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page 51
Bamboo Journal
Italian Bamboo Rodmakers Association
Take an edge where a constant depth groove has
been planed (take notice otherwise). Apply the
two shimpacks, and read the apparent depth
with the guide that holds the dial indicator.
Subtract from the readings the actual groove
depth. The difference should be identical to the
taper. If the groove is not even, take the differen-
ce between the two readings. Again, you should
get the taper values.
The second test is more important and certainly
more useful. We start with the two shim packs
on the form and carry out the planing with the
guide and the luthier plane. If we feel we have
inished, we can check if we have removed as
much as we should have or if we need to insist
on some point. To check, just read the apparent
depth by running the guide with dial indicator
along the bar, WITHOUT REMOVING the shim
packs. The readings must be constant. This test
tells you immediately whether you have planed
well or not. If the readings are constant within
one mil, good! You have done a great job, and
you have inished. If you have removed less here
and there, try going over the beam again and
again, rocking the plane inside the guide. It is
very probable that you will remove very thin
shaving, and accuracy will be improved. Conver-
sely, if you have already removed enough and
insist on removing more, my experience is that
you will fail. Rocking is legal!
5. The animal glues.
A few words on the animal glues you will use to
glue the bamboo strips to the grooves of the
former beam. Actually, this operation will be
carried out after that the strips have been
pressed at the nodes, as described in the next
chapter. I prefer to anticipate the topic of the
glues, leaving the last chapter exclusively to the
working of the bamboo, before and after the
gluing.
First, which animal glue? There are various
types. I suggest the bone glue, usually in the
shape of round little pearls (see the photo).
I advise against glue made from rabbit skin (the
inely ground stuff), as parts glued with it
cannot be taken apart as neatly as with bone
glue.
It is fundamental that the concentration of the
glue is much lower than that used for standard
glueing. I hesitate to give you strict indications
as I have noticed that glues from different
sources have varying adhesion strength. I have
found that concentrations of glue around 5 % by
weight are adequate, but I have bone glues that
at these concentrations give a too fragile bond.
Do your own tests.
The ungluing is carried out with heat. All it
takes is a few minutes, but the parts must be
detached by inserting something (a thin artist’s
spatula) to gently pry pieces apart. The detach-
ment is usually quite sudden. No appreciable
traces of glue are left on the detached parts,
because at low concentration used the glue is
very thin.