surprising, this is entirely free of royalty payments because the whole project is
copyrighted and distributed on the web at no cost. You can improve the designs and then use
your original machine to make a better one.
    5.3     Basic components

          5.3.1 RepRap v1.0 "Darwin"

   Cartesian Robot v1.0
   Extruder Controller v1.2
   Opto Endstop v1.0
   PowerComms Boards v1.3
   Stepper Controller v1.2
   Stepper Tester v1.0
   Support Extruder v1.0:
   Termoplast Extruder v1.0
   Tools Kit
   PIC Programmer
                                                                               Figure 2.




                                                                 Figure 3.




          5.3.2 Specifications

The RepRap 1.0 "Darwin" machine has the following characteristics:

-Working volume: adjustable, but nominally 230mm (X) x 230mm (Y) x 100mm (Z)
-Working mate rials: Polycaprolactone and a filler/support
-Configuration: 3-axis Cartesian drive using stepper motors
-Line and space: 0.5mm and about 0.2mm
-Feature size: about 2mm
-Positioning accuracy: 0.1 mm
-Layer thickness: adjustable, but nominally 0.5mm
-Compute r interface: RS232 (or USB -> RS232) at 19200 baud
-Material handling: Two fixed material deposition extruders, user exchangeable
-Powe r supply needed: 8A max, 3A continuous at 12V DC
-Driving compute r and ope rating system needed: Microsoft Windows, Linux, UNIX, or Mac.


    5.4     Electronics

    The electronics are the brains of a
 RepRap system.

     The electronics system is another
 area that is suited for modularity. There
 are basically two interfaces between the
 various systems: the computer/RepRap
 interface and the electronics/machine
 interface. These are generally the same
 regardless of which system of
 electronics you are using.

     The way the RepRap machine talks
 to your computer is over a standard
 serial connection. In the generation 1
 electronics, this is achieved through the
 Power/Comms board with either a real
 serial connection, or a USB->Serial
 converter cable. Either way works the
 same.
                                              Figure 4. Electronic side of the RapRap

     Within the Generation 1 electronics, the boards communicate via a token ring which the host
computer is a part of.
     In the second generation electronics, it works in much the same way. The Arduino is the
entry point for the serial link. A standard arduino uses a USB cable and has the USB->Serial chip
onboard. Some Arduino clones such as the Boarduino omit the chip to save costs and require you
to use a USB->Serial cable as well. The Arduino then internally emulates the token ring network
in order to talk with the host software.
     The RepRap machine itself consists of a variety of electromechanical components. Each of
these has the same interface, regardless of the electronics driving them. Both the generation 1
and 2 electronics have been designed to accept and control the same electromechanical
components. The major difference between the versions of electronics is the microprocessor
controlling them, and the way in which the electronics drive the components. Below, we'll look
at the various parts:

          Electro- mechanical interface
          Stepper Motors
         Opto Endstops
         DC Motors
         Heater
         Temperature Sensors
        The electronics have gradually evolved over time due to this influx of knowledge. They
have tried our best to keep everything compatible, and they believe they've done a good job.

     5.5    Deposition material tool
     The toolheads are the things that actually lay down the build material.
     Currently, there is only one toolhead that is ready for general use, the Thermoplastic
Extruder. However, eventually we would like to support many different toolheads from simple
markers for drawing to support material extruders to paste extruder to lasers for cutting/sintering
to wax deposition heads for doing metal casting. If you have a toolhead that does not heavily
stress the cartesian bot, then it would be well suited for the RepRap platform.

        5.5.1 Thermoplast Extruder v1.0 is the hot center of the machine. It can melt a
variety of plastics and extrude them out in a thin stream to form a line. Put enough of these lines
side-by-side end-to-end and you get a layer in a shape. Stack those up and you have an object.
That's additive manufacturing, and it's the whole principle of RepRap.

         It takes a 3mm diameter filament of a polymer
(usually polycaprolactone); the white rod coming into the
picture from the right), forces it down a heated barrel, and
then extrudes it as a melt out of a fine nozzle. The resulting
thin stream is laid down in layers to form the parts that
RepRap makes.
         People have also tried this extruder with polyiactic
acid and HDPE. Both of these need a temperature at (or
slightly above...) the top end of what this design can handle:
150o C. These should be regarded as experimental at the
moment.



