Restoration of a Clavia-Concerto for Steven Baskin
30a) 
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30a) Now the long bridge is placed over the fitted ribs and
set so that it is exactly in the position it will occupy after reassembly. Then
marks are made directly on the ribs to show where the long bridge will pass over them.
I will then shape the ribs so that they have the proper crown built right into
them. I set this crown in such a way that the highest point on each rib is as close
to being directly under the long bridge as possible. My jig that is used for shaping
the crown on the ribs has an indicator mark that shows me where to align my marks on the
ribs so that the jig will shape them accordingly. Then the ribs are shaped so that
they will be crowned and also set to be highest directly under the long bridge. A
router is used to cut this shape into the ribs.
31) A photo of the precrowned ribs, showing how they have the proper crown cut into
them. Most rebuilders and even factories skip this step and force the crown into the
board during the glue up process. This makes the board less reliable, less long
lasting and reduces the quality of the sound. My way of making the ribs causes the
board to be much better sounding and more long lasting.
32) After the ribs have been crowned, I clamp them to the old sound board and trace
the shapes of the original ribs onto the new ribs. Then the shape is rough cut on
the band saw and fine tuned at the sanding station. After that, I set the ribs back
into the piano and fine tune their fit by hand until they are perfectly flush in their fit
into the notches.
33) Gluing the first parts of the new bass bridge together. The first
stage was to glue up the core of the bridge. For this, I used a technique known as
vertical lamination. Strips of flat sawn maple are glued up into the shape of the
bridge. By using flat sawn maple for these strips, once glued, the quarter sawn
dimension of the maple is set between the strings and the sound board. Maple
transmits vibrations along its quartered grain better than it does the other direction.
The strips are favored because they transmit the vibrations of the strings along
the length of the bridge better than solid wood can do. In this bridge (which is
straight) solid wood could have been used with success. However, the laminated wood
will also be better because of the mix of West System epoxy used to glue it up and the
laminated effect making the entire assembly harder, a better vibrator and more stable.
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36) 
34) A special jig that I use for making vertically laminated
bridges is called into service. The jig is cut out to the exact bridge curve of the
piano I'm currently working on. The form is lined with thin plastic to keep the new
bridge from gluing itself to the jig and then the layers of vertical grain maple are
coated with West System epoxy and placed into the jig. Then the entire assembly is
carefully clamped down until it is under tremendous pressure. Once the epoxy has
completely cured, the new bridge core can be removed and will hold its shape exactly as
set up in the jig with no springing back whatsoever. After this, I will glue the jig
back together again so that I can cut a new shape out of it for the next bridge.
Occasionally, I make an entirely new jig when the old one has been cut out and glued back
together too many times.
35) The quarter sawn hard maple cap has been cut out and is ready to be glued to the
treble bridge core which is vertically laminated. Now that the core is out of the
press and is the same shape as the original bridge, it must be glued to the cap on another
jig which will impart the appropriate amount of crown to the long bridge. Just as we
went to great lengths to pre-crown all the ribs, the long bridge must also have its crown
built into it. This will make the entire sound board assembly more strong and
durable. It will also increase the power of the tone of the piano. Most
rebuilders do not take this step into their own work. They glue up the long bridge
totally straight and bend it to the sound board later. I believe this adds undue
stress to the glue joint between the bridge and the soft spruce of the sound board.
Far better to create the crown by using the maple to maple joint of the cap to core.
The long bridge has its new cap glued into place with West System epoxy. I
like the epoxy for its acoustic properties but I also like the fact that it is totally
impervious to moisture. These glue joints that I am making in this bridge will be
forever. No amount of moisture exposure can ever cause them to come apart.
Other joints that must be reversed in the future (such as the joint gluing the sound board
to the piano itself) will be done with acoustic glues that are effected by moisture.
This way the sound board can be replaced again in the future with little harm to the joint
with the piano.
36) Gluing the quarter sawn maple cap to the top of the bass bridge core.
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38) 
39) 
37) The treble bridge has its new cap in place and all glue
squeeze out has been removed. In addition, the original bridge was carefully
measured for thickness and the new bridge matched to the original right down to the exact
thousandth of an inch. It is also appropriate to leave these bridges with their caps
blank and too high and glue the sound board up with the bridge in this unfinished
condition. After the entire assembly is glued into the piano, the details of the
bridge top are marked out, the height of the bridge planed down by hand and the work of
drilling and notching done inside the piano. This is a fine way to proceed, however,
if you use great care with your measurements, it is possible to produce an excellent
result outside the piano. I, personally, feel I do a better job of drilling the
bridge and I know I do a better job of thicknessing the bridge with it out of the piano
where I can get better power tools on it.
