The last version of Poor Punctuation had a pretty major flaw - well - two flaws really: (1) It was pretty ineffective in the weapon category; and (2) it wasn't invertible, and flipped over frequently. With those issues in mind, we set about redesigning the antweight, wanting to invest as much Moment of Inertia as possible into it's weapon, which would translate into kinetic energy, and make the 'bot invertible. Here's what we've come up with! Hit Back after viewing an image.
Starting from the bottom-up, we have a 1/16" polycarbonate baseplate, and on top of that is a 6" diameter ring of quart-inch thick UHMW. There are eight #4-40 nuts pressed into the UHMW, which are bolted into from the baseplate.
And the same again with the top plate, and upper UHMW ring. These two pieces leave a gap that is an eighth of an inch.
Because there's no direct attachment of the top and bottom through the walls, we need another way of holding things together, so these are 5/8"-long threaded spacers for #6-32 screws. Between the 13 of them, they ought to keep things fairly solid.
Putting the top aside, you can see here the weapon. The outer ring has 140 20 pitch teeth cut into eighth-inch steel, and two teeth. This piece will be waterjet-cut, and mates with the large gear you see in the bottom-left, which has 35 teeth, for an effective reduction of 4:1. The other two gears are idlers with a bearing in the, spinning freely on the spacer, to prevent the ring from being able to move around. Well ... obviously the ring moves a-round, but not around, if you catch the drift?
The weapon motor is a Turnigy 2204-14T which almost squeezes into the 5/8"-tall space inside the 'bot, but not quite, hence the hole in the top plate. The driving gear for the weapon is press-fit around the can of the outrunner motor. Nifty, eh? The red block is a 10A speed controller for the weapon motor.
Here are all the other bits, including our trusty Sozbots drive speed controllers, although if we have the cash we'll switch them for FingerTech tinyESCs; the drive motors are the same Pololu HP 30:1 gearmotors and 1" wheels from version one, and in fact so are the 1/4" polycarbonate motor mounts. There's a 460mAh 3S lithium polymer battery, and an OrangeRx receiver to wrap the internals up.
Here are all the internals in the 'bot. And there's even a little bit of space! We were contemplating two weapon motors, but we don't have the weight for it. The 'bot is 7" in diameter from tooth to tooth, and 3/4" tall, except the wheels.
At the moment we have about 1.6 ounces unaccounted for, but as you can see in the list above we haven't factored in the weight of all the fasteners yet, nor have we worked out a power switch, so that 10% of the pound will probably be eaten up quickly!
And of course a render in team colours :-) For those counting, in order to get at the battery, we need to undo 17 screws ... that's rather a lot, so we're trying to figure out whether we can make a battery hatch, and keep it under weight ...
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