M
and since most laser emitters and LEDs use substantially less, you’ll need to step down the power
using a monolithic voltage regulator. I recommend
the LM317, which can be wired to produce a range of
different voltages.
The design of the emitter casings is quite simple.
I used Neutrik ¼" cast phono plugs, which fit neatly
into ½" copper pipe (Figures I, J, and K). I had ample
space to fit the power regulator circuit (Figure M)
and a tiny laser line generator that I got on eBay.
I used a standard plumbing end-cap to finish the
top of each emitter and then painted them black
(Figure L), and held the copper tube onto the cast
plug using a combination of hot glue and grub
screws.
6. Install and run the control
software.
Controlling the turntable is very easy using either
Milford’s own software or simple serial communication. I have provided a Python library to interface
with these motor controllers, motorcon.py, in the
code section of my website at monkeysailor.co.uk/
code.php.
My “Babylon” version of the SplineScan software
(I used it to scan Babylonian stone tablets) will
support this turntable directly. It’s completely
open source and was released in December 2009
at splinescan.co.uk, so if you’re interested in 3D
scanning then you’re in luck.
SplineScan Babylon uses Python and Pygame,
and has been designed to work on Linux, although
it should work quite happily on Windows machines,
too.
N
A more elegant solution is to draw power from the
motor, using diodes to prevent current feeding back
between the coils (Figure G). The advantage of this
method is that when the controller board powers
down the motor, any lights or laser emitters will
switch off. If the motor is idle but locked, the lights
will be switched on.
So, there you have it: an earnest attempt at a
computer-controlled turntable suitable for open
source 3D scanning, photography, or display.
I mounted mine in an outer casing (Figure N), so
I can scan objects without bouncing laser light all
over the room. In the future, I might even modify
the design to include a moving extrusion head,
and develop a polar 3D printer.
5. Make 2 laser emitters.
If you’re interested in 3D scanning, then you’ll need
to make laser emitters to plug into the ¼" jacks.
Similarly, you could make plug-in LED modules for
illuminating objects on the turntable.
Power taken from the jacks will be around 12V,
Andrew Lewis ( andrew@monkeysailor.co.uk) is a keen artificer and computer scientist with interests in 3D scanning,
computational theory, algorithmics, and electronics. He’s a
relentless tinkerer whose love of science and technology is
second only to his love of all things steampunk.
59 Make:
