Restoration of a Knabe Concert Grand Page Two
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31) 
32) 
33) 
31) The plate has been removed.
32) Using the original pin block as a pattern for cutting the new pin block out of
the blank.
33) Stripping the rim of the piano. The top of the rim was scraped so that no
chance was taken of stripper getting onto the sound board which had already been
refinished.
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35) 
36) 
34) The original pin block and the rough cut new block side by side.
35) Fitting the new pin block to the plate. Care is taken to get an absolute
fit of the wood to the metal of the plate.
36) After the pin block is totally fit to the plate a very thin layer of epoxy is
coated on the mating surface and then the block is clamped tightly into the lip of the
plate. This forces epoxy into every single void that is in the lip of the plate that
it is impractical to shape the wood to fit. A layer of cling wrap is used to keep
the block from being glued to the plate. This material is thin enough and flexible
enough that a perfect shape is achieved without the plastic canting the results. It
should be noted that this is done in such a way so that the fit is still wood to metal and
very complete. The little bit of epoxy that is used takes the fit to a genuine 100%.
The layer of epoxy is very thin through most of the lip.
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38) 
39) 
37) The rim has been well sanded and now all the damaged spots that couldn't be
sanded clean are filled.
38) Setting up the drill press to duplicate the angle of the tuning pins to the
original pin block.
39) After the holes for the tuning pins have been drilled, then the plate screws are
carefully measured to determine exactly what the size of the inner part of the threads is.
Then a drill bit is selected so that the screw holes will allow the threads of the
screws the maximum amount of "bite" in the wood. The drill press is set up
on a large bench and is bolted down so that it cannot move. This enables it to be
set at any angle and keeps it from moving even the slightest amount while drilling.
This guarantees the most even sizing of holes possible over the entire pin block.
40) 
41) 
42) 
40) After the pin block has been drilled out, the registration blanks that
had been made earlier are fitted to it in order to mark out the sides and back of the
block. Then it was cut out on the table saw.
41) After the block has been cut to size, it is fitted into the case and
measurements taken and compared to the original block to ensure that the correct
orientation has been achieved. In this photo, you can see the little whips of epoxy
that were fitted to the lip to perfect the fit to the plate. Everywhere that you see
blond wood showing through, there is a direct wood to metal joint. The black
represents the thin bits of epoxy that finish the joint. In only add the epoxy to
the fit after I'm convinced the fit is good enough as it is to install into the piano with
no additional work. The addition of the epoxy is just a nicety.
42 - 43) This shows the plate before refinishing.
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44) 
45) 
44) The plate after it has received a careful washing.
45) Here the plate has received a couple coats of fresh guilding which is then
heavily sanded with very fine paper to take out as many imperfections as possible.
The larger imperfections were repaired with a filler.
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47) 
48) 
46) The plate after reguilding is complete but before the lettering is done.
47) The rim is ready for the spraying operations.
48) The rim and keybed are taped off and spraying is ready to begin. You'll
note that the inner rim is black while the outside of the case is not. Since the
sound board had already been completed earlier, before the case had been stripped and
because the condition of the original finish on the inner rim was still perfect, it was
decided to sand the inner rim heavily, then to seal it and finish over it. This was
deemed to be a better solution to stripping the inner rim. If the substrate had not
been in such perfect condition this would not have been possible.
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49) The process of spraying involves a number of steps in my process. First an
acid catalyzed filler is sprayed on. This is actually a special material that fills
the pores of the wood. This material cures chemically and is harder and more durable
than paste wood fillers and at the same time is more flexible than any other type of
catalyzed material on the market. I refuse to use catalyzed spray lacquers because
you have to build up a body of finish with them and by the time your done, the film is too
hard and inflexible to be able to expand and contract with the wood. In the case of
this catalyzed filler, it is only to fill the pores. After it has cured, it is
sanded almost completely off again, only leaving the tiniest amount of material above the
surface of the wood. Since this material is so flexible due to the large amount of
wood filler it contains, it can flex with the wood exceedingly well. The catalyst is
merely there to ensure that the material cures quickly and doesn't shrink later on causing
the pores to reappear. After this material has been sanded flat, three coats of
gloss black lacquer are applied. This is allowed to dry until it is sandable, then
it is heavily sanded so that all the tiny imperfections in the wood that were missed
earlier can be found. Most of these first three coats are removed at this stage.
