reprap-granule-extruder-tudelft1

2
Ṫhe RepRap project
In the beginning of this project, a literature review
was carried out. The goal of this review was to gain
some insight in the RepRap project and to determine
a goal for the project. After the review, the subject of
creating a recycling add-on for the printer was
determined. An extract of the review, with a focus on
the parts about the RepRap project, can be found in
this chapter.
The RepRap 3D printer project is, according to their
creators, “a project to save the world… or at least to
improve it”. The project is initiated by Adrian Bowyer,
member of the Department of Mechanical Engineering
at the University of Bath, United Kingdom 1 . The first
RepRap machine was the Darwin, completed in
October 2008 2 , see figure 2.1. Recently a new
version, the Mendel, was released, having various
improvements like a bigger print area, simpler
assembly and a higher efficiency 3 .
At Delft University of Technology, a Darwin
printer created from a Bits from Bytes kit, is
assembled by a previous project group. Bits from
Bytes is an online reseller, selling complete RepRap
kits made from plexiglass 4 . The available printer is a
RepMan version 3.1.
Building a complete printer costs about $400
when producing all the parts at home, while
commercial kits are available starting from $1200.
2.1
RepRap philosophy
No current engineering manufacturing process is
capable of exponentially expanding production,
because none use self-replication. John von Neumann
was the first person to propose self-replicating
machines back in the 1960s 5 .
The RepRap is built on the idea that anyone
could manufacture products, anywhere in the world.
It is an open-source project, with the goal to enable
relatively low-cost 3d printing. This is realized by
engineering a printer, using mostly simple standard
components and of course the fact that both soft- and
hardware are open-source. The hardware blueprints
are available for free, so parts for the pinter can be
produced at home. This leads to the next
characteristic of the RepRap. Its name stands for
REPlicating RAPid-prototyper: this means that the
machine should be able to print the parts for a new
printer. At this moment the RepRap can fabricate up
to 50% of its own components 2 . To create the first
RepRap of a family one can use a so called RepStrap 6 .
Figure 2.1 - The Darwin RepRap
The RepStrap project has been set-up to help
people build there own RepRap machine without
using an already existing RepRap machine. The goal
of RepStrap is that anyone (no matter what
education) can build his own complete RepRap only
using tool and materials commonly available. Once
someone has built his own RepRap machine, the
printer is able to replicate itself and produce other
useful parts. In this philosophy, the number of
RepRap printer should be able to grow exponentially.
2.2
Working principle
The machine is composed of a frame, built out of
standard thread rods and printed parts. A platform,
where the parts are meant to be built on, can move in
the frame along the vertical axis. A stepper motor
drives this platform up and down by using movement
threads. On top of the frame rests the print head,
which extrudes a thin layer of molten plastic to form a
layer on the base platform. The extruder is moved
along the horizontal axes by two stepper motors and
toothed belts.
6 | Prototyping Lab (IO3028) - RepRap Recycle Add-on