Hello Sterling!!
Its been a long time posting for me, I have been pretty busy with work...
I offer what I have done in the past.
Many of the EXCELLENT builders who post here will no doubt have
wonderful input to give you , no doubt..
For my part, having replaced a number of bridges in restoration work as
well as gluing on bridges in new construction, I would say
It is much better to remove the top. MUCH BETTER in fact
Your description is good by the way, and certainly justifies replacing
the bridge.
Also since the current bridge is not to be kept, you do have a great
advantage here.
However there are issues .
Removing a well glued on bridge is no easy task. Heat and moisture are
required and the application of these forces can easily damage a top
beyond repair...
After you remove the top from the bowl , you must focus the heat and
moisture very carefully, and take extreme caution not to be impatient
and lift up the bridge with any force as this could create tear outs in
the top underneath. This situation is a nightmare to deal with , but CAN
be addressed if the damage is shallow.
Given that you are going to make a new bridge, I suggest that you begin
by removing whatever top detail has been placed on the top of the old
bridge ( if any) and then to CAREFULLY plane down the old bridge with a
block plane to where the remaining bridge is perhaps 1.5 mills thick or
less if you can ...
Now you can place hot water on a rag cut to fit EXACTLY on top of the
remaining bridge with a LITTLE overlap and then cover the cloth with
tin foil or saran wrap to prevent the water from evaporating. Please
leave this in place for a while .
As thin as the remainder of the bridge now is, the water and heat
should penetrate fairly well into the top and glue joint underneath, and
begin to loosen the bond.
Now under one of the ears see if you can't slip a single edged razor
blade between the bottom of the bridge and the top... You must not force
this .... if there is any resistance you should stop immediately!
You will need to apply more heat and moisture using hot water and a
SMALL iron directly on the top of the remainder of the bridge on the
area where you wish to start, and try again... I stress that it is
important to be careful to control how much heat and moisture is
absorbed in the top and most importantly to keep this in area as close
to the perimeter of the bridge as possible..
If you have removed the top, of course you can apply moisture and heat
from UNDERNEATH the top just below bridge, and be very effective as the
top itself is more porous than the ebony.
Carefully move the razor blade along the joint until the bridge
remainder lifts up completely along its length....
At this point I recommend damping the top at least around the area where
there has been heat with cold water and prefer myself , to damp the
entire top - top and bottom to equalize the tensions so as to to help
avoid selective shrinking of the top and the ensuing warps that will
incur as a result. If you do damp the entire top , AVOID the ROSE TOP
AND BOTTOM !!!!!!!!!!!!!!!!
Just after the top has been damped, I then place the top (topside down
) in a go bar box ( you must use some cellotape on the go bar box
bottom where the bridge area is going to be , so that the remaining glue
in the bridge area of the top doesn't bond it to the box) and then
using cellotaped bars of your manufacture (say 1/2 x 1 x 12 inches or
so) go bar clamp these bars down across where the bridge was located to
ensure that the top is flat in this critical area. Also brace the
existing lateral braces of the top by placing go bars in the center of
each of these lateral braces and at each end , and put go bars on the J
bar as well as the treble bars.... I recommend leaving it like this for
several days until the top has stabilized, is flat, and all moisture
you have put into the top is gone.
Now comes an interesting thing......
The new bridge should actually be glued on with the top with the same
humidity as when all the braces were glued down in the first place.
This is to prevent stresses from being introduced into the top which
will will deaden the sound.
Since we have most likely no record of what this humidity figure was ,
we now have a bit of a mystery !~!!!
In one lute I worked on and which needed a complete bridge re gluing -
the bridge was lifting up under the ears and also under the first course
but was otherwise perfect, my client wanted to reuse the original bridge.
This instrument by the way was made by a well known and well respected
American luthier.
As such, I faced this problem of not knowing the relative humidity used
during the gluing of the braces
I discovered that keeping the top in a go bar box at 44 percent humidity
to start with, the top developed a bow with the center of the top
depressed relative to the edges, and this within less than 20 minutes
from removing the go bars, and this in a room with a relative humidity
of around 55 percent! This indicates to me that the top was in fact
braced at a higher humidity.
I slowly raised the humidity in the box 5 percent at a time, with a
good deal of time used to stabilize the top at each setting and this
over the next week or two.
I discovered that only around 55 to 60 percent humidity in the go bar
box, did the top hold its flatness fairly well after removal ......
WEIRD!!!!!
I later learned from one of our best lute players here on the west coast
that this particular builder (who he knew) built his instruments in a
dampish basement and didn't use a humidity controlled go bar box to
brace his tops.......
Well anyway (and having no choice) I glued the bridge back at 55% .
The instrument sounded great thereafter, our builder did do an admirable
job.
This hopefully will give you some idea at least of my process in this
kind of repair...
best
Richard Lees
On 6/14/2012 9:27 PM, sterling price wrote:
Hi-I'm not sure if this list is still active so here goes---I have a
small archlute with a bridge that is made of ebony and I would like to
replace it with something more appropriate. Also because the string
spacing and action is all wrong. My question is--what is involved in
removing a bridge and replacing it without removing the soundboard? I
just need some advice on how to proceed, or if I should leave it alone.
--Sterling
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