Then another three coats are put down. After these three coats have had a
chance to become sandable, the entire surface is wet sanded with 400 grit paper. In
this picture, you can see the industrial rubbing machine I use at this stage to ensure a
flat surface. This is a similar machine to the one used at companies like Steinway.
Again a large portion of these three coats are removed in this process but not as
much as in the first sanding which was done with 220. By doing this wet presanding
while the lacquer is yet young, I can ensure that all of the surface area has enough
lacquer on it to prevent rub throughs. In fact, a number of areas are usually rubbed
through at this stage, especially on the edges and corners. The lacquer is still
very young and spot spraying blends in very well. Three coats of additional lacquer
are applied to any areas that rub through at this stage. Once this sanding is
complete, I have an entire piano which has an intact film of lacquer that has been sanded
at 400 grit and contains no burn throughs and also contains no imperfections. Later,
after the lacquer has completely cured, it will receive a buffing with 4/0 steel wool and
then the satin gloss will be "dressed" with 600 grit imperial paper.
50) The pin block has had all glue joints taped off and then received two coats of
lacquer. An additional coat of shellac is placed on the upper surface of the pin
block and along the lip just before the plate is dropped onto it for the last time.
This is a small nicety, but I feel it helps to bind the pin block and plate to each other
just a little bit more.
51) All the areas that the pin block will glue to in the piano are cleaned and
dressed to receive a new glue joint. You can also see where dowels were fitted into
the rim where screws had originally passed into the rim to hold the pin block in place.
These screw holes were plugged from above and through their cross section.
The screws were eliminated in the new pin block and replaced with dowel rods since the new
pin block is glued in rather than just laying in there and held with screws.
52) 
53) 
54) 
52) The plate is finished and the pin block is laid into the case and the
piano rolled under the plate.
53) Cardboard cushions are taped to the rim in strategic locations to ensure that
the plate doesn't mar the finish.
54) The plate is lowered into the piano and screwed into the rim. Also, the
pin block is screwed to the plate in a number of places. Then the plate is measured
for height and the down bearing is checked. The pin block is jacked up with the
plate after the rim screws are loosened. Then the shims that sit under the pin block
are removed and sized until they leave the plate/pin block assembly at exactly the correct
height. The plate is pressed tightly down onto the shims with clamps to while
measuring the plate height to ensure an accurate reading. Once the plate height is
correct, the assembly is jacked up just enough to free the shims one more time. Glue
is applied to the shims and they are reinserted. The assembly is then clamped down
tightly. Also, at this stage the stretcher is clamped to the pin block as well.
After the glue has cured, the plate is removed and holes are drilled along the
stretcher and into the rim at both ends to receive hard maple dowels. These dowels
reinforce the glue joints and ensure that nothing will ever come loose or shift in any
way. In this picture, you can see the holes drilled for the stretcher.
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56) 
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55) In this picture, you can see the holes drilled for dowels at the treble end of
the pin block that go down into the rim.
56) This block holds the plate in front of the pin block at the bass end.
Originally it just had a glue joint at its bottom. I reinforced this block by
refreshing this glue joint and doweling it into the rim.
57) The legs had many of their decorative features broken off. All damaged
areas and missing or weak components replaced or rebuilt. Here, some new wood
decorations are being clamped onto a leg.
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60) 
58) Dents in the wood are repaired by burning in, or with epoxy filler depending on
where they are located. Dents located on the edges are repaired with epoxy and those
on flat surfaces are burned in with lacquer.
59) While the wood of the music desk was still functional, the areas around the
glides were so badly dinged, cracked and dented, that I decided to remove the wood
altogether and replace it with multilaminated birch. The glide design was the main
reason for the poor condition of the desk so a more traditional style of glide is going to
be placed on the piano instead of the original.
60) All three legs have been finished. They don't look like much in this
picture, but they have been literally sculpted back into the correct form. Once
lacquered they should look spectacular.
61) 
62) 
61 - 62) The original keyslip was missing so a new one had to be made. Here you can see a new board being milled (61) and decorated to match the piano (62.)
