1.
This document provides information on the machines used in the workshop on open‐
source 3D‐printers and milling machines, at the Howest Summerschool
Your job:
Either: prepare your own 3D‐model to be printed, within the constraints described in
the document below
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.
If you prepare a small 3D‐object, you will have the opportunity to print this yourself
during or after the workshop.
Below is a short explanation on how the printers work, so you’ll understand the
limitations of the machines and what kind of 3D‐models can or cannot be printed.
It also provides links to the software. You don’t really need this software, as each
printer will be used with a readily configured computer, but if you want to print from
your own laptop you may want to install this. If parts of this explanation are unclear,
or you’ve got stuck while installing the software, you can contact:
lieven.standaert@timelab.org
Best regards,
Lieven Standaert

2. 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 picture above shows one of the early
models, we will also bring the new Replicators and some Thing‐O‐Matics
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

3.
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’ solid models: they need to have an inside and outside.
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. Let’s ignore this for

4. now.
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. This
is similar to what is used in CNC‐machines, and you could actually ‘type’ your 3D‐
object if you would want to.
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 and tall objects fail often. I would suggest keeping your design less than
3cm tall.
‐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.
‐

5. File description:
Format: STL‐file*
Maximum suggested dimensions: 5x5x3cm high**
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.
Software:
Download en unzip Replicatorg: http://www.replicat.org
Best of luck & see you all next week,
Lieven