Plans for my bridge
Elmers Wood Glue
1-2 boxes flat toothpicks
Heavy duty scissors
Flat surface for construction
I began my bridge by constructing 2 ladder-like bases, one for the top and one for the bottom.
Top: 7 inches in length
Bottom: 9 inches in length
To do this I glued the flat toothpicks together (flat side to narrow side for greatest width and strength) overlapping at pressure points to form a straight line. Each line was 4 toothpicks thick. When I reached my desired length I cut the ragged edges with the scissors to form a more uniform structure. 4 total structures are needed: 2 of each length. To connect the base structures together I glued 2 toothpicks (flat to narrow for maximum width) and cut each glued pair to 1 & ½ inches. I glued each (1/2 inch apart) perpendicularly between the 2 base structures to form a ladder-like design. I let the bases dry overnight.
My second task was to connect the bottom base to the top base in such a way as to strengthen the pressure points of the bridge. I glued 2 flat toothpicks (flat side to narrow side) together to form a wide support. Four supports (1 for each corner of the bridge) were necessary. I cut each support 2 inches long. To ensure stability of the supports I used the excess (1/2 inch) toothpicks I had cut to glue perpendicularly to the top and bottom of each support, thus forming an upper case "I" shape. I glued one(at approx. 15-degree angle perpendicular to the base) to each corner of the top base. I then glued the bottom base to each support.
Next I extended 2 similar supports at each corner of the top base to 1 inch below the bottom base. One support was perpendicular to the top of the bridge, while the other was at a 15-degree angle in reference to the first. This formed the legs of the bridge, and provided for extra support of the top base. I made an "X" shape support for the bottom base by simply cutting 2 2-inch single toothpicks and gluing them to each corner of the bottom base and extending them diagonally to the bottom of the opposite leg of the bridge.
For extra support in the center and outside edges of my bridge I glued flat toothpicks together to form strong 2 inch weight supports. I glued them from the under side of the top base diagonally to the bottom base in alternating directions, thus making a triangle pattern along the length of both sides of the bridge. In the center of each triangle I glued a single 2-inch toothpick from the vertex of the triangle to the base. Lastly, I connected the top base to the bottom base through the inside of the bridge. Between every other triangle pattern I glued an "X" shaped design of double toothpicks extending the width and height of the center of the bridge.
Copyright © 1995 Mr. Lewis Classroom for Physics & Biology. All rights reserved.