92 May/June 2018
READER - TO - READER TECHFORUM
>>> QUESTIONS
PS2 Emulation
My Sony CD changer has a PS2
keyboard port to enter the CD title,
details, etc. Instead of typing, is there
a way to emulate a PS2 interface on
a PC or processor board to automate
the key presses?
#5181 Lee
Schaumburg
Proper Motor Selection
I need some tips on selecting
motors for an art project that
continously rotates five different
circular platforms ( 10” diameter, 15
lbs) 360° in one direction, then in
the reverse direction. The complete
rotation of each platform should take
approx 30-40 seconds (not critical).
A direct drive approach would be
preferred (seems simpler), but I could
use a gear reduction scheme if it were
more cost-effective.
#5182 Caitlin Russell
Stony Creek,VA
No Wi-Fi For The Pi
How can a Raspberry Pi be made
to talk to Io T devices over low power
FM rather than Wi-Fi? Looking for
distances under 100 ft.
#5183 Durriyah Shamoon
Eau Claire, WI
New Life For Magnets
Has anyone tried to revive
permanent magnets that have
weakened over time? What is the best
method? Can they be made “good
as new” or is it better to just replace
them?
#5184 Petrina Martinec
Slovenia
Measuring Heat With Crystal
Diodes
I have a bunch of crystal diodes
in my junkbox that I want to use to
measure heat. I seem to remember a
circuit for it some years back that I’m
trying to reconstruct from memory.
It’s not working very well, so I must
be missing something. Anyone have a
simple circuit or explanation of how it
should work?
#5185 John Marion
Bend, OR
>>> ANSWERS
[#1183 - January 2018]
Low-Cost 3D Printers
I’ve been eyeing 3D printers for a
while, and there are now basic units in
the $100 range.
However, it appears that software
can cost between free and several
hundred dollars depending on features
and capabilities. I like free. Is anyone
using free software to create and print
using one of these low-cost printers? If
so, which software and printer are you
using that you would recommend?
Any caveats?
#1 I purchased my first 3D printer
— the Tevo Tarantula — last February,
and I have enjoyed every minute of
it. The Tevo has a large support group
on Facebook (if you’re into that — I’m
not) as well as on Thingiverse. I would
also point you to Thingiverse to find
dang near any model you could ever
want — including a whole multitude
of upgrades for the Tarantula. I myself
have uploaded a few of my own
modifications (my username there is
‘rebeltaz’).
The only drawback to low-cost
printers is that a lot of the controller
boards are not able to properly
handle the current required for a
heated bed. You will want to get
a MOSFET interface board — the
CBD-3D being a popular model — to
offload the current drain to a more
suitable controller.
As for software, you are going
to find diehard recruiters for all the
available packages. Me personally, I
prefer Sketchup for functional models,
since I already had experience with
that program. You will need to add a
plug-in called SolidInspector to ensure
watertight (i.e., solid) models suitable
for 3D printing. Another good free
alternative I use is Blender. This
program seems better suited for more
organic models, although you can use
it for functional designs.
If you lean towards “cloud based”
software (I do not), there are various
alternatives in that category as well —
TinkerCAD being a popular one.
You will also need a slicer
program whose job it is to generate
the g-code understood by the printer
from your 3D model. Simplify3D is
a relatively expensive example, but
both Slic3r and Cura are excellent
freely available alternatives. I
personally prefer Cura due to its more
user-friendly interface.
Finally (well, in closing anyway), I
would also recommend that you think
about getting a Raspberry Pi later
on and load it with OctoPi. This will
allow you to access and control your
printer wirelessly from anywhere on
your local network, or even around
the world if you so desire.
If you ever have any questions
or need any help/advice, I am always
willing to help newcomers to this
wonderful hobby. You can find me on
Thingiverse. Hope to see you there!
Derek Tombrello
Shelby, AL
#2 I'm using Matter Control. By
far, this has been the easiest right
out of the box. In most cases, you
don't need to go into settings, except
to change resolution. When first
installed, you will need to enter the
type and print area of your printer.
The only complaint I have ever had