                               Figure 5. Thermoplast Extruder


       5.5.2 Paste Extruder v0.1 is used to extrude a variety of paste-type materials that can
be used as structural support and for other purposes. It is currently under development so its
design will change. But it works and it can be built now.
         The RepRap paste extruder is designed to lay down pastes at room temperature. The typical
consistency of the paste would be the same as icing sugar for cake decoration in a piping bag, or wall-
crack filler such as Polycell Fine Surface Polyfilla, or silicone bath and shower sealant. Indeed all these
and more have been successfully used with this device, though if icing sugar is left in it after use, it
slowly dissolves to form syrup...
        The paste is held inside a balloon (red in the picture) which is,
in turn, held inside an empty fizzy drink bottle (transparent blue). The
bottle is pressurised with air using a bicycle pump, and the pressure
drives the paste out of the balloon, down a tube, and out of the brass
nozzle at the bottom. A section of the tube is made from soft silicone,
which is clamped by a latching solenoid. Closing and releasing the
solenoid controls the flow.
        It might be thought that, as the paste became exhausted, the air
pressure would drop and so the flow would be uneven. But the volume
of the balloon is typically 50 ml and the drink bottle typically 500 ml,
so, by Boyle‟s Law, the pressure drop is only 10% or so - not
sufficient to change the flow rate significantly.
                                                                             Figure 6. Paste Extuder




                                                 Figure 6. Paste Extuder

5.5.3 Future Toolheads

       There are many toolheads left to be developed. We still need lasers, metal deposition
heads, milling heads, and all sorts of other heads taht have yet to be dreamed up.

     5.6     Software

RepRap software requires:

        -A fairly modern computer
        -Decent graphics card (ATI / NVidia) 64MB+
        -Recommended at least 512MB of RAM
        -Serial port or USB <-> Serial converter
        -Ubuntu/Linux preferred, but OSX and Windows also work

        RepRap is a complete replication system, not a simply 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.
    The RepRap team has, for now, identified the free and open-source Art of Illusion (AoI) 3D
modeling system as the front end for the RepRap system. AoI is well-suited for this role both
because of its power to model 3D objects and because it is written in the popular, portable Java
programming language. The basic AoI modeling platform is being tailored to the special needs
of the RepRap project via scripts.

    Work on RepRap's CAM system also being written in Java is currently in an advanced state
of development. That work is being pursued by both Simon McAuliffe and Adrian Bowyer and
is being tested as part of the RepRap 0.1 shakedown exercises.

   The software is free and it can be downloaded from the following website address:
   http://sourceforge.net/project/showfiles.php?group_id=159590 .

   5.7 Steps of building a RepRap v1.0 "Darwin"

Assembly

         It‟s necessary a good bit of bench space, something in the region of 1 m x 2 m should be
fine. At least half a meter square of this space should be flat for setting up frames. Pots to keep
different bits in are a big help. Preparation, assembly and wiring should each take about a day, so
find a stereo and get some biscuits in!
         Obviously you'll need all the parts and components first.
         Start with the Extruder Controller Board, which you should have already made and tested
if you will follow the order on the Assembling Darwin Machinery. You'll need this to test and to
use the finished extruder.
         Next the mechanical parts need to be made.
         Now that the structure has a robot looking all Cartesian, it‟s time to install the electronics
and get it wired .One step is to make the motor drive assembly (Fig.7), then the polymer guide
(Fig.8).

                                                                                                  Figure 7.
                                                                                                  Assembling
                                                                                                  the motor
                                                                                                  drive




                                                                           Figure 8. Assembling the
                                                                           polymer guide
Figure 9. Assembling the extruder

       Another example is the assembling of the Paste Extruder found on the Internet at the
address http://reprap.org/bin/view/Main/SupportExtruder_1_0 .

       Finally assemble the entire machine, test it, and calibrate it.

 5.8 Material types




                                                   Figure 10.


       In this section it‟s about materials that can be used with RepRap and the ways to use
them, as well as the core information needed for their successful application. Many of these
materials will fall under the Polymer class (loosely called plastics).

