This week we’ve been working on a function to tilt the gun. Our primary focus was elevating the barrel but we also tried to keep in mind how to easily expand on our design in order to allow the gun to rotate horizontally. After a session of brainstorming we concluded that a motor with a pinion in contact with a larger spur gear would work how we wanted.

By driving the motor it’s gear would mesh with a larger gear attached to the same board as the gun. This would in turn rotate the top board about the holes in the brackets.

We found a 12V 60 RPM motor but required a small gear for the shaft. We had problems finding a pinion that would fit so we were forced to buy one with a smaller hub (3mm) and then drill the hole larger (4mm).

Because this motor was going to tilt the top board we had to think about what would happen when the motor wasn’t running. The location of components on the top board would create a moment that had to be resisted by the motor. Therefore to keep this moment as low as possible the center of gravity (longitudinal direction) of the gun would have to be placed on the same line as the axis through the bracket holes. This is illustrated by the line and arrows.

When the placement of the gun is determined we can reduce the length of the top board accordingly.