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Getting parts together |
Building the Chassis |
Installing the Drivetrain |
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Electronics |
Armor |
Weapon |
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Getting the Chassis done and on the wheels was a major milestone, but it's still nothing more than a wheeled dolly without power to the motors. But as I installed the electronics, I realized I needed to do the armor at the same time, so these tasks intermingled.
I had acquired two automotive battery cutoff switches from the local Schuck's Auto Supply, about $15 each. They're clones of the Hella switches many builders use, rated for 10 seconds at 500 amps. In parallel they could handle 1000 amps, and since the theoretical max the batteries could supply was 640 amps, and the theoretical max all the motors could draw at once was 360 amps, I figured they'd be fine. In fact, the reason I chose two was so that I could put them in parallel and eliminate the possibility of a single point failure like the one that took out The Judge in season 3.0. The idea came to me to use the switches in parallel to support power bus bars, and to use a radio Shack project box to cover it all up.
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The project box came with a plastic lid, and an aluminum lid. The aluminum lid was SO soft, that I couldn't really cut it. I tried to cut out the PAM shape from that paper, but it would rather bend than cut. So I took some 18 gauge steel I had laying around and made a replacement lid. |
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The bus bars were cut from the copper meant for the Mechanical Speed Controller (I had twice as much as I needed). This is pretty thick 32 Oz/Square foot copper. The bus bars are about 5" x 3/4. The other piece is the ground plate. |
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Drilling holes to screw the ring terminals to. |
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All the holes drilled. As you can see, the PAM drawing acquired more detail as time went on. The circles show the area that the ring terminals would take up. It was easy to fit 6 terminals between the switches, but I had to double up the 8 input terminals. |
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Next, the box was cut for the wires, and drilled for the nylon stand-offs for the ground plate. |
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The box is test assembled. The plastic lid was cut down to form an insulating barrier between the bus bars and the ground plate. |
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LOTS of wire pigtails. 6" on the power in, 12" on the power out. Long enough to reach everything. |
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The ground plate installed in the bottom of the box. |
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The bus bars installed on the switches. |
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The assembled power distribution box. It was NOT easy to get all the wires fed through those narrow slots cut in the box. There are 8 lines in for 8 batteries, and 6 lines out for 6 EV motors. |
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To mount the switch box in the bot, I fabricated this lexan mounting plate. |
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The vertical supports for the weapon were welded on earlier, and then the angle brackets were welded to them to receive cut-down bolts to anchor the lexan. |
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I needed to make a battery pack for the receiver. I went to Tim's Hobby Shop to get some NiCads to use. Originally I wanted a battery eliminator running off the 24 volt, but that was when I thought I'd need 5 volts for servos too, and I couldn't find anything that would do both with the 1.5 amps the IFI supposedly draws. |
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Hot melt glue serves to hold things together prior to soldering. |
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This pack is center-tapped (the black wire) for running servos, eventually. I didn't need it, but it seemed a good idea to put it in for the future. Another tip, I took a marker and marked where I was going to put the wires to make sure that I wouldn't connect any two cells end to end, making a smoking oroboros out of them. I also used Silver Solder, which is a little stronger and hotter. I don't think I overheated the cells too badly though. It would be nice to have something even better than the 40W iron I used. Note the cells are filled with hot glue now. I figure it'll absorb heat and it's shock cushioning too. |
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A little black MonoCote to shrink wrap it, a label from the P-Touch identifying the wires, and a quick charge from the AstroFlight, and the pack checks out! It'll run the receiver for about an hour |
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The original concept for mounting the receiver. the idea was to have it completely protected by the 1" square tube. Except I wanted the motherboard to be on the other side of those lexan "ears". The mounting holes are too close to the receiver box though to do it that way, and I decided this position would interfere with the return spring. (The top of the bot is to the lower left, by the way.) |
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So, the next best position which will become obvious in later pictures, required that I make this plate out of three layers of lexan, so that the antenna would clear the square tube. In retrospect, this is one of those assumptions that carries along through design that should be re-examined when you make changes. I was concerned about making the antenna protrude because I was going to be all steel. When I went to a lexan top, that should have stopped being a requirement. But you know, even if I hadn't tried to keep the antenna sticking out, mounting an Isaac-16 is a BITCH. |
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I made two plates like this mounting two Victors, and this one, on the receiver side, got the receiver battery mounted on it. (These two pics are actually from 10/24. I made the plates but didn't mount stuff on them until I was finishing the electronics install, but they seemed to go better here.) |
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The White Rodgers contactor got mounted on a plate like the receiver's, but on the other side of the weapon column. It would get the Spike Module and the Solid State Relay on the back. The terminal with the 5 connectors on it was for the ground of the weapon circuit. Two battery grounds in, two motor grounds out, and one ground from the coil. The red wire shorts the motor positive lines to the ground for braking effect. The three barely visible terminals on the far side (the top) are two power in, and a positive to the Solid State Relay, that feeds into the coil, and thence to that fifth ground terminal. The wire clamps are for the power into the victors that will be next to it. |
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