1. How to build a bridge!

2. The Romans frequently built bridges with several small arches on top of one another.
This slideshow contains tips, hints and several interesting bridge designs.

3. Tools and Equipment
Not all of this is necessary, but all of it is very helpful.
“One only needs two tools in life: WD-40 to make things go, and duct tape to make them stop.”
-G. Weilacher

4. Use the glue you are given!
Most glue is stronger than the wood itself
As long as you use glue for what is was designed it might not really matter

5. CA Glue (aka superglue) – High School Use
Dries quickly
Very strong
Comes off your fingers naturally within two weeks
Must use in a ventilated area
Excellent for gluing two sides together!

6. Wood Glue – Middle School Use
Good brand of wood glue
Three types available
Clamp for ½ hour
Water clean up
Excellent for laminating beams together

7. Tools
All of these tools are recommended but be careful as they are sharp and can injury you if used improperly.
Scissors, ruler, square, level, and sharp blades

8. More tools Binder clips make excellent clamps (and are cheap)
You need a sanding block and plenty of sandpaper.

9. Even more tools… Files will help you to shape the wood.
Pins are available at hobby stores. You must have many.
A 3/32” square file is particularly helpful in making notched joints.

10. This is a ceiling tile that has been glued to a thin piece of wood.
The wood keeps it level and prevents pins from pushing through.
A ceiling tile works very well to build on. It provides a level surface that you can pin into.
Alternatively, you can use several sheets of cardboard stacked together.

11. How To Build Your Bridge

12. Planning
The success of your bridge is roughly 50% design and 50% construction!
A full scale template is highly suggested.
Use a ruler and make your plan full scale and symmetric
Glue sticks together to make an actual-size ruler – two thick, three thick, etc.

13. Tape your full scale plans to the board and pin a piece of wax paper on top. Plan templates are available from me!
The wax paper prevents the glue from ruining your plans.

14. Use your balsa sticks wisely as you can only use the materials you are given.
Glued joints will be stronger if you pre-sand all of the wood.
Choose the best pieces of wood for the vertical and horizontal major components.
Darker wood tends to be brittle but stronger.

15. Construction Take care to make good joints.
When you are done, gently sand it.
Extra glue adds weight, but not strength.
Make sure to follow the gluing directions!
Take your time!
CA glue is a solvent for itself. That means if the glue has cured, don’t add more or it will dissolve itself.

16. Make the beams first.
Each beam is clamped with binder clips
Alternate the clips so that the beam does not warp
Sand each beam until it is flat after it dries

17. Make each side one at a time
The aluminum pins are available at any hardware store
Don’t pin through the wood!

18. Complete each side and then remove it from the wax paper
Leave the pins in place for the second side to insure that they are identical

19. Put the sides together and cross brace them
Sand the entire bridge!
Insert gussets where needed
Note that this design has an undertruss which is not allowed in this year’s competition!

20. Baking Your Bridge!
You can loose A LOT of water mass by baking your bridge!
Low setting for about 15 minutes
Seal in a plastic bag after baking
Bake at your own risk!

21. Bending Wood To bend wood, soften it first over boiling water.
Steam softens wood.
Bend, pin in place and let it dry.
After dry, glue it
Be very careful not to burn yourself or your teammates!
Never pin through the wood!

22. Truss Designs
Howe Truss
Warren Truss
Pratt Truss
K Truss

23. Types of Joints Gussets improve a joint End joint (weak) Lap Joint
(best)
Notched Joint
(better)

24. Loading your bridge
You have 5 minutes to place your bridge on the load frame and position it with the loading bucket.
You have 20 minutes to load your bridge to failure.

25. Good Luck! Bridges are rated on efficiency.
Your bridge needs to be light and strong!
Awards are given for the top 3 teams in both divisions.
Judge’s Choice award will be given at the discretion of the judges.
The high school winner may receive a $1000 scholarship if they choose to enroll at UMKC in the School of Computing and Engineering!