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Getting parts together |
Building the Chassis |
Installing the Drivetrain |
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Electronics |
Armor |
Weapon |
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I can't really call it Progress. But over time, watching Battlebots, I got addicted, as many do, and decided to build. I've gone through many ideas, some of which I may yet do, once I have more tools (any excuse to buy more tools) but I did come up with a design that I could do with the things I have already. Being laid off by Palm, with a generous severance, and having sold a house, I decided there was no time like the present to take the summer off (and then some) and actually DO something. The actual design? Well, since I've already mentioned it on the Forum - the intent is a mainly rectangular bot with three flywheel driven hammers (probably trailer brake systems) and a mechanical speed controller of my own design. I'm going to call it "Strike Anywhere" and paint it to look like a box of kitchen matches (cute, eh? "Close BattleBox Before Striking"). I've also asked my friend Dean Norton to do up a team logo, which should be really cool.
This is the place where people go from talking big ideas to actually doing something about it. Where the plastic meets the box floor. I.E. when you finally spend some money to implement your ideas.
Like many builders, my first stop was a trip to MECI to buy electric motors. The big black ones are the ever-popular EV-Warrior motors. The ones in the middle are listed as high speed motors, I was planning on using them to spin the hammer flywheels but they look kinda small, but supposedly they'll do 18,000 rpm at 12 volts. The smallest ones are going to drive my mechanical speed controllers. Planning for back-up, I have two extra EV's, and one extra of the others. Actually, I have one extra of each kind of EV, because they come with a slight bias for either clockwise or counterclockwise rotation. Word has it that MECI has run out of counterclockwise, and considering when these puppies shipped, you may be looking at the last of them.
I also lucked out, I think, in that they also shipped the power wires for the EV's. They don't always come with the motors.
As for other materials, for testing purposes, I'll be pulling the 4 channel Futaba from my long-disused glider, but eventually I'll be replacing it with a PCM radio. I've also got a good supply of angle and flat steel, and a little square tubing. Everett Pipe and Steel is close by, so I can get what I need any time. Monday I plan to chase down some sprockets and the wheels I've had my eyes on, and look into the weapon parts.
Two answer a question about EV timing. Here's a CW and a CCW open at the same time. Notice the mirror symmetry, and how the edge of the magnet lines up with the connector hole. Someone smart could calculate how many degrees one would need to rotate the brush assembly to achieve neutral timing.... I could double check, but I'm pretty sure the polarity of the brush assemblies is identical.
I spent the week running from place to place. The RV dealership next to where I was getting my car worked on suggested a place called "Six Robblees" for trailer brakes. Where I picked up the trailer brake assembly below. I felt kinda bad, the guy kept fetching things one part at a time until I had everything I needed. First the brake, then the drum, then the spindle and bearings. This picture was taken after I'd taken the studs out of the drum. No easy task!
Left to right, front to back. Electric Brake assembly, spindle. Above the spindle, oil seal, two tapered bearings, another oil seal, a washer, and the castle nut. Below the castle nut, the studs I took out of the drum. Two steel sleeves, 9 bronze bushings, and a 1.5" pulley. In the Back, 7" trailer brake drum/hub, hose clamps set (Harbor Freight), 4.5" pulley and AX-23 belt.
That same day I also went to Washington Belt and Drive where they located the big pulley. It wasn't easy to find one that would be machinable to fit the drum, because most of the ones that diameter were spoked. The Washington Belt and Drive guys sent me to Everett Sound Machine Works to get the pulley bored out and the rough end of the spindle turned down smooth. It was, as we say in the Northwest, Spendy. It cost an hour's machine time to do them both, $60. The two steel sleeves were another $10. One is a bit loose, an the other is too snug. I think the difference is one is an "O" drill and the other is a "P", either side of 8mm. The bronze bushings were $2.81 each, with a 5/16 ID and 1/2" OD. Actually, they're a bit bigger, but that can be fixed.
