After having this page up almost one year, I have had emails from
all over the world asking for a tip or advice about toothpick bridge making.
Lately there are several who have had great success, but the one that
warms my heart the most is an entry from Australia. I have decided to
get pictures so that those of you who are facing this task can plainly see
that it can be done, and done well.
I also will have a mathematical explanation of deriving the catenary,
and I would like to make an unabashed plea to those of you who find
this page interesting. BUY SOMETHING!!! Either that, or design a
catenary crosswalk when you become a famous engineer/bridgebuilder!
Chad who emailed me from Western Australia had so far done the coolest bridge I have
seen. ( it looks familiar, you know) The single picture was taken AFTER
testing. He wrote and said, " I believe we could have stood on it" and it
did not break. Grade? A+.
Chad, and partner Jonathon, are 13 and live in Cottesloe, Western Australia.
...The requirements for the bridge were:
To be constructed from wooden kebab
skewers. We could use a hot glue gun or
similar and light string could also be used.
It was to be capable of spanning a gap of
1 metre (just over 38 inches) and hold at
least the weight of one house construction brick.
Ours was not tested till breaking point
but we did put 4 bricks on it and it didnít
even budge. We used dental floss to hold
the flex in the bridge while we completed the
construction but found that we could remove
it once the bridge was completed.
We also used three skewers thick for
the whole construction gluing them both sides
for extra strength. We tried to follow your
instructions as much as possible and didnít
we have a fantastic result!!
Most of the bridges from our year broke.
Some flexed and just survived but ours
definitely looked the most spectacular. We
did spend 5 or 6 afternoons working on it
but it was worth it.
Thank you for all your help along the way.
Chad's Bridge in Australia
Another example of fine work came from my dads old stomping ground,
northern Minnesota. I couldn't believe the coincidence when I got a question
from a high school student in Fosston, Minnesota. A neighboring town to my
fathers home town.
Dad would be proud to help a young 'engineer-to-be' with his physics project.
You can see the 'set-up' for testing here allows the bridge to exert a force on
the table laterally as well as vertically. This is important to know when designing,
but I prefer the bridge be entirely responsible for lateral forces.
Andy's Bridge in Minnesota.
Construction technique is of great importance to success.