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Getting parts together |
Building the Chassis |
Installing the Drivetrain |
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Electronics |
Armor |
Weapon |
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After the very graphic demonstration of the physics of Moment of Inertia from the Brake Drum flywheel, I had to redesign. My new idea? A vertical spinner. I have to admit, three of the bots I find most inspiring are Nightmare, Backlash, and Sunshine Lollibot. And learning what I did about moment of inertia, I knew the most effective design is to optimize the ratio of mass at the rim vs. total mass of the disk. In fact, I'd say that my design is halfway between a disk and a drum.
The other thing I learned, after watching Sunshine Lollibot try to twist itself into a pretzel and capsize from gyroscopic precession, was that the design must take that into account. Thus, my wheel will be mounted in a Fork, like a heavy duty bicycle fork. A spring will allow it to twist, and then return to center when the turn stops. With any luck, I'll have the first vertical spinner that can virtually spin in place.
The one worry is the interpretation of a flywheel rule that demands they be mounted rigidly. I have a query out about whether that applies just to the axle, or the relation to the bot. No answer yet. (I suppose that Lolli's frame twisting might have frightened people with the legendary event that would have happened if that twisting had allowed her blade to tear loose from its mountings).
I've also spent a lot of time in ClarisWorks drafting out a full size plan. Here's a very reduced version. The big circle is to indicate the path the tips will sweep out.
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I got lots of goodies recently. Here's a bunch of drivetrain parts from McMaster-Carr. In the front in the cardboard tubes are the axles. Then left to right are shaft collars, Gears, Chain and master links, a box of carbon brushes, 16 bronze bushing pillow blocks, some key stock, and some small timing belt parts for the Mechanical Speed Controller (Which may not be ready in time, so I'm ordering some Victors). This represents about $600. The Victors will be $600 too. |
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As long as we're in spendthrift mode. Here's my IFI system, all set up and running with the aid of a couple of lantern batteries. It draws a LOT of current and won't start up on 8 AA's. If you're keeping count, this is $900 Plus shipping, and the Spike module, and the joystick, more like $960. |
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Ever wonder what $1100 worth of batteries looks like? That's not a typo. $500 worth of chargers there too. If you're a High School kid wanting to be on BattleBots, but you look at all this expense and think you can't afford it, this may not be the level you want to start at. Look at one of the regional competitions with 1, 12, and 30 lb classes. Do well there, and you'll be ready for BattleBots and can expect to win a few matches. Well, I should talk, this is my first bot. But at least I can afford to spend the money. |
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Turning my attention to the axles, I found an easy way to mark it for cutting length. Cut paper to the exact length you want, and then draw across the end with a Sharpie. (The paper here is slid back to show you the mark you get). The marking is consistent from piece to piece. How consistent the actual pieces are depends on you. |
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I just LOVE making curlies! The light shows how it was dancing around before the flash went off. |
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After and Before. I don't know why the turned end appears to be torn out a little, but it's pretty smooth. The edge is filed, and the end is sanded too. Easy to do while it's still in the chuck. |
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Another paper based technique I really like. You saw it on the ill-fated brake flange. I cut the paper so that I could line up the paper with the actual square tubing, and then center punched on the intersection hairlines on the pillow block centers and the centerline of the bar in the drawing. The punches were consistent on all 8 pieces. |
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A light in JUST the right place makes it easy, when viewed from two positions, to see if the drill is perfectly centered. For additional precision, make sure the drill is in contact with the punch hole when you power up the drill. It keeps it from flexing or wobbling. |
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A Good chain breaker is a joy to have. This one's okay, but a LITTLE out of alignment. But it you really Dremel off the ends of the pins, the chain almost breaks itself. Almost. But it is a lot easier than trying to force it out with just the breaker. |
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And a test fitting. Perfect. Not too much tension, not too little. That little chain calculator spreadsheet was right on the money. |
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Those are lightening holes, REALLY. Actually, I had to move the pillow block when I changed the order of the reduction. |
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If you don't trust a drill not to wander, you can turn to the Milling machine to cut holes, a lot more slowly. Here I'm cutting 1/2" holes for the front wheel pod pivots. I am afraid they might be slightly weak though. |
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Andy Miller visits the Workshop, and I take a picture to cheaply exploit his fame! |
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Here, I'm putting "Bullet" disconnects on the BattlePack wires. One tip to avoid putting the wire too far into the female connector is to plug a male connector in first And check your crimps for tightness! I had to redo a couple. The connectors hold fairly well, but in battle they'll be wrapped in tape too. |
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A smallish car battery will run an AstroFlight, but if the current draw is too high, the voltage will drop to the point where the AstroFlight will reset. Not good. Especially if you leave your batteries to charge before a match and come back to find out they didn't. |
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Trying to set up to charge all the Batteries at once got confusing. And plugging one negative into the positive of its own battery would be a disaster! (But I can't use all females on the batteries because then I couldn't chain two packs together for charging, and even worse, I could accidentally put one pack in with the polarity reversed! This way is better). In any case, it seemed wise to label them, and it seemed wise to finally break down and buy a pTouch. The labels are just as hard to peel as the old hard plastic label maker, but they sure do stick better, and look better too. And it was only $30! |
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I LOVE steel. It's SO cheap to pick up remaindered sheet cutoffs. This is 134 pounds, for $0.25 a pound! However, it's pretty heavy for the area. I'm going to have to be careful or I'm going to have an overweight bot. |
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Getting that steel sheared would have put me back at full price, and would have cost hourly labor charges too. Plus there was a day wait on the shear. So, I'm going to have to cut it myself. Here's a cutting guide I whipped up for the angle grinder. Tests so far have not been completely promising. I wish I could justify buying a Plasma cutter, but maybe I can rent one, if I plan all my cuts carefully in advance. |
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