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Glue
The
first glue we use is "Gorilla Glue." We like Gorilla Glue a lot because
it is light and strong. But it does need to be clamped very tightly,
so we only use it to glue the bridge sides together.
We clamp Gorilla Glue by laying the balsa pieces flat on top of each
other on the table, and then placing a telephone book on top of them.
We then place a water bottle on top of the phone book. We use
"Elmer’s Carpenter’s Wood Glue" to glue the bridge sides together.
Carpenter’s Wood Glue isn’t quite as strong as Gorilla Glue, but it
doesn’t need to be clamped as tightly either. We use rubber bands to
clamp the bridge sides together. In the actual competition, we didn’t
use the new bottle of wood glue. We used the old bottle. It is 40
years old and belonged to my great-grandfather. I’m not sure you can
buy 40 year old glue in shops, so I used the new bottle for
the bridge in the video.
Clamps
It’s
often helpful to have a pair of clamps so that the wood doesn’t move
when you’re working on it. But you usually don’t put the clamps
directly on the piece of balsa wood. Instead the balsa wood is
sandwiched between your work surface and a piece of scrap wood. Kids
often have trouble putting the clamps on, so ask an adult for help
in doing this.
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