Thanks very much for sharing, Louis! These are exactly the kinds of ideas I
was hoping to get. :)
Bill
Sent from my BlackBerry smartphone from Virgin Media
-----Original Message-----
From: "Louis Aull" <aul...@comcast.net>
Sender: lute-...@cs.dartmouth.edu
Date: Fri, 18 May 2012 15:43:22
To: <lute-buil...@cs.dartmouth.edu>
Subject: [LUTE-BUILDER] Re: Scalloped Ribs
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Bill,
A lute rib tapers at each end, which means the outer fibers that would have
made it down to the fastening point on each end are cut. As a result, there
is no circular binding force to hold them down like the center fibers of the
rib have. As the wood naturally tries to straighten out of its bend, the
scallop occurs since there is nothing to stop the outer fibers from
straightening. To enhance this naturally, don't bend the rib completely to
the form, and use some force to pull the rib onto the form to complete the
curve. The edges will curl up away from the form more. To defeat this, over
bend and heat twice so the rib is over curved, and the scallop will lay flat
when forced onto the form. Cut the rib roughly to shape before bending .
Another trick is to fasten the rib at each end on the form and use a heat
gun on the outer edges of the rib. The heat will cause the bent curve on the
outer portions to relax and the rib will curl up more. All these methods
produce a mild scallop. It helps to bend all the ribs before installing them
so they are consistent and will meet up on the form. For a brutal scallop,
you would need a shaped forming iron to force the complex curve (yuk). The
thinner the rib, the more the scallop. However, get too thin and you risk
plastic deformation of the shell at the neck block, and the neck will come
forward, ruining the action.
I use aircraft silk on the back of rib joints and have never had one crack.
I can actually heat the inside of the shell before putting on the soundboard
to relax out any stress in the shell. This also enhances the scallop.
I have seen lutes (60's and 70's) where the maker made the ribs thick and
scraped the scallop out.
Louis Aull
Phone: 770.978.1872
Fax: 866.496.4294
Cell:404.932.1614
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<p class=MsoNormal>Bill,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>A lute rib tapers at each end, which means the outer fibers
that would have made it down to the fastening point on each end are cut. As a
result, there is no circular binding force to hold them down like the center
fibers
of the rib have. As the wood naturally tries to straighten out of its bend, the
scallop occurs since there is nothing to stop the outer fibers from
straightening. To enhance this naturally, don’t bend the rib completely
to the form, and use some force to pull the rib onto the form to complete the
curve.
The edges will curl up away from the form more. To defeat this, over bend and
heat twice so the rib is over curved, and the scallop will lay flat when forced
onto the form. Cut the rib roughly to shape before bending . Another trick is
to fasten the rib at each end on the form and use a heat gun on the outer edges
of the rib. The heat will cause the bent curve on the outer portions to relax
and the rib will curl up more. All these methods produce a mild scallop. It
helps to bend all the ribs before installing them so they are consistent and
will meet up on the form. For a brutal scallop, you would need a shaped forming
iron to force the complex curve (yuk). The thinner the rib, the more the
scallop. However, get too thin and you risk plastic deformation of the shell at
the neck block, and the neck will come forward, ruining the
action.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I use aircraft silk on the back of rib joints and have never
had one crack. I can actually heat the inside of the shell before putting on
the soundboard to relax out any stress in the shell. This also enhances the
scallop.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I have seen lutes (60’s and 70’s) where the
maker made the ribs thick and scraped the scallop out.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Louis
Aull<o:p></o:p></span></p>
<p class=MsoNormal><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Phone:
770.978.1872</span><o:p></o:p></p>
<p class=MsoNormal><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Fax:
866.496.4294<o:p></o:p></span></p>
<p class=MsoNormal><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Cell:404.932.1614
</span><o:p></o:p></p>
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