Yixing Shi Ruthika Iswara Li Yen Ng
Our design consists of a rectangular base to support a triangular truss structure such that it contacts the weight without touching the ground or the wall. Our servo is attached at the other end of the truss to lift our weight. A long lever arm with a counter weight attached to the end of the arm is employed to lift the weight using the torque supplied by the servo.
In order to lift the weight initially, the motor needs to produce a torque of 32.9 oz•in clockwise. Since this is only 45.7% of the maximum torque that the motor can supplied, the motor should be able to lift the weight.
The theoretical height that the weight can possibly reach is 3.35in. The mechanism managed to lift about 3 inches at the final review. Therefore, our calculations are accurate.
Unlike the more common rectangular truss, we used a triangular truss as we can create a truss that is just as sturdy with less material. This helps to reduce the overall weight of the mechanism.
We also decided to attach the truss to the base slanted at an angle. This is so that our long lever arm can hang off the table without touching any part of the table.
We also decided to combine two different kinds of materials for the lever arm. When we used Aluminum strips of the same length for the lever arm, it flexes easily at the point where it touches the weight and does not lift the weight. As we need something that is light and stiffer, we decided to use the delrin strip just for the section of the lever arm that touches the weight. The rest of the lever arm is made of the aluminum strips thinner and lighter aluminum strips so as to reduce the overall weight.
We decided to make the lever arm long and also attached a counter weight at the end of the lever arm so as to reduce the amount of torque needed to lift the weight.