Hollow building a bamboo fly rod means
exactly what you'd expect: Material from the inside of
a bamboo rod is removed leaving open spaces within.
The purpose of removing the material is to make the rod
lighter in weight and make it rebound and recover quicker
with less bounce and excess vibration. There are many methods of hollow building. Most
methods have disadvantages, the most severe being a
significant reduction in the overall strength of the rod.
I have experimented and made rods with every type of
hollowing I could find - straight-cut, fluted,
star-hollowing and scalloped. After testing these rods
I have come to the conclusion that the best method, for both
improvement in action and overall strength, is a method
first described and developed by EC Powell. Powell
actually patented the process which you can see
here.
Simple scalloping involves removing small ovals of the
softer, inner pith of a beveled and shaped bamboo strip.
By mirroring the ovals on each of the 6 identical strips of
a hexagonal rod (or 4 strips for quads) you end up with
small hollow ovals inside the finished rod. This
method of manufacture is, as a friend put it, the closest to
original OEM specs of a bamboo culm. In other words,
like a culm of bamboo, there are hollows that are reinforced
by dams throughout the length of the culm.
| This photo shows a side view of a
single bamboo strip that has been scalloped (approx.
1" long). |
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| This photo shows what half of a rod (3
strips from a hex rod in this case) looks like when
scalloped and assembled. Take this half and
it's matching twin and you have a finished rod. |
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Of course that is not the end of the story. The next
step is to vary the length and wall thickness of the
scallops, or hollows, inside the rod in order to improve
specific desirable qualities. Longer, thin wall
scallops are better suited for the thinner tip portions of a
rod while shorter, thicker walled scallops keep butt
sections from becoming weak or too soft.
I have designed a complex mixture of scallops with different
wall thicknesses, dam thicknesses and lengths and optimized
their layout for each section of a rod from under the grip
to the tip. This gives, what I believe, is the greatest
benefit of hollow building while retaining the strength and feel of bamboo.
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