Plywood Bridge

Overview

Your task is to build a bridge using 1/8" thick plywood and wood glue only. Our objectives are that you will learn how to use 3d design tools, a laser cutter, and also that you learn a bit about structure. This project is inspired by the "toothpick" bridge project (google it).

Requirements and constraints

Your bridge will cross a void between two pillars that are provided. Each pillar is 2.5" x 2'5", and they are separated by 7.75" (see diagram). You are to design and build a bridge that meets the following constraints:

• It must span 7.75"
• It must fit within a 12.75" x 2.5" x 8" space.
• No portion of the bridge may extend below the surfaces the "feet" rest on.
• There must be a 2.5" x 2.5" pad centered at the top of the bridge upon which weight will be applied.

Materials

You may use only the following provided materials:

• One piece of 1/8" by 12" x 24" plywood
• Titebond wood glue

Process

We will have at least the following milestones, which will be confirmed with “skill-demos”:

• Example hardcopy of something output from CAD software – confirming that you have successfully accessed some CAD platform.
• Initial 3D design of your car (not perfect, but initial).
• File suitable for lasercutting wood. And cut wood.
• File suitable for 3D printing, and a 3D part.

Details on these skill demos will be provided and refined via the course wiki and t-square.

3D Printing

You can export 3D part models as .stl files and print them on the GVU 3D printer. Most of you will be unfamiliar with the process, and can come to the GVU Prototyping Lab during the ‘lab hours’ or at other times when your TA is available to help you.

Laser Cutting

You can design a chassis as multiple flat parts that interlock and will be glued together. These parts can be designed as an assembly in your CAD software. Once you have them laid out, there are multiple ways to export them, but we recommend laying them all out at 1:1 scale in a drawing, and exporting that drawing as a DXF file. This can then be opened in Illustrator on the laser cutter computer. Again, for assistance laser cutting, come to the GVU Prototyping Lab during the ‘lab hours’ or at other times when your TA is available to help you. You may also consider use other laser cutters on campus, including the ones in the Invention Studio.

Iterate

There’s a fair chance that your first design may not work as expected. You may want to assemble your car with masking tape at first to test the design before using more permanent wood glue. If you’re pressed for time, you may also consider hot­melt glue as a weaker but faster option. Also consider being careful with your plywood usage in case you need to re­cut your entire car.