Home > Robots > Evil Fish Tank! > Part 2
 Part 2

I hate delayed gratification.
   - Johnny Bravo

Continued from Part 1...

With the three cylinders in place, and at a line pressure of 120psi the torque on the ramp would be 720 in-lb. At the radius where the titanium plates started this would be about 70 lb. of lifting force which we expected would be enough to just break the traction of an opponent and give us the advantage.

Also with three cylinders we could tolerate the failure of one during a fight.
EFT was also a good metallurgy experiment for us. It was our first go with 6-4 titanium as well as the chromoly tubing. Ti is a fun metal to work with once you get the hang of it. Here, Tony is using the flap disc sander to put the leading edge onto the ramp plates.
Top view of the EFT before we screw the final sheet of Lexan armor on. Compared to its reincarnation as HAZARD, this baby had plenty of room!
After all the TiG welding was done I took the frame over to Varco to be heat treated. 4130 is about as strong as mild carbon steel in its annealed state so if you try to use it without hardening it up, you're just wasting money on the alloy.

If you're in the LA area give Varco a shot as they turn things around in 24 hours.
The staff metallurgist recommended taking it to Rc42 hardness as a compromise between flexibility and stiffness. However they let it bake in a normalizing operation for six hours to stress relieve all the welds and minimize its tendency to twist out of shape. It did come back a little warped but we were able to compensate for that in the structure of the hinge mounts.
Everything is mounted and adjusted and Tony is doing a final check out before the drive test. Ultimately this baby had to drive like Corvette so that Tony could work some strategic magic out there in the arena.

One of the ramp height tests on a piece of paper on the floor. No this wasn't staged! And you can listen to the motor whine during acceleration (32K).
It's hard to know when you're done on a project like this, but since all the major tasks were out of the way a week early I had time for some fun. So I milled up a cool little spring-loaded access door for the main power switches.
A final view of the back of the robot with two big magnesium plates screwed on. Our scale said we were right at weight with them so we planned to leave them on unless we weighed in over.

The blue cylinder is a 120,000uF noise capacitor that we planted right on the main power terminals of the Vantec. It clamped out a bunch of motor noise that was simply driving us nuts.
A few days before the event I was contacted by a reporter from the Arizona Tribune newspaper regarding a big BotBash story. He asked for some photos so my coworker Scott snapped these out back behind work during lunch. They ended up running on the front page of the "480 Living" section.


Well we ended up sweeping the entire 25 kg. category after defeating robots AlphaRaptor, Gator, Knome II and Backlash. We won all possible points as listed below:
            Obstacle Course   Capture Flag Battle Bonus Total
Rank Master Robot Robot # Time Penalties Final Time Points Points Points Point Points
1 Tony & Dan Evil Fish Tank 23 17.31 0 17.31 60 70 80 0 210
2 Dennis Millard Gator 17 12.38 12 24.38 55 70 75 0 200
3 John Pagano Green Dragon 22 23.7 30 53.70 30 70 70 0 170

Our only mechanical failure was a broken weld on the chromoly due either to us ramming someone into the wall at an oblique angle, or Tony accidentally hitting it with his beer. It compromised the geometry of the frame and popped the screws holding on the titanium ramp plates, making it look like the EFT fell apart in the arena. Pretty funny!


"We rocked!" Hey it was a great weekend and our design was proven. Thanks to the BotBash sponsors Vantec, Netmedia and RobotStore for the great loot, too.

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