Restoration of a Mason & Hamlin Ampico for David Lucas Graves & John Herrmann
208) 
209) 
210) 
208) The spider as well as the main shaft bearings have all
been thoroughly cleaned out of all old varnish (which is actually cooked and hardened
grease), grease and dirt. The bearings were then checked for wear and repacked with
new bearing grease.
209) Now it is time to rebush the connecting arms and clean up, true up and
lubricate the spring loaded wedges.
210) The only way to keep an Ampico pump from knocking is to get the bushings very
tight. As the pump is run for the first few hours, the heat of use will iron the
felt down. If the felt doesn't start out very tight, by the time the ironing process
is complete, the bushings will be too loose and the pump will knock. The way to
judge that the bushings are tight enough is that you have to drive them onto the pins.
It isn't necessary to have to use a sledge hammer to get them on but they should be
tight enough that you can't push them onto the pins just with your fingers. To keep
the arms from being damaged during the installation, a clamp is placed over them to
reinforce the wood as the connecting arm is driven home. A few minutes later, the
clamp can be removed and no harm is done to the arm. In the case of this pump, the
arms were sadly weak. Despite my best efforts to rebush them correctly and install
them safely, one of the arms shattered because it was too weak to hold the correct tension
any longer. Fortunately, I had a spare arm hanging around the shop that I was able
to use to replace the one that broke. Normally, it should only take an hour to
rebush and restore the connecting arms and install them. These arms were so
troublesome that it took me an entire day to get it right. I could have gotten it
done faster but I would have compromised the quiet operation of the pump. I had to
keep working the arms until they were perfect so the pump would give long term, quiet and
reliable service.
211) 
212) 
213) 
211) The finished spider and arms are ready to be put
together with the rest of the pump.
212) The bellows have been assembled. I like to screw the bellows first to the
air handling manifold that connects their inner air chambers. This ensures that they
are sealing well against the manifold. Then I screw the bellows to each other and
remove the manifold as shown in this photo.
213) Now the iron plate with the drive wheel and spider has been attached to the
bellows minus the wheel. Only a couple of screws were used to start. This kept
the pump square and the spider properly aligned to the bellows. Later, after the air
manifold is solidly screwed to the bellows, I will put the rest of the iron plate screws
in and install the wheel. I can't leave the air manifold on throughout all of this
because it gets in the way of bolting the connecting arms to the bellows. It is
minor little details like the way to assemble these pumps that can only be learned over
time and that make a huge difference in the quality of the finished product. This is
an example of why amateur restorations of these types of mechanisms universally tend to
yield bad results.
214) 
215) 
216) 
214) Now that the main body of the pump is all put together,
I installed the spill plate. Note how every screw on this pump has been cleaned of
old rust and polished; then they were coated with lacquer to prevent any future corrosion.
215) The previous rebuilder neglected this next step. The cut-out manifold is
screwed onto the spill plate and then the heads of the screws are sealed with bees wax.
The nature of the pump design makes this step critical. The manifold WILL
leak air around these screws. The last guy didn't bother to seal these screws back
up. This photo shows the soldering iron and rods of bees wax that I will use to seal
up these screw heads.
216) The cut-out manifold is sealed up and the muffler box that quiets the operation
of the spill valve has been installed. Amphion originally installed these muffler
boxes with very small, hard to handle screws. I like to replace these screws with
something easier to get a screw driver onto and also longer so as to hold the box secure.
The original screws were always too short to be strong enough for the job.
217) 
218) 
219) 
217) A back view of the pump, showing the air manifold in
its final installation. Also, you can see the tubing run from the cut-out manifold
to the equalizer (or reservoir if you prefer) that we made new because the old one was
shot. In most installations, the equalizer is not attached to the pump. The
roomy space under this Mason and Hamlin allowed them to attach it to the pump.
218) The finished pump. Upon testing, this pump was extremely tight. It
is, in fact, probably tighter than it was when it left the factory. This will mean
that more air is going to be drawn through the spill while it is new. It also means
that the pump will still be giving factory original suction supply to the mechanism long
after most pumps would have needed rebuilding.
219) The final bits attached: the mounting brackets and belly cloth stand
offs.
