• First place 30 lb class:
Overthruster, Dale’s Homemade
Robots
• Second place 30 lb class: Scimitar,
Blade Robotics
For 2009, the Robot Battles
main tournament is moving to a
larger ballroom to handle the
increasingly large audience. With
Dragon*Con hosting a Robotics
program track specifically to
introduce more people to robots
and robot fighting, the competition
is only going to grow larger and
more intense. So, if you’re tired of
the same old arena, consider
coming to Atlanta over Labor Day
weekend 2009 and checking out
not only the Robot Battles
competition, but Dragon*Con as a
whole. If you are already attending
the Con, and have
(somehow) missed us
for the past 18 years,
then you know what to
do next year. Here’s
some resource links to
get you started:
• www.robotbattles.
com is the event’s
website. Look here for
the rules, photo
galleries, and online
community. Make sure
to join the email list!
• www.dragoncon.org is the
website of the hosting convention,
Dragon*Con, your one-stop shop
for any sort of science fiction,
comics, fantasy, role-playing, anime,
subcultures, and much more.
Überclocker holds Scimitar perilously
close to the stage’s edge.
As a bit of interesting trivia: The
oldest robot fighting competition —
Critter Crunch — began in 1987 at
the MileHiCon in Denver, CO. Robot
Battles is a direct descendant of
Critter Crunch, with almost identical
rule sets. SV
PARTS IS PARTS:
Chain Length Calculat r
and Chain Path Visualizer
● by Kevin Berry
An endless source of information
on bot building is the RFL forum
on Delphi Forums ( www.chief
delphi.com/media/papers/1598).
A recent thread had a great
discussion about a software tool —
Dr. Joe’s Chain Length Calculator,
and the accompanying Chain Path
Visualizer. This handy tool lets a
builder input sprocket and chain
data (up to 12 sprockets!) and out
pops the geometry to build the rig.
The Excel front end drives a macro
called Goal Seek, that does loops of
“what if” analysis to optimize the
design. The outputs and a graphic
visualize the answer, while the raw
outputs are on other tabs.
I haven’t built any chain driven
mechanisms myself that would
require this level of calculations,
but according to the folks on
both forums (RFL/Delphi and
Cheifdelphi), it’s both useful and
accurate.
Dr. Joe Johnson, the creator,
has a few comments worth noting:
2) I move my “idler” up and down
(or left and right) the amount I
plan to build in to my adjuster so
that I can tell if I can actually
tighten the chain.
“This is a tool I use to get my
chain adjuster travels right and to
give my “gut” a chance to “see” the
chain path before I commit to it in
metal. It is not a perfect
tool. It does not have any
way to enter a slider, for
example.
Here is how I use it
most often:
Alternatively, I use it to see if I
can swap sprockets and still tighten
my chain with the different ratio
(this is a non-obvious calculation
at times).” SV
1) I lay out my chain path
(counte-clockwise order
around the chain).
Dr. Joe’s Chain Path Visualizer.
SERVO 11.2008 33