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POST
2
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I
put the back on the sides first; so this second post will document
preparing the back wood and bracing it. The back wood is also
Koa and was cut from the same tree as the side wood. Again we
will be using a book matched set of Koa boards for the back.
The joint where the two boards will be glued together must be
straight and flat. I use a small block plane to get the two
edges flat and straight for joining. |
I hold the two boards together and pass them over a strong light.
When no light shows through the joint; the two boards are glued
together using the jig in the photo below.
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The
back has been glued together and sanded to .080” in the photo
below. You can see the mirror image that is the result of glueing
together two boards that were sequentially cut from one board. |
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The
Back has been cut to shape and a reinforcing strip of spruce
is glued over the joint of the two back pieces. Small sections
of the splice have been removed for the cross braces that will
strengthen the back. |
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Two
of the back braces are being glued to the back in the picture
below. I’ll let them cure for a couple of hours and then glue
the other two using the same fiberglass rods to hold pressure
as the glue drys. The braces are glued to the back before being
shaped. This is done for two reasons: 1. To present enough top
area for the fiberglass rods to hold pressure without slipping
off of the brace and 2. |
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It allows the builder to tune the back or top as he is shaping
the braces. This tuning of the back or top is more important
with the top and I will elaborate on that when I post the bracing
of the top. |
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Shaping
the back braces starts with bringing them down to the correct
height. A few minutes with a small block plane piles up the
shavings.
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Each
brace is shaped with a very sharp chisel and then sanded smooth.
The first two braces have been shaped and sanded in the picture
below.
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All
four of the back braces have been shaped and sanded.
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