Polyme rs
        Thermoplastic - polymers that reversibly change phase with temperature. While keeping
within a boundary of temperatures, these phase changes can be done safely and the material
returns to its original solid state after cooling, without any alteration in its original properties.
        These are the various suppliers that are used from the category of polymers:
     Polymorph(Polycaprolactone)
     HDPE(High Density PlyEthylene)
     ABS(Acrylonitrile Butaniene Styrene)
     PLA(Polylactic Acid)
     PP(Polypropylene)
        Duroplastics - plastics that once hardened cannot reversibly change phase (molten)
through heat. Solvents may dilute some of them (Acrylics, Polyesters in their lower molecular
weight form) and by evaporation of the solvent they will harden again. This application, very
common in solvent based varnishes and paints, is nevertheless not practical for RepRap, as the
volatile solvents take a long time to evaporate and in large section or layer thickness, this
evaporation cannot be regulated and controlled so as to produce uniform deposition layers
(bubbles, hardening imperfections).
        For rapid prototype deposition, Duroplastic resins have to fulfill some conditions like:
long work time, correct viscosity and plasticity, after deposition to have adhesive properties and
after that there has to exist a mechanism by which the polymer will set and harden.

Types of duroplastics:
    Spontaneous polymerization resin Blends
    Triggered polymerization resin blends
    Other Additives, Monomers, Fillers

Catalysts and Initiators

Catalysts for dual-component mixes-spontaneously catalyzed systems, they start the
polymerization reaction as soon as the catalyst comes in contact with the monomer. They do not
need any further external input to fulfill their initiator role, be it heat, mo isture, radiation (UV,
visible, IR...).
Catalysts for single-component mixes –triggered catalysts, they need a triggering effect to start
their initiator role.

Ceramic slurries - to create very hard and strong ceramic structure. Silicon nitride is currently
being contemplated in this role, though several similar refractories are being considered.

Electroconductive materials

Wood‟s or Field‟s metal- low- melting point metal alloys (lower than the melting point of the
plastic) to incorporate electrical circuits into the part as it is being formed.
Silver- filled polymers - are commonly used for repairs to circuit boards and are being
contemplated for use for electrically conductive traces.

Chocolate has been proposed as a whimsical extruded material. This could allow the
manufacture of complex 3D Easter eggs and other such items.


 5.9 Functionality principle
        Regarding mechanical functionality the Z axis of the machine is the vertical component.
It moves the bed up and down. Unlike the X and Y axes, the Z axis is used less frequently as it is
only active when a layer is finished (it moves the bed down a notch). Thus it can move more
slowly that the X and Y axes, and is driven via 4 screw threads synchronized by a timing belt.
This gives slow speed but increased precision.
        The Y axis is used in combination with the X axis to move the print head horizontally
over the bed. Because they are in constant use they need to move quickly and are therefore belt
driven.
        Once set up, these axes find their home positions using opto-switches. From the home
positions the axes can achieve repeatable movements to within 0.1 mm.
        The Cartesian robot is mechanical element of Darwin. The assembly moves the tool
heads around in the X & Y planes to print each layer shape and drops the Z axis down one
increment when each layer is completed.



6. Applications

        This section shows some example objects made by RepRAp machines. A lot of these are
steps on the road to having the machine copy itself rather than more instantly-appealing utility
items like coat hooks, mobile phone cases, car headlamp housings and so on. As any biologist
will appreciate, having the machine copy itself is the most useful possible thing we can make it
does, and is the primary goal of the whole project.

6.1 ABS pieces




                                                                    Figure 11.



        Acrylonitrile butadiene styrene (ABS) works really well in the RepRap extruder. Its
melting point is 105°C which is less than HDPE so it does not stress the extruder as much
thermally. It is harder than HDPE and PCL so it is quite tricky to get e nough motor torque
without the clutch slipping. Loosening the top springs on the pump and tightening only the
bottom springs helps as well as lubricating the filament with oil.
        Its warping is a lot less than HDPE and a bit more than PCL, but the main advantages are
that the die swell is low and the filament is very compliant. It follows the head movement
accurately even when extruding 0.5mm filament at 16mm/s. That gives objects good definition
and sharp corners.
        It is also much harder than the other two plastics and makes very rigid objects.
   6.2 Water filter

         This is a water filter insert made in
RepRap. Actually, it's a bit of a cheat: the model
for it is a simple disc. But he has enhanced the
host code so that you can plot multiple outlines of
an object one inside another. Add that to the fact
that you can set the infill width to whatever you                                                 Figure 12. Printing
like and the part becomes trivial to make. It was                                                 the water filter
done in a home RepRap and it took about 20
minutes to be built.




                                                                          Figure 13. The water filter
                                                                          incorporated into the pipe


           It was tested to filter some non-potable water as input. The output water was cleaner, the
   dirt remaining on the filter, but still non-potable.

