Drawbridge

This project was a collaboration between Aidan Emmons and Keaton Wasson

Background and Overview:

We are students at National Park college, and, for our Intro to Engineering class, we were assigned to complete a project, of our own choosing, that follows the 8-step engineering design process. We specifically chose to make a drawbridge, as we thought that it would be a relatively simple, but still very interesting, project. The 8-step engineering design process is a process used to simplify the design process, and help make the design as beneficial as possible. The process and how we used it for our project is as follows: 

1 - identify a need for a project/service. Our need for a project was having to make something for class. 2 - Define the problem. Once again, we just needed to make something for our class. 3 - research the problem and possible solutions. Since our problem was so open ended, we could have solved this in an infinite number of ways, but we decided to make a drawbridge because it seemed fun. 4 - conceptualize possible solutions. We looked at basic drawbridge designs to make sure that the project was feasible. 5 - Synthesize the findings. We determined that the drawbridge would fit our needs. 6 - Evaluate in detail the possible solutions. Once again, we determined that a drawbridge would fit our needs very well. 7 - Optimize your solutions and determine the best solution. We used a drawbridge as the solution, and completed the project. 8 - Present your final product. To present our product, we turned in the project to our class, and posted this Instructable online.

For this project, we had access to the Maker Space at National Park College. The maker Space provided us with many of the tools that we utilized. Special thanks to the workers at the Maker Space, as they allowed us to use the environment and tools.

Supplies and Tools

Wood for the Structure:

Three 12 inch by 4 inch boards of wood. (Used for the frame).

One 15 inch by 15 inch square of wood. (Used for the base).

9 inch by 12 inch piece of wood. (Used for the door).

Rope spool. We used two 2 inch (in diameter) circular pieces of wood glued on either side of a 1 inch tall and 1 inch diameter cylinder of wood, but most spools of a similar height should work the same.

Other Supplies:

Metal hinges. The size doesn’t really matter very much, but the ones we used were 3 inches wide.

Twenty 4 inch screws. (Used for connecting the base to the frame, and the hinges to the frame and door, and connecting the frame).

1.5 inch metal crank. The size and material don’t matter very much, but the aforementioned measurements are what we used. You should be able to bolt the crank to the rope spool, and you should be able to reliably turn the crank without difficulty.

30 inches inches of a strong and thick piece of string or thin rope.

Three 4 inch long bolts. (Used for connecting the pulley to the frame, and the spool to the frame).

One small pulley. These can be found in most hardware stores. The exact measurements don’t matter very much as long as the pulley fits into the frame, and is big enough to hold the rope/string that you decide to use.

Tools:

Drill with all needed drill bits.

Screw the three boards for the frame together with two of the boards perpendicular and on either end of the third board. Once you’ve done this, Screw the newly built frame onto the edge of the board used for the base. The two parallel boards should be the ones screwed in, with the third board acting as the top of the frame. You will need to drill diagonally to attach the frame-boards to the base.

Attach the hinges to the door. This is done by screwing three screws per-hinge through the hinge, and into the door. The hinges should not be at the very edge/corner of the door, but should also remain equidistant. After doing this, attach the door to the base in the middle of the frame.

Drill a hole through the top left corner of the door. The hole should be just large enough to fit your rope/string through. After doing this, attach the pulley to the inside of the frame. This can be done by bolting the pulley to the wood. The pulley should be on the same side as the hole in the door (the left side). The pulley should be near the top of the inside of the frame. Bolt the other half of the pulley near the bottom on the left side of the inside of the frame. 

Bolt the spool, with the crank on top, on the left side of the base, opposite the side of the frame. Then, thread the string/rope through the hole in the door, around both halves of the pulley, and wrap it around the spool. Tie a knot on the end of the rope outside the door-hole to prevent the rope from coming out of the door. Secure the rope on the other end as well. You can do this in a multitude of ways, but we just threaded the rope through the same hole as the bolt, and tied a knot to hold it in place