up until a few weeks ago I was spending most of my time on my anti-spam software project SpamButcher - www.spambutcher.com
since the products now shipped - I've gotten back to working on my new bot - "apologies in advance." also - there's plans for an event this january in bellevue - so I've got something to build for..
The quick rundown / recap:
top and bottom are made of .06 lexan, the walls are .03 lexan and the pillars are legos.
drive units are futaba 3002 servos (attached with servo tape, and braced to each other with a piece of carbon fiber)
uses 5 x sanyo 600ma nicd cells (good for about 20 amps peak)
wiring is now all 18ga (I melted the 22ga that I tried perviously)
speed controller for the weapon is a electrifly 30amp (i fried a 10 amp one in testing)
weapon motor is a Promax 370 (like a speed 300 but draws a little less)
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I was initially concerned about run times - I was only getting about 1:30 per charge. but it turned out I was accidently discharging my batteries by leaving them connected to the unplugged charger (cheap ac converter). looks to be good for about 3 minutes with the weapon near full speed. I figure I'm pulling very roughly 10 amps continuous with somewhat more at spin-up.
the current blade is made of aluminum - but I'm intending to replace it with a similarly shaped one, but thinner made out of titanium. I found out the hard way that a scroll saw will definitely -not- cut titanium.
so - basically everything is almost ready to go - except for one major design flaw:
notice that the blade is "slightly" off level? this is what happened after I attacked a coke can (which went flying about 15 feet). the motor shaft is totally bent. surprisingly the bot was still fairly controllable if I kept the blade under 1/2 speed (above that it starts doing a very scary dance). I had similar problems with my last bot - but nothing quite as bad as this. the motor I'm using has a 2mm shaft - which is apparently too thin. possible solutions:
find a motor with a thicker shaft (problem - almost all motors with thicker shafts are much heavier, the ones that aren't are -seriously- expensive)
attach a gearbox with a thicker shaft to the motor (brings up weight and design issues, assumes gearbox will be sturdy enough)
add some sort of padding around the motor shaft to absorb the shock
use a blade that will have some "give" in to absorb the shock
I'm leaning towards the last two options. I may attempt to design a "hybrid" blade - with the main body made of lexan, and the tips made out of titanium.
-Rich
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SpamButcher Combat Robotics