==== Utterly Offensive Build Report (Robots) ==== **A design that never got built** [[http://media.madoverlord.com/Lg/_B1206/_B120634.jpg|{{http://media.madoverlord.com/Sm/_B1206/_B120634.jpg}}]] In light of the success of the current incarnation of Totally Offensive (success defined as [a] it wins and [b] it doesn't destroy itself in the process), I've decided to build a lightweight, 60lb version of the robot, currently named "Utterly Offensive". The Totally Offensive design seems to be pretty mature; the combination of the strong rear spar and the stiff but springy titanium box section that captures the Magmotor/Weapon gearbox works well and doesn't bend when it delivers its devastating “whack job” attack. The fact that I don't have to build a new frame for T.O. after every event gives me the time and money to devote to the new project (or more precisely, it gives me a way to convince my wife to give me the money to build a new robot). I want to apply the lessons we've learned while building (and re-building, and re-re-building, and re-re-re-building...) T.O. to a heavier bot, while remaining true to the Totally Offensive philosophy of delivering insane amounts of //shock and awe//. At the same time, I want to make improvements wherever I can. There are some clear weak spots in the T.O. design (in particular, the exposed wheels) that should be addressed in a new robot. [[http://media.madoverlord.com/Lg/DSC035/DSC03536.JPG|{{http://media.madoverlord.com/Sm/DSC035/DSC03536.jpg}}]] The first step in the design process was to determine what parts we could re-use in an Utterly Offensive design. As long-time readers know, I'm a big fan of the [[http://www.teamwhyachi.com/TBox.htm|Whyachi T-Box]] drive gearboxes -- and since I have plenty of spares, using them would be an obvious choice. The question is: can 2 T-Boxes, driven by [[smalljohnson.t.html|Small Johnson]] (RS540) motors, push around a 60lb robot? Now, experienced engineers would be able to do the drivetrain and traction computations to figure this out, but because I haven't a clue as to how to do that, I just piled 40lbs of bricks on top of T.O. and tried to drive it. Interestingly, it not only drives very well, but it drives **better** than T.O. does at 30lbs! The extra weight helps the wheels bite in and get good traction, at least on concrete - no wheelspin. So at first glance, it looks like they'll work. It's not like I plan to be pushing the other robots around much! If U.O. does need to push a robot around, it'll just have to bust it into 2 or 3 smaller bits first... [[/pdf/UO-2006.pdf" TARGET="_blank|{{http://media.madoverlord.com/Sm/UO-200/UO-2006.jpg" BORDER=1 WIDTH=96 HEIGHT=124 ALIGN=TOP ALT="Img}}]] With that issue settled, it was time to play around with design and layout (click on the image to see a PDF). This time, instead of wrapping the robot around a S28-150 //shorty// MagMotor, the idea is to kick it up a notch and use its big brother, the [[http://www.robotmarketplace.com/marketplace_magmotors.html|S28-400]]. Furthermore, we will expand the titanium box structure and use it to store the batteries (which were stashed on top in T.O.). Other changes in the design: * Room for up to 6 18v [[http://www.battlepack.com/NIMH%20battlepacks.asp|NiMH BattlePacks]], so we can run at 36v or even conceivably 48v, though I have no idea if the motor can take that kind of stress! * 0.125" Titanium plate (T.O. used 0.100) * Aluminum back spar (T.O. had a Ti one, but it was hard to make). Since U.O's spar does not stick out from the main box, 6061 should be OK. * Outboard wheel bearings to help support the T-Box wheels when the robot does the bouncy-bouncy and comes down hard. These will incorporate an integrated Ti deflector to try and keep debris and enemy weapons away from the wheels. * 12.35lb 5" x 0.5" x 22" blade spinning at 4900rpm if I'm insane enough to run the MagMotor at 48v. Will have ability to add teeth onto the blade tips. May go to a Ti blade with tool-steel teeth. If it turns out I don't need 6 battery packs, I'll be able to add blade weight. Note that 22" is the same size as T.O's blade, so it can be used in an emergency. * Separate weapon and drive [[http://www.teamwhyachi.com/MS1.htm|Whyachi power switches]]. * Signature Self-Righting Hoop, just like T.O. * Since there's no battery box on top of the robot, it can be configured to run inverted with the blade on top (which I refer to as "Buster Mode" in honor of the [[http://homepage.mac.com/hrucker/buster/PhotoAlbum12.html|elegant robot of that name]]). * As configured, 58.6lbs -- way underweight by my standards. Nothing is cast in stone at this point, but I hope to finalize the design after getting some feedback from other builders, and get it running in time for Motorama. I won't be able to compete there, but they might be dumb enough to let me spin it up in their box! More details soon!