Restoration of a Bush & Lane/Welte for Kim Davis
37) 
38) 
39) 
37) Recovering the pneumatics. The hinge ends have to
wait for the glue to set up before being glued down.
38) The pneumatics are trimmed along the first three edges, then they are closed and
the hinge ends glued down and trimmed. The pneumatics are weighted to keep them
closed until the hinge end glue can dry completely. If this step were skipped, the
cloth on the hinge ends would constantly try to keep the pneumatic open. This is
called being "hinge bound." By using this method of gluing, the pneumatics
become very flexible and open and close with the slightest variation in air pressure.
39) Gluing heavy paper gaskets to the glue joints of the pneumatics. This step
will help to preserve the pneumatics and the trunks they are glued to in the next
restoration cycle. I had a good deal of trouble getting the pneumatics off the
trunks and did break a few in the process, which had to be replaced. This design of
mechanism uses a fixed board for the pneumatic which is very thin; far too thin, in my
opinion. These paper gaskets will not interfere with the glue joint during the life
of the pneumatic but will make future disassembly vastly easier and safer. These
mechanisms are increasingly rare and we must make every effort to preserve them.
This includes looking ahead to future restorations and seeking ways to make those go more
smoothly. There are only so many times that a mechanism can be rebuilt before the
wood surfaces are sanded down to the point where they will require the application of new
layers of wood and/or the construction of new components. Simple steps like this
help to forestall the need for extreme techniques needing to be employed to restore the
mechanism in the future. I want this piano to still be restorable in 200 years.
If each restoration is done as carefully and as thoughtfully as this one was, that
will be possible.
40) 
41) 
42) 
40) This is slightly out of order. This shows a pneumatic being tested to
ensure that it is 100% air tight before the gaskets are glued into place or the pneumatic
is glued to the stack. Once they are glued to the stack, it is nearly impossible to
test individual pneumatics for air-tightness.
41) Gluing the pneumatics back onto the trunks. Hide glue is used because it
is the most easily reversible in the future. It is also historically correct to use
hide glue because the Auto Pneumatic Action Company that built it used the same thing.
42) Cleaning the poppet wires and replacing the leather nuts and felt washers.
It was unnecessary to rebush the guide rails on this restoration cycle. The
tops of the poppets were also lubricated.
43) 
44) 
45) 
43) The three tiers after the pneumatics had been glued back into place.
44) Reattaching the lifter fingers that help to connect the motion of the pneumatics
to the piano's keys. Each one is "glued" to the pneumatic with burnt
shellac and reinforced with two screws. The screws do most of the holding. The
shellac helps eliminate the loosening of the screws from vibration. Shellac is used
instead of hide glue because it sticks to metal better. Also, the three tiers have
been put back together.
45) Replacing the leather gasket that seals the three tiers of pneumatics to the
valve board. The original leather was still sealing very well. However, it was
starting to rot along the outer edges so I replaced it.
46) 
47) 
48) 
46) Reattaching the poppet assembly and installing the
bottom batch of leather nuts that hold everything together. The three tiers have
also been reassembled.
47) Testing the stack after the valve boards have been screwed back into place.
Each half of the stack was so air tight that no air could be sucked out of it when
all the signal nipples were blocked as shown in this photo. Next, each note was
tested to see that it repeated quickly and quietly with the correct amount of energy
imparted to each pneumatic.
48) Now that the stack is restored, it is time to concentrate on the expression
mechanisms. This is the expression assembly before work began.
49) 
50) 
51) 
49) The control valve box after it was removed from the main
assembly but before it was taken apart.
50) The expression control pneumatics before work began on them but with the
expression valve box removed.
51) The expression valve box has now been taken apart most of the way.
52) 
53) 
54) 
52) Now the box is clear apart and all the old leather
gaskets and pouch leather has been removed. The original leather was still good
enough to make the unit work. Even though the pouch leather was still strong, I
could not get it to seal 100% no matter how many coats of sealant I applied.
Therefore, I took out all the pouches for replacement. Most of the valve leathers
were still perfect. I only replaced the outside primary valve face to the pedal
control valve. It was the only leather facing that had gone bad. Because of
the new gaskets, all the valves had to be readjusted, however. While the pouches
were out, I took the opportunity to seal all the pouch wells with fresh sealant.
53) The pouches have been replaced and are now being sealed with rubber cement.
The circles at the centers of all the pouches are masking tape. This keeps
the sealant from penetrating the pouch in that area. Lifter blocks get glued to the
pouches in these areas and the leather needs to be kept clean so that the glue will stick
to it.
54) The pouches are now finished and the lifter blocks are glued into place.
We are now ready to start putting the device back together. It will then be
regulated and tested.
55) 
56) 
57) 
55) Reassembling the valve assembly and adjusting the valve
travel.
56) The entire assembly is back together and ready to be tested.
