Balsa Wood Bridge

this build is a Balsa wood truss bridge made with 1/4 times 1/4 balsa wood sticks, Gussets made from paper index, cards and wood glue. the bridge is 18 inches long 2.5 inches wide and 4 inches tall. the bridge uses a k truss design that i initially designed in autodesk inventor.

materials: Balsa wood sticks, index cards, Wood glue

Tools: Balsa wood cutter, scissors, Wooden clips

Autodesk inventor

i first used inventor to create a solid trapezoid shaped block using the sketch and extrusion tools , then i sketch the design of my trusses on to each face of the trapezoid shape. after which i used the frame generation tool to create the finished model of the truss. the last 2 pictures are of the bottom view and the side view of the model. i used a k truss design that faced outwards from the center and verticle support beams for the side and a simple x shape for the bottom

next i used the frame analysis tool to run an analysis on my model to tell me where my bridge would potentially be the weakest and which parts my need reinforcement

i started to build in this step, first i would place a cut piece of paper gusset on a flat table top, add wood glue the place cut pieces of balsa wood on to the gusset glueing them together the i would add another gusste in top of the glued pieces for more stability and ease of handling, i would do this until i had a section fully completed then repeat with the other sections the first picture is the top section . once all sides were completed i would apply wood glue to the borders of the bridge pieces then hold them together with wooden clips until the glue dries and the piece are adhered to each other like the second 2 pictures show. i do this until all bridge pieces have been glued

next i need to remove unneeded gussets i do this by simply carefully ripping of the gussets from the bridge and glue, this does not affect the actual bridge’s stability.

this project in total took around 1 to 2 weeks for completion the attached pictures are of the finished truss bridge, i added many extra horizontal supports to the top of the bridge for a better and more stable bridge, the bridge weighed nearly 50 grams and could support more than 30 pounds of force without breaking