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<DIV><FONT face=Arial size=2>Hi David,</FONT></DIV>
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<DIV><FONT face=Arial size=2>Looks like Ron N covered most of it.
Letting an appropriate number of laminations terminate to =
form the
doglegs, IMHO, is key to trouble-free vertically laminated bridge root =
lay-up.
With this approach, there is no reason to ever use less bend at a =
dogleg
than optimal. Below is a picture of my last bridge under =
clamps. I
bond my laminations together with West System epoxy. I like epoxy =
because it
takes the worry out of getting the right clamping pressure - just =
squish the
assembly together so you get the proper shape and the clamps hold it =
until the
epoxy cures - that's why I use so few clamps!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The picture below shows the basic =
clamping set-up
(epoxy has been applied).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT><IMG alt="" hspace=0
src="cid:001801c40ce7$c2d6eb20$b9b52341@youro0kwkw9jwc" =
align=baseline
border=0></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The picture below shows the raw root =
right after
coming out of clamps. The pic is zoomed onto the two doglegs at the
tenor/treble and treble/hi-treble breaks. You simply round off the =
terminated
laminations and you have your dogleg.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><IMG alt="" hspace=0
src="cid:001901c40ce7$c2d6eb20$b9b52341@youro0kwkw9jwc" =
align=baseline
border=0></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>
<DIV><FONT face=Arial size=2>These and other pictures of this =
process are
available if anyone wants to email me privately.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Terry Farrell</FONT></DIV></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial><FONT size=2></FONT></FONT></DIV>
<DIV><FONT face=Arial size=2><BR>> >I need a crash course on =
bridge
building (long bridges, bent laminated<BR>> >type). Could =
use some
suggestions on how I might go about getting<BR>> >information, =
how to
make a template, what tools I might need, materials,<BR>> =
>etc..
Whatever can be offered would be appreciated.<BR>> ><BR>> =
>David
Love<BR>> <BR>> Hi David,<BR>> <BR>> I use a rubbing =
(paper
template) from the original configuration (before I <BR>> take the =
strings
off) as a point of departure. After re-scaling, I use that <BR>> =
template
to establish the new speaking lengths, which I use to lay out the =
<BR>> new
bridge. Once you have the template for the new bridge, you need to =
<BR>>
decide how you are going to build the bridge. You can cut it out from =
solid
<BR>> stock, joined at the scale breaks to keep the grain running =
roughly
<BR>> parallel to the bridge, or you can laminate it. You can =
laminate it
<BR>> horizontally, putting the joints in each lamination in random =
places
so the <BR>> strength of the assembly won't be compromised, which =
works
fine. Or you can <BR>> laminate vertically, which means building a =
jig of
some sort for clamping <BR>> the laminations to the required curve. =
I've
done bridges with continuous <BR>> vertical laminations, but it's a =
lot
more work than should be necessary for <BR>> a one-off bridge. You =
need
laminations at 2mm or under to make the dogleg <BR>> bends at the =
struts to
maintain a semi-log speaking length progression, and <BR>> a =
tremendous
amount of clamp pressure.<BR>> <BR>> An easier way to do a =
vertically
laminated bridge root is to use the <BR>> lamination thicknesses to =
supply
the dogleg offset and not have all the <BR>> laminations continuous =
for the
length of the bridge. Terry Ferrell asked <BR>> about this a while =
back,
and it looked like a good idea to me, so I tried <BR>> it. It works =
very
well. Thanks Terry. You just have to build half a jig to <BR>> =
accommodate
it, clamping the lamination stack against it without needing a =
<BR>> caul
on the far side. Actually, I used backing strips to spread out clamp =
<BR>>
pressure, but still didn't have to cut out a full caul. Since the core =
<BR>> laminations don't have to be forced into an extreme bend, =
it's
considerably <BR>> easier to manage and takes much less clamp =
pressure. It
just takes a little <BR>> more pondering and planning before the
fact.<BR>> <BR>> That short stack of maple just above the bridge =
in the
photo is the <BR>> laminated cap (1.5mm laminations), waiting to be =
cut and
fitted to the <BR>> root. The bridge root is still rough cut here =
(hacked,
actually), and will <BR>> be smoothed and contoured before the cap =
is
installed.<BR>> <BR>> The laminations in this bridge vary from =
2mm to
maybe 5 or 6mm. I used what <BR>> I had lying around from previous =
projects
that added up to the offsets I <BR>> needed for the doglegs. It's a =
tad
over 30mm wide overall.<BR>> <BR>> To do this, you need a way to =
produce
the required laminations - be it a <BR>> table saw or band saw, and =
(ideally) thickness planer. You need lots of <BR>> clamps =
(naturally), and
scrap(able) lumber for building the jig. You also <BR>> need a glue =
that is
reasonably hard and creep resistant. I use Titebond. <BR>> =
Realistically
the glue used for laminating doesn't need to be able to hold <BR>>
continents together without shifting under billions of PSI. Gluing the =
cap
<BR>> on top, and the panel on the bottom of the root laminates =
will
effectively <BR>> insure that nothing is going to slide apart with =
a
reasonably decent glue.<BR>> <BR>> The rest is just the usual =
bridge
work - or you can send me the original <BR>> rubbing and the offset =
revisions (or?) and we can work something out.<BR></FONT><FONT =
face=Arial
size=2></FONT></DIV>
<DIV><FONT face=Arial size=2>> Ron N</FONT></DIV>
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