SERVO 05.2014 69
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While the board supports micro
stepping up to 1/16, we will be
using the board set to 1/8. I have
found this setting provides the
smoothest operation. The board
supports a current range of . 8-3. 5
amps per phase, and a voltage range
of 12V-24V. The current price is $52,
but I have seen it fluctuate a few
dollars in either direction.
The power supply used to power
the controller is a 24V 15A switching
supply. It has shortage protection,
overload protection, and over-voltage
protection. It comes with its own
This item will run you about
$28. It will require a three-prong AC
cord (Figure 3).
The stepper motors I selected are NEMA 17 5.5Kg-cm
bipolar motors available from Automation Technology. The
conversion kit is designed to work with this shaft. However,
if you decide to go with a different set, make sure they
have a 5 mm shaft with a flat. The motors are currently
$13 each and you will need three (Figure 4).
These components are used to
connect the stepper motors to your
mill. Before going into any detail on
the recommendedS parts, let's
review a few other conversion
3D Printed Parts
There is a set of printed parts
called the Bubblegum CNC. There
are You Tube videos of these parts,
and a set of parts can be
downloaded from Thingiverse. Just
do a web search on bugglegum
CNC. We will not be using these
parts for the following reasons:
• Requires modifications to the mill.
• Requires very accurate 3D printer.
• Requires bearings and bushings.
• Requires complete mill disassembly of each axis (Figure 5).
• Complicated install; too many components required.
The cost of using this approach will run you nearly
$100 if you calculate the cost of all the hardware and
filament. Note that you still need to purchase the steppers,
controller, power supply, and software.