220) 
221) 
221a) 
220) Now that the player mechanism has been restored, it is
time to turn our attention back to the piano itself. The new ribs have been shaped
so that they fit the notches in the rastin (the ledge on which the sound board is glued)
and match the widths of the original ribs as taken from the old sound board. Any
places where the original work done by the factory left the rastin fitting the ribs
improperly, repairs are made to ensure a tight fit
221) 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.
221a) A photo of the process of shaping ribs 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.
222) 
223) 
224) 
225) 
222) 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.
223) Fitting the new ribs into the notches so that they are a perfect fit and fine
tuned to align with the glue shelf (rastin) to which the sound board will eventually be
attached.
224) Gluing up the layers of the new vertically laminated bass bridge core.
Although solid wood could be used here as in the original, I feel that laminating is a
very good alternative. The cutting of the wood into thin strips like this relieves
all inner tension from the wood. The epoxy used for gluing up adds additional
strength and energy transfer capabilities that solid maple doesn't have. Finally,
the laminated version is less susceptible to problems over time; being more stable than
solid wood.
225) The long, treble bridge to this piano has one place which curves very
severely. The bend in this bridge is so severe that the maple would break before it
bent around this obstruction. Therefore, the wood is moistened and then heated and
bent around a form until it takes on the shape that will be needed as it is glued up into
its final dimensions. I use the bridge itself to hold the freshly bent strips for a
few minutes while they cool and dry. After they are dry, they will retain the bent
form. Finally, to keep them all in order and the bend in place, the entire set of
strips will be ganged together and clamped into position over night to help the bend to
settle down and even out from layer to layer.
226) 
227) 
228) 
226) Gluing the new quarter sawn hard maple cap onto the
vertically laminated bridge core.
227) The finished bridge core is ready to be glued onto the apron. The
original apron was in good shape so I decided to reuse it after doing some minor cosmetic
work to make it fresh and new looking.
228) I know this photo looks like a "plumber's nightmare" but sometimes
that's what you got to do! This is the long bridge being glued up in a custom made
jig. The jig is built to match the shape of the original bridge exactly. The
new layers of maple are vertically laminated to each other using West System Epoxy as the
glue. This is a very hard material which will conduct sound vibrations as well or
even better than the maple. After the epoxy sets up over night, the bridge will be
removed from the jig and will hold the shape of the bridge permanently.
229) 
230) 
231) 
229) The bridge core has been removed the next day and put
through the planer to dress it out smoothly on both sides. This squares the gluing
surfaces (both top and bottom) to the edges to make the cross section of the bridge
perfectly square (or perhaps I should say rectangular.) Now the bridge core of
vertically laminated maple is having quarter sawn maple which has been cut oversized and
fitted to the top of the core glued to it. The cap is made in sections that meet at
natural break points in the scale where plate struts run. The joining places are
closely fitted to each other for a very tight joint and glued not only to the bridge core
but to each other's edges as well. In addition, the entire gluing up of the cap to
the core is done on another jig which imparts the correct amount of sound board crown to
the bridge itself. When done, the bridge will naturally want to live in the shape of
the sound board crown. Since the long bridge is the most important rib in the piano,
it is good to do this for the same reasons that we pre-crown the spruce ribs. The
sound board will retain its crown longer and the tone of the piano will be better because
the entire assembly is "happier" in the piano having been shaped to fit rather
than being forced and bent as with so many other designs.
230) The finished bridge blank has had its ends cut and shaped to match the original
bridge and the cap trimmed to be flush with the core.
231) Many rebuilders would take this bridge blank and glue it to the sound board
just as it is and carry out the rest of the work after the sound board was glued into the
piano. And they are quite correct to do this. However, the reason they do this
is because they want to check the bearing levels for the strings with the assembly glued
into the piano and the plate lowered into its final place. They can then mark the
bridge for height and plane it to the correct height for the sound board and also mark the
locations for the bridge pins based upon the locations dictated by the plate. This
is a quite good way to proceed. However, I have certain beliefs about this process
that cause me to feel this work is better done outside the piano; at least by me.
