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Trebuchet
(page 1)
(114,453 bytes; completed unit)
In December
2002, heavy snow tore off a branch from a small maple tree
in our back yard. It was two months before a (relatively)
warm spell allowed us to take a close look at the tree. Unfortunately,
there was a decent amount of damage to the tree so we decided
to cut it down when time allowed.
(336,339
bytes; broken branch in foreground)
We cut the
tree down in February 2003 and it sat in the garage for over
a year while I debated its fate. Nothing worthwhile surfaced
and eventually, I gave the large parts of the tree trunk to
my neighbor to burn in his wood stove. I kept some of the
smaller stock just in case I came up with an interesting project.
Then one
day, for no particular reason, I decided to build a trebuchet.
I begin
each project, big or small, the same way - by defining the
goals. For the trebuchet I wanted:
- something
that would be rustic in appearance
- make
use of the maple sticks
- make
use of any other leftover lumber I already have
- be inexpensive
- work
well
While the
actual total construction time was only a few hours, it took
place over the span of many weeks. Small incremental steps
were taken with pauses in-between to consider the next steps.
(306,861
bytes. The original stock of tree branches)
(294,655
bytes. Stripping and shaving the tree trunk. The smaller branches
made an even bigger mess)
Before
use, the bark from the maple tree was stripped. This actually
took place shortly after the tree was cut down. Suffice it
to say that the process made a mess and since it was winter
at the time, the bark didn't exactly peel off easily.
(301,628
bytes. The pile of sticks to work with)
Taking
into account the available maple stock, I selected pieces
for the major parts of the trebuchet. First was the arm -
it had to be relativelty straight yet be stout enough to support
an axle, weight and rotational forces. The length of the arm
defined the rest of the dimensions.
(304,403
bytes, 283,232 bytes, 284,691 bytes, 307,651 bytes, 330,165
bytes respectively. Left to right are the steps taken starting
with the frame, the verticals, the side brace, front brace
and back brace)
The
basic frame consists of 5 pieces of maple connected with lag
screws. Two vertical posts support the main horizontal axle
for the arm. These posts are braces on three sides to handle
the large stresses of launching a projectile.
5-November-2004
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