Making the mould.
Click on the image to see a larger
picture
There are different methods
for supporting the ribs whilst making a bass. Some luthiers use a bottom
board alone whereas others use some form of mould. The one I use is based
on the design shown by HS Wake and consists of three sections separated
by spacers.
The top and bottom sections
are identical and follow the profile of the body of the bass with sections
cut out to receive the corner blocks and top and bottom blocks. The middle
section is shaped to take steel angle brackets used to support the blocks
whilst the ribs are being fitted.
Care must be taken in making
and setting up the sections and the photograph shows two try squares being
used to check in two planes
MAKING THE CORNER BLOCKS
The blocks are made from European Spruce
and must be profiled to fit the outline of the ribs.
Making an accurate convex profile
like this is not easy and the wood can prove difficult to hold. I have
found that a sash cramp held in the bench vice works well. An old
wooden moulding plane is the ideal tool for the job and these can often
be picked up cheaply at car boot sales or antique shops. The sole of the
plane can be re-shaped and the iron re-ground as required.
ASSEMBLING THE BLOCKS IN
THE MOULD
The blocks are fitted into the mould
and secured using steel angle brackets as can be seen in the next but one
picture taken after the bottom plate is removed.
This photograph shows the mould
assembly ready to receive the ribs. The back plate of the mould has
been cut and reassembled at a 10 degree bend using hinges since the bass
being made is a flat back which angles off near the top.
Holes have been drilled around the
edge of the top and bottom plates to take the cramps used for gluing the
ribs in place.
This photo shows the bottom plate
removed, after the ribs have been fitted, so that the brackets supporting
the blocks can be clearly seen. The inside shaping of the corner blocks
has not been completed yet, this will be done later.
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