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See. I told you those studs were a bear. I took my largest vice grip and adjusted it so that it was just short of impossible to close, stuck the drum in the vice, and whacked the end of the vice grips with a 3 lb sledge mallet. Even then it didn't move half the time. Lucky I guessed right on the thread direction. They were so tight, they could have been cast in place. They required the vice grips until the threads were fully disengaged. |
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Nice look at the bushings. Let's play with them. |
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I took the one that was too tight and drilled it out on the drill press (forgot to take photos). You can keep coaxialness by using a snug drill to align the bushing while you clamp it, and then swap in the bigger bit. That vice setting also worked for drilling the pin hole, BUT, the bit was deflected as it went through, so I got to be good friends with Mr. Needle File. I also had to grind the pin down since it was longer than 1/2". The tape is there to keep the filings out of the magnets, I hope. As you can see, masking tape is no defense against a wandering angle grinder. |
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Oooh, that fit so snugly and smoothly, it was almost obscene. Okay, I'll confess, I fired up the motor and held sandpaper and a file to the sleeve until things fit well. |
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Everyone's favorite standby power supply, the battery charger. Handy hint, tie a knot in one of the EV power leads to help avoid the tendency of the clips to want to touch each other and short. |
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This guy fit so snugly, I had to wire-brush all the paint off of the drum, and find the one angle it slipped on at. That's what the index marks are for. Later, I will drill the pulley and tap the drum for a couple bolts to hold them together. Originally, I wanted keys, but the machine shop guy, Joe, talked me out of it. Good thing. I would have had to pay for HIM to take the studs out. Ka-ching! |
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A Vision of things to come. Later on I assembled the spindle and bearings, put the spindle in a vice, and spun up the drum. SCARY! I dunno if this hammer is going to hit hard, but it's gonna make Deadblow look like Grendel when it comes to speed. |
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After doing the steel sleeve, I figured I'd prepare all the bronze bushings for use on the EV shafts. To get them roughly concentric, I first mounted a 5/16" drill and put the bushing on it, and then adjusted the cross-slide vice to clamp it in position. Then I switched in a size "O" drill, which is slightly shy of 8mm (the EV shaft diameter). Naturally they were a tight fit, but as you'll see below, the next drill up, "P" is too large. I made up the difference by clamping the bushing really tightly, distorting the hole slightly and then running the drill up and down a few more times. That actually took it to a perfect fit, at the expense, I discovered later of making the wall thickness uneven. If you're going to do this, go find an 8mm bit. A thousandth of an inch is a big deal when it comes to metal. |
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To avoid the bending problem I had with the steel sleeve, I "Choked up" on the #31 drill. I also eyeballed the drill as it touched the bottom of the bushing and adjusted the cross slide as needed to get a perfectly centered hole. |
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Ta-dah! I marked the one drilled with the "P" drill just so that it gets used LAST if I ever need it. |
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Nice fit. I used the P-drilled steel sleeve as a grinding guide to shorten the pins to 1/2" |
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The outside diameter of the bushings was as much as .003" oversize. An easy way to bring down the diameter (But somewhat time consuming) is to power up the motor and sand. But don't overdo it, and watch out for the incredible heat even 15 seconds of sanding can generate, and wear a respirator unless you like bronze colored snot - and bronze in your lungs. I later cut the paper into slightly over 1" wide strips, which made it easier to keep the tension evenly distributed over the bushing, preventing sanding in curves. Frankly, this is a good case for owning a Micrometer. I detected some that were out of round by a couple of thousandths and filed them back into round. It was easy to tell because the hole through the pulley was REALLY precise. If it didn't slip on and you could rock it, the axis it rocked on was where you needed to file. If you overdid it by as much as .001, it would just drop on to the shaft, and you could wiggle it slightly. The last two, naturally, are the best, totally perfect. There are three bushings left over that I will deal with when I get more EV's. As far as I'm concerned, barring an EV failure, the installation is permanent. |
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To make a first stab at a Motor Mount (And with a stab like this, I'd be better off with a grenade) I grabbed some leftover 1" angle iron from an old bed frame and cut the pieces to size. |
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Here is the core of my motor mount concept. At the right distance apart, angle iron in contact with the body of the EV will also be flat relative to one another. However, some of the motor will protrude beneath that plane. Not an issue. The hose clamps (14.5" of clamp material is just right, and 1/8th of the amount in the package) pass through holes with have been filed to have a flat edge angled to avoid kinking the clamp. The notch for the cap allows the mounting bars to be flush against the sides, while extending beyond the mount - extra insurance that the motor won't slip out. |
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I'm a bit short on intermediate pics. I welded two of those square pieces of bar stock to the ends of the lower mounting bars, then welded the two upper mount bars to it. Later, I cut the lower mounting bars to length, and I will be adding the last two bits of bar stock to close up the end. |
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Just a nice end view. And you can see that I need to be just a LITTLE more careful about alignment when welding, although actually that won't be a problem on this one. |
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Sandblasted all the old paint off. This shows the first two bits of the bar stock. They are important because they will be drilled and tapped for a tensioning mechanism. The lower mount bars will have holes, and then there will be more angle iron with slots cut in it to receive them. |
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Slot cutting will have to wait until I get a Mill. I have a drill press and a cross sliding vice, but even with milling cutters, that setup is nowhere near rigid enough. It's really weird to see something you think is immobile wobbling and twisting. The upper slot is one I tried to cut with milling cutters. The lower slot was done by drilling a lot of holes and then cutting between them with an angle grinder. I suppose it could be done neater, but it's time consuming. A Mill would be better anyway. |
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