38) The finished bass bridge core is ready to be glued to the apron. The
original apron was made well and still in excellent condition. I dressed it up some
to remove cosmetic inconsistencies and will reuse it with this new bridge core.
39) These two photos show the bass bridge after it was completed. The first
photo shows the bridge after the pin holes had been drilled, the top lubricated and the
edges chamfered. The second photo shows all the bridges I am currently working on
after they were finished and the sealant coat put on them.
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40) Here, you see the long bridge has had its pin holes predrilled. A special
collar is custom made to fit over the drill bit. The collar is made from wood that
is slightly softer than maple to prevent it marking the wood at the top of the bridges.
Still, it does leave a slight mark that actually goes away after burnishing,
notching and pinning. The reason for this wooden collar is to prevent the drill
itself from making contact with the bridge. Of course, I could just stop the
drilling before the drill hits the bridge. However, I want the holes precisely the
same depth each. I want them a specific depth which permits me to drive the bridge
pins all the way into the bottoms of the holes. The tips of the bridge pins will
seat into the maple and make better sound transmission. Also, with the holes all the
same depth, I can get the bridge pins to the same average height across the bridge for a
nice cosmetic result. The normal way to do this job is to drill the holes too deep,
drive the pins in on the shallow side and then grind them all to the same height with a
file or belt sander. This gives a good cosmetic result but compromises tone a
little. This way of drilling enables me to not have to grind the tops of the pins at
all. This makes for a better tonal result at the same time it produces a very
special cosmetic result.
41) The top of the long bridge has received four coats of McLube. This is a
special lubricant which can be burnished to a nice, soft gloss and makes the top of the
bridge very smooth and even slippery for better tuning stability and a good cosmetic
result.
42) The next job is to notch the top of the bridge so that the strings will clear
the bridge on their way to meeting the bridge pins and also to ensure that the strings hit
the wood of the bridge in the same plane as they hit the bridge pins. This prevents
false beats and increases sustain. The first task in notching out the excess wood is
to carefully cut saw kerfs into the wood down to a pre-marked depth. The mark is
made on the sides of the bridge and the saw cuts are made just to the line. When the
chisel removes the excess wood, the saw kerf will keep the bridge from splitting in places
we don't want removed. A round razor cutter is then driven into the saw kerf to
cause it to take a rounded shape near the pin holes. This will be the shape the
chisel will make so it further prevents splitting.
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43) The bass bridge has received its new bridge pins. After it is glued to the
piano, a final coat of lacquer will finish dressing up the appearance. Because this
shot was over-exposed, I had to wash it a number of times through software to get it
looking better. This magnified some areas of the wood which have been sanded; making
them look uneven. They aren't uneven and will be even better yet once they've
received a coat of lacquer.
44) Now I carefully notch out the long bridge to match the original. To do
this job right, requires a chisel which is razor sharp. It is necessary, actually,
to resharpen my chisels about three times for each bridge. I use the curved shaped
knife to help me get a clean curved shaped cut. To sharpen these tools, I use a
diamond stone and a special jig. After rough sharpening them on a course stone, I
fine tune them on a very fine stone. Each side of the chisel's cutting edge is
sharpened on the stone until a fine wire edge is drawn up on the opposite side. Then
the chisel is flipped and the other side worked until the wire edge comes up on the
opposite side. Then the chisel is buffed on the polishing wheel to clean off the
excess metal on the edge and point the sharp wire edge toward the cutting direction.
This process is repeated, as I said, three times for each bridge. I wear a
very clean glove on one hand as I work to keep my hand oils from soiling the freshly cut
wood and to protect my hand from the nice clean edge I've created on the corners of the
bridge. After the notches are all cut, I will seal the notched areas with an epoxy
sealer which forms a beautiful finish with just one coat. The rest of the bridge
will be finished solely with lacquer. Then the bridge pins will be driven into place
and the bridge will be ready to glue to the new sound board. A basic cut out is all
that is needed to make the bridge function well. The real important part is that the
notch begin its path down exactly in the center of the bridge pins. This prevents
false beats. Many companies do not give much attention to getting the notches
looking extremely neat and uniform. They just knock off the edges any way that is
convenient and leave it go at that. Even this piano did not have perfectly uniform
notches across the length of the bridge. I give great care to making each notch
resemble all its neighbors as closely as I possibly can. The finished bridge will be
neater looking cosmetically than the original bridge was!