   6.3 Coat-hook
         It took 12 minutes to be designed in Art of Illusion, and then
 it was set running in a home RepRap machine. The quality is a bit
 splodgy because the machine that built this piece had a maximized
 build speed, the outline printing rate was overcooked a bit.
         There are two objects in the Art of Illusion model: one has
 through-holes for screws; the other just has indentations to allow
 you to drill your own subsequent to manufacture. In the latter case
 you can put the holes in different places if you need, of course.
 Then again, you can just move the holes in the AoI design.




                                   Figure14 . The design
                                   for the hook                                     Figure 15. Building
                                                                                    the hook
 6.4 Corner bracket

         It looks like we have a failure mode for PLA
corner brackets. This picture shows a relatively recent
bracket torn apart by the forces of fitting an 8mm rod
into it and over-tightening one of the grub screws.
         As you can see, the break is hardly a neat
delamination, and the line of separation is at the apex of
a teardrop-shaped hole. The corners also have little
plastic in them, even after being squared off so they
parted easily too.
                                                   Figure 16


 6.5 The extruder clamp

                If the extruder clamp is missing
       from the pile of parts in the "complete"
       RepRap, you can remediate it. It would take
       about 12 hours to print in PLA. As you can
       see, the clamp grabs a 16mm PTFE rod very
       well even without the clamping screws.
       There is also a channel in the clamp to take
       a 4mm self- tapping screw with which I
       intend to further secure the PTFE.
                There are a few diagonal bracing
       brackets, but those are no problem and
       shouldn't take more than a couple of days to
       run off.
                                                                     Figure 17
 6.6 “Swiss cheese”


             RepRap made a Darwin corner bracket in 50%
     filled ABS. It took 2 hours 35 minutes. It feels pretty
     sturdy but there is some delamination through the thin
     section of the corner facing the camera. It‟s a bit of a
     weak spot in the design. Also the base is a bit warped
     as it was not used a raft.


                                                         Figure 18
                                           Figure 19. “Swiss cheese” made with
                                           PLA(close- up shot of that corner bracket)

6.7 Brackets- other parts of RepRap machine




                                                       Figure 20. X-axis PCB
                                                       holder



        It works really well. Above is the X-axis PCB
holder. Even with PCL this has a slight tendency to
curl up at the ends because it's so long and thin. But
with balsa wood, no such problem - it builds perfectly.
It works especially well if you run the first layer a little
low. This causes the extruder to force the polymer into
the grain a bit, giving good adhesion. But the balsa is
so weak that it's still easy to separate the built part
(though some bits of balsa come away with the part,
they are simple to clean off with your fingernail).
         It was made a little aluminium template to cut
the balsa round with a scalpel and to act as a jig for the
holes through which was bolt it to the base. And, as it
                                                                Figure 21. General PCB
gets a bit tatty, you can double its life by turning it
                                                                brackets built in one build
over, of course.
   6.8 Filling in the cracks

              Here is the extruder working with Polyfilla wall-crack
     filler paste. As with the silicone yesterday, the flow rate is still
     a little high (next: try a smaller diameter nozzle), but it works
     smoothly.
             The principle of the device is proved. Now what needs
     to be done is to improve the design: it's a bit difficult to refill,
     and that needs to be made better. Also, at its heart, is a turned
     brass part that I think can be replaced by a rapid prototyped
     one. The nozzle is a slightly modified version of the one on the
     polymer extruder, but there is no reason for the two not to be
     identical.
                                                             Figure 22


   6.9 Silicone enhanced RepRap
        Here is the paste extruder working on RepRap. It consists of
a 500 ml fizzy drink bottle containing a balloon that in turn contains
the paste. You pressurize the bottle using a bicycle pump, and the
flow is controlled by a latching solenoid that clamps onto a soft
silicone tube on the way to the nozzle. The clamp is the red
rectangular piece hovering over the tube in the picture below (the
solenoid is behind the green support). When the red bit moves
backwards the flow is shut off.
        Here is a close-up of it laying down a test square. The
material is PolyDiMethylSiloxane (PDMS - silicone bathroom
sealant). I had the flow set too high and the movement speed too
slow, so it's flooding a bit. But that should be easy to fix.
The controller electronics are really simple - just the standard
RepRap       controller    with     slightly    modified     firmware.
       The silicone doesn't set if you leave it in the device
overnight, except for the bit actually in the silicone tube that forms      Figure 23. Paste Extruder working
the valve. This is caused by the fact that the materials are the same,
and so a little of the catalyst that caused the tube to polymerise          3
when it was originally made is leeching out and setting the working
material as well. To fix this we just need a soft tube of another
material.
       When the valve closes, it deposits a splodge of goo as it
displaces some material. The tube was used for the valve is 3mm
internal diameter, which it doesn't need to be. It will be better to
find some of 1mm I.D. That should cut down the closure volume,
and          hence          the         problem,         dramatically.
       This means that we should be able to work with just about
any material that is a paste at room temperature.
                                                                                     Figure 24
6.10 Stuffs made with RepRap




