| Use a small balsa wood saw (about $3) instead of an exacto knife to make cuts |
| Cut small notches to connect bridge components |
| Use a basic carpenter's glue |
| Yellow glues contain aliphatic resin, used in the majority of winning bridges |
| Fewer pieces mean fewer problems |
| Keep pedestals (feet) simple |
| Clamp glued pieces for about half an hour (use protective strips to avoid damaging the balsa). If you don't have any clamps you can use clothes pegs. C-type clamps are available quite inexpensively at Canadian Tire |
| Design for strength at the load application point |
| Construct roadway of thin, narrow strips of balsa |
| Don't glue down ends of road ways…they usually bend upwards under load |
| Use minimal support under roadway, except at load application points |
| Roadway must support a small Hot Wheels-type car |
| Most bridges bend inwards (as viewed from one end); consequently they require horizontal bracing |
| Write your team number prominently on a main horizontal beam of your bridge and on both sides of the bridge |
| Double check that a 40 cm-long board will fit between the pedestals (feet) of your bridge |
| Double check that a 5 cm cube will fit underneath your bridge and along your roadway. You can make a nearly perfect 5 cm cube from Lego bricks |
| Do not cover your bridge with any material. Glue should be used only to join components |
| Use light sandpaper (number 150 or higher) to gently clean your bridge and remove excess
glue |
Some common mistakes: Using a single sheet of balsa for roadway (solution: cut into strips) |
| Making outside width 5.0 cm instead of inside dimension |
| Making overall length 40 cm instead of span (between pedestals) |
| Forgetting 2.0 cm height requirement at 40 cm width |
| Not allowing room for bolt(s) on test frame |
Buying balsa wood? Check out our list of local (Vancouver-Burnaby) suppliers.
Copyright 1980-
Peter L. Vogel