First, this is a Mason and Hamlin which means that the original bridge dimensions were
certainly perfect from the factory. Any minor adjustments to down bearing that I
feel may be needed can easily be done using the original bridge and adjusting the plate
height and plate felt thicknesses. Every factory has to make sure their bridges are
the correct height or the pianos won't work properly. Even if the factory were to
make mistakes, they are always minor enough that they can be corrected by plate height,
sometimes shimming duplex bars and felt thicknesses. I am personally much better
able to plane bridges squarely, mark bridge pin locations accurately and drill and notch
bridges precisely with the bridge clamped to a bench where I can see it and get at it more
easily. Once it is in the piano it becomes very hard for me to work on with
precision so I do this work outside the piano. My first job is to measure the
thickness of the original bridge down to the nearest thousandth of an inch all along its
length. These measurements are precisely transferred to the new bridge and then the
bridge is planed down by hand on the bench until every inch of bridge matches the original
for thickness exactly. That task has just been completed in this photo.
232) 
233) 
234) 
232) The next step is to take a pattern from the original
bridge of the locations of all the bridge pins. I start with index holes which are
drilled into the bridge and help me to align the bridge pin locations and the sound board
to get everything aligned properly with the plate. Then I use a soldering iron to
burn a little hole through clear mylar which has been pinned to the bridge. These
holes become my locating marks onto the new bridge. The pattern, once made, is moved
to the new bridge and the index holes lined up. With some bridges it is necessary to
"figure out" where the index holes belong based upon several different other
measurements. The best way to index a bridge is to drill a hole through the bottom
of the sound board, through the bottom of the bridge right up through the top.
However, if this hole isn't perfectly square to the entire thing (which it seldom is) the
marks will not help much in the transition to the new bridge. For this reason, I
prefer to use my best judgement and numerous measurements all over both bridges to find
the best place to locate the pattern. The bottom index holes that align the bridge
to the sound board are easily transferred with accuracy by cutting a slice off the bottom
of the old bridge and taking it over to the new one and lining it up. With such a
thin slice, angles in the index hole will not have had a chance to telescope out and make
anything inaccurate. The most important thing to get right when doing this is the
locations treble to bass of the pattern and the length of the strings at note 88.
Most pianos have a 50mm length to their highest note. Some will go as high as 55mm
but they seldom go less than this. It is important to keep this measurement correct
or the tone of the treble can be compromised. A few millimeters discrepancy in the
bass, on the other hand, has little to no effect on tone as long as it is just in the
length of the string that the difference occurs.
233) Back to the bass bridge to finish up. 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.
234) 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.
235) 
236) 
237) 
235) 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.
236) 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.
237) 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.
238) 
239) 
240) 
238) 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!
239) 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. To make for a really nice
cosmetic look, the bridge pins I used were nickel plated. For better tone
production, these bridge pins are slightly over-sized compared to what was used
originally. And as a final nicety, I did not have to grind the tops of the bridge
pins down to get them consistent since I took great care to make them come out even
without doing this. The bridge pins are more rounded and the nickel plating is
preserved. This makes it less likely that you will get anything caught on the pins
when cleaning the inside of the piano, it ensures that the ends of the bridge pins will
not rust if the piano is asked to live in a moist environment and the final cosmetic look
is very slick.
240) Taking the blank sound board panel after it has been properly dried and fitting
it to the piano. The first step is to dry the board because the spruce shrinks when
it looses moisture. The goal is to dry the board to a place where it is unlikely to
ever be exposed to a climate more dry than the one it is currently under. By gluing
the board together and installing it into the piano while it is the size it wishes to be
under the driest potential climate, cracks become unlikely in the future no matter how dry
the owner's house becomes. Of course, this doesn't eliminate all potential for
cracking of the board. If the piano is subjected to very high humidity, the wood
will try to expand. When it is retained inside the piano after installation, there
is nowhere for the wood to go. Therefore, the wood fibers tend to crush under the
stress of excessive humidity. Later, if the piano is subjected to very dry
conditions, the crushed fibers can form a crack. Drying the board like this helps to
prevent problems but it does not make the piano invulnerable to abuse. The board is
now clamped to the top of the piano and a pencil mark will be traced onto the underside to
indicate the shape of the piano.
© Copyright 2010 {David Rodgers' Piano Rebuilding}. All Rights Reserved.