Tangled Marionette Status Report
Part 2:

"Overweight AGAIN?"
My wife at 8:30pm two days before Bash

Well, one of my stated goals for this year was to stay in the weight class I'd designed for. Despite careful planning down to weighing every component and putting it into an Excel spreadsheet, there were just too many things I had left to do and not enough time to do it. So, with only 12 hours before I was supposed to start packing the car to leave for Bash, I realized I was nearly a pound over weight (quite a bit for a 12.9lb bot!), and I wasn't going to have time to do what needed to be done to drop the weight. So, rather than face being outclassed AGAIN with a bot in the wrong weight class, I hurried to finish implementing the plan 'C' that I'd had in the back of my head all along. Perhaps I knew that I wasn't going to make weight...


Despite starting nearly 6months ago, I still somehow managed to not be really FINISHED until checkin-night at Bash. Last minute wiring and other prep took me right to the end. At least this time I got some sleep thursday night, which was good since we were taking the WRX Fraggin' Waggin' this year and my wife can't drive stick. The spikes on the front were originally the forks I made for the business end of the lifting arm. I wanted to try something other than a wedge on a box, so I just drilled and tapped them onto the drive tubes. They worked really well for keeping an opponent in front of me, rather than letting them skirt around the sides too much.
In this rear view you can just barely make out the "biscuit plates" crafted to prevent being stood on end a la "War Machine" at Battlebots Las Vegas 2000. They're the round discs that were left over after I cut the motor holes in the drive pods. This is why I never throw anything away; after 2 minutes on the mill and another minute in the drill press I had two "D" shaped plates that bolted into the back end making it rounded.
The span between the drive pods were skinned with 2-mil Carbon Fiber sheet from Kinetic Composites, Inc.. This is my first time working with composites, and I'm greatful for the tips from Dan Danknick and Jason Bardis on working with it. This stuff is really killer as a high performance to weight ratio product. I'll be spending a lot of time at KCI in the future, because I just can't think of too many reasons to use Aluminum over this stuff when I have the choice. I'd also like to extend a big thanks to Richard Blethen for showing me around KCI's operation and giving me a clue as to what could be accomplished with this stuff.
Another peek at the chain drive system. I used another of my surplus sprockets and a bearing to make an ultra low profile idler sprocket that mounted to the outside face of the tubes. This helped route the chain so that I had better tooth contact on the driven sprockets. To tension the chain, I took advantage of the fact that the Pittman motors have their output shaft off-center from the gearbox. By turning the motor in the concentric mount, I could bring the chains into tension or relieve the tension for servicing.
This worked great except for one thing: With the capacitor clamp motor mounts, I couldn't quite get enough pressure on the motors to keep them from loosening slightly after HEAVY loads. The fight I lost to Jason Bardis' "Hell on Wheels" was probably at least partially due to the fact that I was slipping chain during the last 30 seconds of the fight. The same thing happened in the rumble, but at least in that case I had good chain tension when going in reverse, so I spent the last 45 seconds backing into "Carbon Conflict". I know how to fix this now, if I decide to pursue this design again.
Here's a shot of the fully implemented "Plan C". I removed the Team Delta RCE220's and replaced the Vantec, only this time bolted to the rear bulkhead (which was more protected by the biscuit plates). Where the lifter motor was I installed a third battery in extruded-channel clamps. You can also see the similar clamp I made for the electronics. My receiver and Team Delta RCE85 battery eliminator are housed in the black project box you can see at the bottom. Its nice having a small receiver like the Hitec Micro555 because its much easier to package and protect.
I've been in deep love with these genderless Anderson connectors ever since I got these batteries with them installed. I can easily add/delete/reconfigure battery packs for series or parallel running and for easy charging. My only advice with these is to tape the connectors together, since the "lock" is only mildly mechanical and wouldn't hold if the battery started flopping around inside. My wife got very good at cutting a few short strips of electrical tape just the right length as I pulled the Astroflight 112D off and started bolting the Marionette back up for a fight.
A closer look at the mount for the third battery. I'd originally intended to put velcro straps in to strap the battery into the clamp, but it seemed secure enough on tension alone. After a couple of my last fights this battery had popped loose, so in the future I'll follow through with strapping everything down. Also, off to the right, notice, under the protective electrical tape, that the wires coming into my Vantec come in from the "top", rather than at a 90 degree angle to the unit.
My local surplus place had replacement header blocks that had the funky D-shaped plug that the vantec header uses, except that they turned the wires to a more convenient approach. This allowed me to use the screwdriver from the top and have the wires run directly along the length of the 'bot, rather than having them come in from the top and then having to bend them over and having to adjust the screws with the screwdriver down in the body of the machine. I'm going to see if I can get extras of these and re-sell them as a service to Vantec users everywhere. Oh, they also shorten the height of the Vantec by nearly 1/4" also.
Since the Marionette was basically a large box of Aluminum and Carbon Fiber (neither radio transparent), I was worried about getting decent radio signal to it. Here's my solution, I made a plug from Nylon to fit one of the lightening holes in the drive tube, and bolted it up. A small hole fits one of the "disposable" flexible antenna masts that R/C cars use. I brought a spare, sort of wondering if it would get messed up in a fight, but truth be told the only damage it suffered was from me setting the thing on the table upside down too many times. However, the nearby scratches are from my fight with Jerome Miles' Hyper Active. More on that in the deployment report.

On to Part 3

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