The weapon system for Deadblow 1999 was a 6.5 lb machined steel sledgehammer which swung 180 degrees. It was powered by a Bimba rotary pneumatic (air-powered) actuator with a working pressure of 150 psi. I machined the hammer head out of mild steel. The arm and mounting bracket were fabricated out of 6061 aluminum. The rotary actuator was double-acting, meaning that it was powered in both directions (a single-acting actuator would need a spring or other means to return it to the rest position). This allowed for multiple rapid strikes, without having to wait for a ratcheting winch to reel the arm back or lose power pushing a spring forward. The air was provided by two onboard carbon fiber-wrapped high-pressure aluminum air tanks designed for use in paintball. Although competition rules in 1999 limited onboard air pressure to a maximum of 1500 psi, the tanks were both rated for 3000 psi. The 1500 psi was regulated down to the working pressure and routed to a 12 VDC solenoid valve which I controlled from the transmitter by an R/C relay switch.

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This is a side view of the hammer in its retracted position. The arm has lightening holes machined into it and has a steel plug with a key at the bottom connecting it to the actuator. The hammer head has a bracket welded onto it with holes for the two 3/8"-16 bolts that secure it to the arm. When at rest, the hammer actually folded into the body, which was a cool feature.

I made the fancy lightening holes you see in the mounting bracket with the CNC machine. The mounting bracket was necessary for two reasons: first, to raise the actuator to the desired height, and second, to provide support for the rotary output shaft, which hung out horizontally from the actuator body.

In this picture, the mounting bracket has been removed, so you can see the rotary pneumatic actuator. It is basically a rack that is pushed back and forth by two air cylinders (shiny cylinders located on either side of the squarish block). The rotary output is provided when the rack drives a pinion that is connected to the output shaft.

In this closeup of the hammer head, you can see the weld seam for the hammer bracket. I spent a good deal of time on the lathe turning down this part and producing the high finish on the head. Why? No technical reason, just so that it would look cool. The tip started out pointed, but then I decided to blunt it and go for shock damage rather than piercing damage. By the way, those are Grade 8 flange-head hex bolts - I didn't want the head flying off into the lexan walls of the BattleBox.

This is a picture of the big-ticket items: the drive motors, carbon fiber aluminum air tanks, and rotary pneumatic actuator. Here you can see the pressure guages and regulators on top of the tanks and the rotary output shaft on the actuator with the black rubber cap. And when I say "big ticket items," I mean the tanks were about $400 each, the actuator was $275, and the wheelchair motors were about $250 each.