page16
page 52
Bamboo Journal
Italian Bamboo Rodmakers Association
A problem that must not be underestimated is
that the operations have to be carried out
quickly, before the glue forms gels. At the low
concentrations, the process grants quite a few
minutes, about ten. The strips must be tied with
rubber bands, joined together in a string. For
short sections, it can be done by hand, by rolling
the beam while keeping the rubber band taught.
It is very useful to fasten wooden screws on one
of the sides of the beam to hook up the ends of
the rubber band string. For security, tighten the
screws well, leaving just the head proud of the
beam surface. An example of a bar with strips
blocked by rubber bands is shown in the photo
below. Also notice the end of a rubber band
hooked to a wooden screw.
Due to the excellent coupling of the curved
surfaces, it is very easy to slide the strip side-
ways to be sure that each groove is covered well
from edge to edge by the bamboo strip. It is also
easy to slide out of the groove any imperfection
in the bamboo that are near the edge of the
strip.
6. The working of the bamboo strips.
What makes the revise former beam method
unique can also be appreciated by the fact that
we do not speak about bamboo until the last
chapter. Indeed, we only see the bamboo in two
distinct phases, pre-gluing and post gluing.
The pre-gluing operations, after the splitting,
are concentrated on working the external
surface of the strips only. This involves irst the
treatment of the nodes with a heat press. The
vise is a good quality vise that closes without
play or transversal movements. One of the jaws
is covered by a movable jaw with a cylindrical
shape and a radius close to 25 millimetres. It is
built with pieces of pipe with an external radius
of 25 millimetres glued one inside the other
with epoxy resins. The inserts that will press the
heated strip have a groove to it the lip at the
node. See the igure below.
The pressing of the nodes guarantees that the
radius of the bamboo is brought to a standard
radius. Between the nodes the radius may
change some, especially if the section of the
bamboo culm is slightly oval shaped.
To guarantee that the radius is exactly the same,
I suggest you work the entire strip surface with
a piece of pipe identical to the one used for the
vice. Use this template to sand the external
parts without fear, starting with an 80 grit grain,
and then decrease the grain for the inal passa-
ges. You will notice that, if the bamboo is good
quality with a generous diameter, the material
removed comes from the edges initially. Stop
when you have justnremoved the enamel from
the central part.