Wood Bridge Contest (800 points)

1. Bridge Research Worksheet (100 points)
2. Drawing bridge full scale on graph paper (100 points) 
3. Bridge Construction (100 points each side, 400 points total)
* -2 points for every 1/4" outside the specified bridge size requirements
4. Bridge Testing (200 points) Testing Rubric Below. 

Bridge Requirements 
Length: Must be between 8" and 11" long
Height: Must be between 4" and 8" tall
Width: Must be between 2" and 4" wide

*No parts of your bridge may be solid. (i.e. a finger must be able to poke through any side of your bridge multiple times).
* -2 % points for every 1/4" outside the specified bridge size requirements

Bridge Testing Grading Rubric
A = 40-50 pounds held
B = 30-39.9 pounds held
C = 20-29.9 pounds held 
D = 10-19.9 pounds held (i.e. 10 pounds held = 60 D, 19 pounds held = 69 D)
F = 9.99 pounds held or less


50 lbs. held = 100 A. For each additional pound held, one point extra credit will be awarded. 

Extra Credit Opportunities:
For each additional pound held over 50 pounds, one point extra credit will be awarded. 

quarter.inch.graph.paper.pdf
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A full scale drawing of your truss must be symmetrical! Your road bed (bottom piece) may not fit on the same sheet of paper.

How to safely cut 1/4" sticks for your bridge.

Find some scrap lumber that has no nails or screws in it. The longer, the better.

Set the rip fence to 1/4" and lock it. This is what 1/4" looks like on the fence.

Make sure the blade height is barely above the wood you are cutting.

Use a push stick to cut a 1/4 strip.

Cut the strip into 1/4 rods. You may have to cut half way, stop, and then flip the piece to cut safely. You cannot use a push stick because it will not fit between the blade and the fence.

Hooray, you have a 1/4" rod. You probably need about 20 of them to make a bridge.