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 EquipmentNot 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 itselfAs long as you use glue for what is was designed it might not really matter
5 CA Glue (aka superglue) – High School Use Dries quicklyVery strongComes off your fingers naturally within two weeksMust use in a ventilated areaExcellent for gluing two sides together!
6 Wood Glue – Middle School Use Good brand of wood glueThree types availableClamp for ½ hourWater clean upExcellent for laminating beams together
7 ToolsAll 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.
12 PlanningThe 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 symmetricGlue 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 clipsAlternate the clips so that the beam does not warpSand 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 storeDon’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 neededNote 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 minutesSeal in a plastic bag after bakingBake 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 itBe very careful not to burn yourself or your teammates!Never pin through the wood!
23 Types of Joints Gussets improve a joint End joint (weak) Lap Joint (best)Notched Joint(better)
24 Loading your bridgeYou 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!