45) Now all the notching is complete. The final shaping of the bridge has also
been completed. This shaping includes the tapering of the bass of the bridge to
match the original. The purpose of tapering the bridge is to make the surface which
glues to the sound board straighter than the bridge is on its own. The sharp bends
are taken out. Also, the treble area is thinned to leave more sound board area free
from being glued to a bridge so that more spruce will be available for free amplification.
This also gets the edges of the treble part of the bridge farther away from the
rastin to keep the bridge from becoming too rigid. Much rigidity in the upper treble
is desirable but too much will reduce the sustain and power of that section. The
accompanying photo here is of all the bridges I've built in the time I've been working on
the bridges for this piano. I have five pieces I was working on at the same time and
all their bridges are now made new and pictured here.
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46) The sound board has finished drying in my special hot
box and has now been worked until it fits as snugly into the case of the piano as
possible. The more tightly the sound board is made to fit, the better the tone
production and longevity of the assembly.
47) Aligning the old board with the new one via the index marks I've just made.
The various landmarks of the old board can, then, be transferred to the new one
very accurately.
48) Now the new board is marked along its edge for the diaphramizing process.
This thinning process makes the sound board more flexible along its edges. The
first step in this thinning process is to mark the edge of the board appropriately as a
guide. Then a fine toothed saw is used to make angled cuts into the board.
They go down to the mark on the edges and taper off to nothing at about six inches.
The goal is to line the thinning up with the places where the ribs thin out as well.
All edges of the board are thinned except those near the upper section of the
treble bridge. This area requires the board to be thicker for better tone
production.
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49) The first step is to use a block plane to remove the
bulk of the wood down to the marks. Then a smoothing plane is used to clean up the
marks left behind by the block plane. Finally, a sander is used to do the final
cleaning up and smoothing.
50) Gluing the bridges to the sound board.
51) Another angle of the same thing.
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52) The glued up board ready for finish work.
53) Here, the ribs have been rounded off and smoothed.
54) In this photo, we are locating the perfect spot for the bridges using the case,
sound board and plate along with strings and measuring tools.
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55) The finished sound board is ready to be glued into the
piano. Right around this time I got very sick for a while and was not always
remembering to take all the pictures I would like. Forgive me if anything is missing
which should have been shown. In this case, I plumb forgot to take a photo of the
glue up when the sound board was installed into the piano. I also forgot to
photograph the taping of glue joints and finishing of the board.
56) A shot of the piano from the back after the new sound board had been glued into
place. There is something special about how a piano starts to look after the new
board goes in. They really start to take on the look of newness that is so
rewarding.
57) The plate shown before reguilding and restoration.
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58) Occasionally, my camera produces a fuzzy image that
can't be detected until the photos are down loaded into the computer. By that time,
it is too late to take the photo over again. Sorry for the fuzzy image. This
shows the reguilded plate with the case behind it. The case has already been
relacquered and is drying in preparation for polishing.
59) Using the plates pin block, nose bolts and some clamps, I am setting the height
that the plate needs to be set at. This height can be changed at the nose bolts, by
the thickness of the wood mounting strip at the base of the plate and by the thickness of
felt used on the plate.
60) The plate height is now set and the process of stringing is soon to come.
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61) Another angle to show the plate and relacquered case
before I start stringing.
62) The final height of the stringing is set by the felt which has now been cut and
glued to the plate.
63) Setting up for stringing.
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64) This piano uses wood plate bushings to bind the pin
block, plate, tuning pins and strings into one solid mass. The bag in this photo
shows these bushings that will be installed.
65) The plate bushings are now installed into the plate.
66) The original stringing was fairly well thought out but was done a bit on
"the cheap" by the factory. They left out all the half sizes of wire to
prevent the need of buying more sizes of wire. I reworked the scale somewhat to
improve certain tonal problems that are typical of this sort of piano. All the new
treble wire has been installed. Next, I will be making a paper pattern to send to
the string winder for manufacturing of the bass strings.
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