            Figure 25. A wheel                        Figure 26. A glass




    Figure 27. RepRAp Logo                 Figure 28. A colored glass




 Figure 29. Flask with overhangs in PLA   Figure 30. PLA Filament works (The
                                          material has some artistic
                                          possibilities)
 Figure 31. Bed Corner Printout



7. Future plans
        The next version of RepRap will be RepRap 2.0 “Model”. It‟s hoped to be able to
incorporate more advanced features to bring an improved machine. This area is 'mostly' pure
speculation. There is however a tinge of reality in the claims presented here. Feel free to attempt
to do any of these things and report back.
        The "Mendel" design is expected to offer several improvements over the “Darwin”
design. A provisional list of improvements (gleaned from conversations in e-mail between
participants) is:
                                      Use of PLA as main plastic feedstock.
                                      Metal deposition head.
                                      Capable of manufacturing own electronics.
                                      Automated exchangeable head mechanism.
                                      USB Interface.
                                      DC Servos instead of stepper motors.

        A fundamental principle of the RepRap project is that anyone who has a RepRap machine
will always be able to use it to build the next generation improvement. That way even if you start
with the very bootstrap machine, you can always build your way back up to the full technology.
Of course this may not always be possible, but we will try our very best!

        The names will always commemorate famous biologists - after all, the point of RepRap is
replication and evolution.

PrintingMaterials
        Thermoplastic is the only material we use at this point in time. It is very versatile
however. Combine that with some clever geometry and some solid engineering skills and you
have quite an amazing capability in computer controlled manufacturing.
FillerMaterials
        Bulk filler materials would be powders added to thermoplastic to increase its stiffness,
toughness, or wear resistance.
Common filler materials used with thermoplastics include glass fiber and talc:

CementMaterials
CeramicMaterials
Colourful Materials
ConductiveMaterials
ConductiveMaterials
Edible Materials
FlexibleMaterials
PreciousMetals
PreciousMetalClay
RefractoryMaterials
CeramicShell
WaterSolubleMaterials

Future Toolhads

       There are many toolheads left to be developed. We still need lasers, metal deposition
heads, milling heads, and all sorts of other heads taht have yet to be dreamed up.

http://reprap.org/bin/view/Main/ManagingYourFilament


8. Common plans Fab@Home and RepRap

Fab@Home and RepRap Multiple Material File Format



       We are getting together with the Fab@Home team to try and establish a common
standard for multiple material data exchange.

        To print objects using multiple materials we need also to represent objects made by more
than one material. This page sets out and discusses the file- format definitions for that. Our
preliminary approach is to create a hybrid file that contains one STL for each material type.
There is also a legend in the file that tells which STL is which material, and where it is
positioned.


Better than STL



       Well, almost any format really, STL is the worst data structure ever devised. However,
what they (AB) would like to do next is to have a format that goes:
       The file type extension is: .csg
       The mime type should be: model/re prap-fab-at-home-item

        Which would be a CSG tree with planar half-spaces as leaves. It is easy to convert
(correct) STL files to this format using Tony Woo's alternating sum-of-volumes algorithm.

CSG has a number of advantages:

      Always solid - the item may not be the right shape if you make a mistake, but it never has
       open faces, missing edges and so on.
      Fast to evaluate for 3D printing - CSG lets you know very fast if any given point in space
       is inside or outside.
      Easy offsetting - to offset a CSG object made from planar faces, you just change the
       constant term in the face equations; everything then sorts itself out automatically.
      Easy to slice - you just set the Z terms in the CSG expression to the height you want, and
       you get a slice immediately.
      Easy to infill - you cast rays across for the infill zig- zag; you membership test the middle
       of each ray segment and never get a dud one.
      Potential function - at any given point in the object, you know which surface generated
       the potential at that point. That allows you easily to do things like specifying variable
       material properties through a solid so (for example) it's rigid polymer at one end
       gradually becoming bendy as you approach the other.




9. References

www.reprap.org

http://blog.reprap.org

www.wikipedia.com

				
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