This document provides information about the machines that will be used in an open-source 3D printing and milling workshop. It describes the Makerbot 3D printer and Timelab's miniCNC milling machine, including the file formats and parameters that can be used with each machine. Instructions are provided for installing the necessary software, and examples are given of objects that can be printed or milled.

1.
This document provides information on the machines used in the workshop on open‐
source 3D‐printers and milling machines, at the Howest Summerschool on the 31st of
August.
If you prepare a small 3D‐object and/or a 2D‐profile to be cut, you will have the
opportunity to print/mill this yourself during the workshop. This document outlines
the parameters of the files to be prepared. It also provides links to the software you’ll
need. Installing this ahead of time will allow us to get started faster during the
workshop. Please do so.
If parts of this explanation are unclear, or you’ve got stuck while installing the
software, you can contact: lieven.standaert@timelab.org
PART1: MAKERBOT 3D-PRINTER
Machine:
The makerbot is an open‐source design for a 3D‐printer. This means the build plans
are distributed on‐line and all users can modify or (try to) improve their machines.
Over 5000 of these machines have been built and because of this open‐source design
strategy they are evolving very fast.
The machine creates small objects in plastic (ABS or PLA). This is done by melting the
plastic in a hot print head, then extruding a thin filament of this plastic. The machine
then draws with the plastic and builds the 3D‐object layer by layer.
http://www.makerbot.com

2.
Examples of objects made on the Makerbot
Process:
1‐An STL‐file is imported into the control software, REPLICATORG. .STL is a 3D‐file
format. Most 3D‐software is capable of exporting in this format. Objects need to be
‘watertight’: they need to have an inside and outside.

3.
3D‐model in replicatorG
2‐ When this is done, the 3D‐object is cut into layers. Each layer is a 2D drawing. This
is converted into a description that can be sent to the 3D‐printer.
This is complicated to achieve, but there’s a preconfigured piece of software to do
this for you. It is called SKEINFORGE, and is integrated into ReplicatorG.
Skeinforge has a lot of customizable settings, allowing you to define things like layer
thickness, solidity of your object, print speed and temperature.
As a novice user you can use preconfigured setting, but sooner or later you will need
to dig into this.
GCODE of the object in the previous image
3‐The output of Skeinforge is a text‐file with machine code. This code is called
GCODE, en is in essence a long list of X,Y, Z‐coordinates to be sent to the printer.

4. 4‐In ReplicatorG there is a CONTROL PANEL. This controls the printer directly. You
use it to position the print head and to heat up the printer.
5‐Once this is done, you send the Gcode to the printer, and build the object
Limitations:
‐like most 3D‐printers, this technology is limited to small volumes. Big objects take
long to print.
‐these machines do not print a support material, unlike most commercial machines.
This means you can’t lay down plastic in mid‐air. The little whistle in the image above
is printed on its side, you can’t print it the right way up. Overhangs of more than 45°
are not possible.
File description:
Format: STL‐file*
Maximum dimensions: 5x5x5cm**
Maximum overhang: 45°
Minimum wall thickness for hollow objects:1mm
*Autocad, 3Dsmax, Sketchup and most other 3D‐software can export this.
**de Makerbots can print up to 10x10x12h, but within the context of this workshop
this would take too long.
Alternatively, your object could consist of multiple smaller objects, spread out over a
10x10 build surface.
Preparation:
1‐Download en unzip Replicatorg: http://www.replicat.org
2‐EITHER: prepare your own 3D‐model to be printed, within the constraints
described in ‘File Description’ above.
OR: Go online and take a look on http://www.thingiverse.com You can find a lot of
objects there that can be printed. Choose something that is not too large and that
has actually been printed by more than one person. Save the file and bring it to the
workshop.

5. PART2: timelab’s MINICNC
Machine:
Timelab’s miniCNC is a small milling machine with an open floor. It was designed to
mill small details into large panel or wall surfaces.
The machine has been developed into an open‐source kit and uses the same
electronics as the Makerbots.
http://www.repairablemachines.com
Example of drawing, milled out of 5mm multiplex

6. Process:
The software does not use a 3D‐model, though the machine can do 3D‐objects. For
ease of use, the software uses a black & white or grayscale bitmap. In a Python‐script
the Gcode for the machine is generated from this 2D‐drawing.
The orange lines in the image above are the generated tool paths. These are saved as
Gcode and then opened in ReplicatorG. ReplicatorG controls the machine in the
same way as it does the Makerbots.
Limitations:
‐de Dremel can only be moved straight down. You can mill the top half of a sphere,
but not the bottom half. (though we will focus on 2D for this workshop)
‐the machine can move the Dremel 5cm up‐and‐down. In practice you will be limited
by the length of your milling bit. You can find a 3mm‐wide milling bit that is 5cm long,
but there is no such thing as a 1mm milling bit of 5cm length.
‐when milling a square hole into a surface, the inner corners will bee rounded off by
the radius of the milling bit used.
‐the machine does not have a cooling system on the milling bit. You can try milling
aluminium, but you will have to take care not to overheat the milling bit.

7. File Description:
Format: PNG‐file, 200 dpi, black&white*
Maximum dimensions: 18x18cm
Minimum detail: 1mm **
*Everything in black will be milled away. The black areas of the design should not
touch the borders of the image.
**This is the diameter of the smallest milling bit available
Preparation:
1‐Install the software: an overview of the software to be installed can be found on
http://www.repairablemachines.com/downloads.html
a‐You will need ReplicatorG. This should be installed already if you prepared for the
Makerbot.
b‐You need a driver for the machine. This is an XML‐file that needs to be copied into
the ReplicatorG install‐directory. See website for details.
c‐ You need to be able to run Python. This is a programming language you can
download and install. This is the tricky bit, as you also need to install a number of
libraries. The instructions can be found on the webpage, but differ from platform to
platform. If you are unsuccessful installing these, mail lieven.standaert@timelab.org
for assistance.
d‐ You can test if everything got installed correctly by trying to run the Python‐script
at the bottom of the download‐page. It should run and look similar tot the image
above of the software (the image with the ‘A’ under ‘Process’)
2‐OPTIONAL: Prepare a PNG‐file, within the parameters described above, of a design
you wish to cut out of plate material. Materials like wood, plywood and plexi will be
available at Protospace.
Best of luck & see you all on the 31st,
Lieven