All the parts for Ally's shell were cut using a mitre saw and then pre-drilled in a drill press. The aluminium was polished with Silvo silver polish and then painted with several coats of Incralac metal lacquer to preserve the finish.
The motors and battery are installed using brackets and supports cut from aluminium channels and angles. The battery is a 6 volt 10 amp hour sealed lead acid battery maintained by an on board charging circuit based on the UC3906 integrated circuit from Texas Instruments. The motors are Hitech HS815 Sail Winch servos modified for continuous rotation. Hobby servo motors don't get much more powerful than these. The wheels are directly bolted to the servo splines, which is ok so long as the robot is not carrying a load. This will have to be upgraded to a chain drive in the near future.
The bump sensor can be retracted and locked in a closed position. The moving parts are lubricated with molybdenum grease and bolted together. The nuts are prevented from undoing using a thread locking compound from Permatex.
The micro-switches mounted on the base of the bump sensor are triggered as soon as the bar strikes an object. Even when travelling at full speed the robot has ample time to stop using its active braking system.