During the second week, we ran into some challenges attempting to make snap-fit connections on our chassis frame. The goal of this exercise was to design, create and test the snap-fit connections using acrylic and delrin.
Above are two attempts at designing and laser cutting the snap-fit prototypes. As you can see, the attempt on the left is much thinner and proved to work as well as the one on the right. We moved forward with implementing the snap-fit on the right into our chassis frames.
We first cut these chassis frame pieces out of acrylic to test the durability.
The photo above shows how some on the teeth on the snap-fit joints broken off. This form is what the frame would have looked like if the snap-fit connections had worked.
The second attempt we cut our the chassis frame pieces using delrin. We assumed the delrin would allow for some flexibility on the snap-fit connections. As you can see in the photo above this is what the frame would have looked like if the snap-fit connections had worked.
Ultimately the snap-fit connections on both the acrylic and the delrin failed.
In our first week, we were introduced to assignment 1. In this assignment Stephen and I disassembled a wind-up toy dog to investigate the mechanics and document all of the parts. The exercise and findings are explained in more detail below.
Our first steps in understanding the wind-up toy dog, was to disassemble the dog and label all of the parts. The 23 parts are laid out and labeled above. The parts ranged from large shell pieces (spine, butt, tail, belly, ears and face) that created the body of the dog, all the way down to small gears inside the gear box that enabled to toy to function.
In order for the toy to work properly, all of the parts must work together. As we were disassembling and reassembling the toy we were able to realize how the toy functioned. As you wind up the toy with the crank shaft, the spring inside the motor is tightened. This motion interacts with the ‘S’ gear that is connected to the spring. The ‘S’ gear reacts to the springs tension and moves the large white gear, which is located on the same axle of the crank shaft and connected to the ‘S’ gear. Once the crank shaft is released the white gear then begins to lock into the grooves of the blue gear and begins the motion of the gears. The grooves of the blue gear move the small white gear and that in turn moves the small blue gear. The escapement catches the small blue gear to slow the rotation of the gears. All of the gears are held in place by the motors casing. These gears are connected to the leg axle. This leg axle begins to move the left and right axle cap in a circular rotation. The axle caps will then move the toy dog’s legs and ultimately make the toy move, as seen in the video above.
LIASON GRAPH (SIMPLE)
LIASON GRAPH (ADVANCED)
The assembly of the toy dog’s body or outer shell was not difficult to disassemble or reassemble because these pieces were held together by three screws and a few peg connections. The ‘guts’ or interior area of the toy was definitely the most difficult area to disassemble and assemble. The motor was so interconnected that they each part was placed together with perfect precision. Once we begin to disassemble the outer casing the interior gears lost their precise connection and begin to unravel. These gears and pieces even when reassembled didn’t match the tight construction that they once had. Even when we put the gears back in place and closed the motor casing, we noticed it was not assembled as efficiently as it was to begin with. This inefficiency caused the toy to not function as well. The motor was by far the hardest area in the assembly sequence.
