R/C Tank Combat

Tank #T005

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Here's the servo-trigger interface.

Here's a close up of the upper tube. This metal is not needed for gun operation so was removed. I would not recommend removing the metal from the lower tube the way I did. It was a pain to do and I think it will reduce the hammer O-ring life. But it does allow me to show you ...

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The internal trigger mechanism. That triangular piece of metal sticking up from the bottom is the hammer retainer (the hammer is the thing on the left with the spring is going into it). This engages a notch on the bottom of the hammer when it is cocked back. I ground this retainer and hammer notch to reduce the trigger pull, which is considerable on this marker. I did this because I felt as is, it would have been difficult to get the trigger servo to easily depress the trigger. A word of warning ? If you attempt to modify your markers trigger pull in this way, you may make your gun un-usable. It took several tries at re-grinding to get this marker to work after I first mucked with it.

This is the hammer in the cocked position.

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Here's how to mount the trigger servo to the marker. The screws securing the aluminum plate to the marker are threaded into holes that originally had plastic retaining pins, which held the trigger/handle assembly onto the marker.

The marker elevation is handled by the cog pulley and belt shown here. The belt is trimmed in such a way so that both ends can overlap each other on the forward side of the pulley. The belt ends continue either up or down, wrapping onto the wooden block and secured with monofilament. The block is glued and screwed to the gun mount. Turn the pulley one way - the marker points up, turn the other way - it points down.

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After destroying one of my motors during a "simple" bearing replacement, I had to find some new ones. I opted for some BattleBot technology and acquired two "EV Warrior" motors. The new motors are about twice the diameter of my old ones and they were a tight fit into Tiger Killers engine bay. EV Warriors have powered many a BattleBot to victory. I imagine they'll do the same in R/C Tank Combat!

EV Warriors can suck up the amps (100amps at stall). I felt that standard 30/40 VF4 series relays wouldn't be enough to feed these beasts. I found these H-Bridge 70amp relay modules on eBay. So far there working great.

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Click Photo For Enlargement (79 Kb)
Due to the design of my relay modules, the Tri-Pact diode mixer could not be used to control them. What you see here is a prototype PIC microcontroller based relay mixer provided by Joe Sommer at Anvilus Machine Works. Besides controlling the drive relays, this mixer has four additional outputs to control such things as turret rotate, elevation, and whatever you can think of.

My receiver and mixer are mounted inside the turret. To connect the mixer to the drive relays I used a cord from an old IBM AT keyboard. The keyboard cord is very flexible, has four conductors, a shielded ground, and is perfect for this application. The cable running through the keyboard cord is the 12volt feed for the turret rotate motor. The connector is a standard DB9 computer connector.

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