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Chapter 3
Experimental Setup and materials
3.1 Fab at Home as a Rapid prototyping test bed
Fab@Home model 1 is a three axis gantry positioning system which is powered by
stepper motors. It mainly consists of:
Chassis
1-Syringe Tool
4-Axis Electronics
Firmware
Application
USB Drivers
Style options
These stepper motors are further attached to lead screws. The tool used for
deposition is syringe based. Right on top of the syringe is a stepper motor which is
responsible for the movement of the plunger and material deposition from the
syringe. The electrical board provides 24 V energy to the four stepper motors. Along
with this are two limit switches for each axis and an optional one limit switch for each
of the axis. A microcontroller is used to control the positioning of the axes and is
connected to the PC with a Universal Serial Bus connection. A graphic user interface
comes with the software and also available on Fab@home‟s homepage establishes
the user connection and allows the control of the machine to manoeuvre and operate
the machine.
The main body, structure and components of the Fab@Home machine are made
from acrylic sheets which have been laser cut as per the dimension desired as per
design. It uses a t-nut style fastening method, high manufacturing tolerances
improves the reliability of the machine. For linear motion of the positioning system,
linear ball bearing blocks of half inch diameter rails are used. The deposition tool
rides on the Y axis which rides on the X axis in a gantry configuration. The z axis
moves the building platform independently to the other 2 axis, this helps in minimum
movement of parts while they are being made. External polymer lead nuts are
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