57) Testing the valve box. This is a most important step. Even though
great care was taken in every aspect of the rebuild, I still came across three valves that
didn't operate perfectly. This is a very delicately balanced mechanism. The
slightest misadjustment will cause it to not work. It required that I take much of
it apart to correct some of the problems. In the end, it worked perfectly.
58) 
59) 
60) 
58) These are the actual expression pneumatics that are
controlled by the valve box that was just completed. They are all attached to a
wooden rail. In this photo, they have been removed from the rail and marked so that
they don't get mixed up. There are two of each and they must not get swapped with
their counterparts when they are put back together.
59) This is the wind governor that feeds suction to the expression valve box shown
earlier. It has been taken apart and is ready to be rebuilt. The only thing
not showing in the photo is the actual valve that controls the wind inside the pneumatic.
That valve hadn't been removed from the pneumatic when this photo was taken.
60) The damper and hammer lift rail control pneumatics before they were rebuilt.
61) 
62) 
63) 
61) The wind governor to the expression valve box is now
totally restored and working perfectly. One important aspect of the Welte design
regards perfect air tight construction. Every component needs to be rebuilt in such
a way that it is absolutely air tight or the expression system will not work. Other
designs allow for a more sloppy restoration. This system will not. It either
has to be perfect or it won't work.
62) The damper and hammer lift rail pneumatics are rebuilt and perfectly air tight.
63) These two pneumatics are called the modulators. They are not activated by
the roll. You activate these from a switch in the drawer. Their function is to
effect the expression system in such a way that it will not get loud. All the
expression will still continue in the music but the loud portions are toned down by the
activation of these two pneumatics. Again, these must be totally air tight or the
expression of the system will suffer.
64) 
65) 
66) 
64) The modulators are now rebuilt. You can see that
there is knotted tubing over the inlet nipples. The pneumatics are shown in a closed
position. The pneumatic cloth (especially when new) has a tendency to want to drive
pneumatics of this size and shape open. That opening force is canceled out by the
knotted tubing. This picture was taken in this way to show how air tight these
pneumatics are. They are so tight that they will not open as long as the signal tube
is blocked. No leaks of air are available to allow them to do so.
65) These are the expression governors. These pneumatics are probably the most
difficult pneumatics to recover of all devices out there. If they are not perfectly
air tight, they won't work. If they aren't perfectly flexible, they won't work.
And the design is such that they are very difficult to get air tight. This
photo was taken before restoration began.
66) This photo shows one of the expression governors partially taken apart. It
shows the fortzando valve sitting on top of the pneumatic. This valve was originally
made with a pouch of pneumatic cloth. The problem with using pneumatic cloth is that
it is not as flexible as leather. These valves would have a tendency to operate
somewhat badly with pneumatic cloth as the moving material. I intend to correct this
by replacing the cloth with well sealed leather. The reason that they used cloth
here was two-fold. The size of the pouch was large enough that they felt that it
would be able to flex properly despite the use of cloth. Second, the valve that
operates this pouch is a lock and cancel. If the pouch isn't perfectly air tight,
the valve will refuse to lock. Because I'm replacing this less flexible material
with leather, I will have to take great pains to make sure it is very air tight. In
fact, even with an air tight pouch, and a carefully sealed internal air chamber, these
valves have a tendency to be a bit leaky.
67) 
68) 
69) 
67) The expression governor pneumatic has been taken apart,
cleaned up and repainted. Also, the internal air chambers have been sealed and the
leather gaskets replaced. The old gaskets weren't that bad. However, this
pneumatic MUST be perfectly air tight or it will not work. For the sake of
completeness, anything that wasn't in the same condition it was in when it was brand new
got replaced. You can see in the upper right that the fortzando valve has been
restored using pouch leather in place of the pneumatic cloth. This is a much more
difficult and expensive way to build this valve but I feel it will operate more quickly
and quietly this way.
68) All the components to this device have been rebuilt and are now ready to be put
back together. It takes two separate hinges, four separate pieces of pneumatic cloth
and two punchings of sealed pouch leather to get these air tight. If every part
isn't aligned perfectly and installed with extreme precision, the unit will not work.
When finished, the movable board was extremely free floating in its motion and the
unit was absolutely air tight. The biggest trouble spot on these was the internal
knife valve that actually governs the air to the pneumatic stack. These valves are
not made in a sturdy way and have a tendency to warp. It took a lot of sanding and
other special techniques to get these to seal properly.
69) The completed expression governor.
70) 
71) 
72) 
70) Both expression governors are now restored.
71) These are the expression pneumatics before restoration. The function of
these pneumatics is to open and close the slide valve that is located inside of the
expression governors. At this stage in the process, I have shown all of the unique
aspects of these mechanisms. I will, therefore, save a little disc space by not
showing a lot of details of the restoration of these pneumatics.
72) The expression pneumatics have been totally rebuilt (including new valve leather
and pouches) and the entire expression system has been reassembled. The photo shows
the damper and hammer lift rail pneumatics as well. These are part of the expression
system but are attached to the piano separately from the main expression assembly.
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