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Hi all,
I've just come through a couple of busy months.=20
The last couple weeks I've put in over 80 hours=20
on tools per week, to get the Yamaha CF rebuild=20
out the door for its first concert tomorrow.=20
Before that, we've been building a new piano out=20
of a Kawai KG5 case and plate, a commission from=20
pianist Gerard Willems, the concert pianist who=20
recorded the Beethoven piano works on the Stuart=20
piano. The Overs-Kawai is for his home studio. We=20
are prepared to build further examples of the=20
Overs-Kawai 200 for FOB A$60,000 (plus 10% GST=20
for local buyers).
I'm pleased with the outcome of this design=20
exercise, as I wanted to create a piano with a=20
long-ish sustain and a smaller dynamic range, to=20
produce an instrument more suited to a smaller=20
studio. I believe the power of our 225 piano is=20
way too much for a small studio. I also wanted to=20
produce a studio instrument with a more=20
economical finish than the standard high gloss=20
finish. After experimenting with a number of=20
colour mixes I arrived at a dark green (somewhat=20
darker than British racing green). A semi-gloss=20
two pack polyurethane in the green was sprayed=20
off the gun.
The new 200 cm piano also features an Overs=20
action, two new struts from the plate to the=20
belly rail (originally there were none), a large=20
sound board cut-off and an I rib board. There is=20
no treble cut-off in this piano since it=20
originally had a relatively small sound board=20
area out behind the bridge in the top treble=20
bridge section. The bridges and scale are a new=20
design, with a nominal bridge height of 34 mm and=20
a width of 35 mm. All bridge caps are=20
multi-laminated maple veneer glued up with West=20
System.
Images can now be found at;
http://members.optusnet.com.au/ronovers/overskawai1.jpg
The sound board is made from solid sitka spruce=20
and is fully rib crowned and supported. It is=20
darker in colour because we haven't bleached it.=20
The bass corner cutt-off is made from a=20
hardwood-ply laminated sheet which has a softer=20
rock maple veneer top and bottom. The inside=20
surface of the outer rim was originally black,=20
but the veneer underneath was undamaged and with=20
quite a nice figure, so we stained it and=20
finished it with acid cat lacquer at the same=20
time as we sprayed the board top and bridges. One=20
of the nice things I like about grands where the=20
pin block is removable, is that you can respray=20
the inner rim, sound board and action bay with a=20
clear finish coating in the one operation. This=20
approach allows us to avoid the typical=20
'straw-broom-finish' which pervades most action=20
bays. I remain unconvinced of the alleged=20
superior tuning stability of those designs in=20
which the pin block and stretcher rail is built=20
integral with the case. I really like the Kawai=20
KG6 as a shell from which to build a decent small=20
grand (especially the earlier examples with the=20
oak rims and back beams). I believe these=20
instruments, when rebuilt appropriately, will=20
outclass a new S&S model B.
http://members.optusnet.com.au/ronovers/overskawai2.jpg
This image shows the treble string sections.=20
There are no specific front duplex lengths in=20
this design. Any noisy duplex segments get a=20
couple of drops of glue along the duplex segment=20
to detune the noise. The typical Kawai=20
half-round-chromed rear stringing pillow has been=20
substituted with a hardwood antarctic beech=20
strip, which is profiled in thickness to achieve=20
the desired downbearing settings (I prefer to set=20
the downbearing by varying the stringing pillow=20
height instead of varying the bridge height -=20
this is because I want a certain bridge stiffness=20
to avoid tonal 'dips' between the sound board=20
ribs). The stringing pillows are covered with=20
green felt to slightly dampen the back scale=20
activity, without the need of a listing strip.=20
The serial no. first section, "OK1", represents=20
Overs-Kawai s/n 1, while the 662460 is the serial=20
number of the original shell.
http://members.optusnet.com.au/ronovers/overskawai3.jpg
This image from the bent side shows the green=20
outer finish a little lighter than it is. The=20
camera flash washed the foreground a bit. The=20
plate is close to original with the exception=20
that the strut junction at the bass/treble break=20
is re-profiled to improve its aesthetics, and the=20
plate perimeter bolts and set bolts are all=20
chromed dome nuts, similar to the Overs 225=20
pianos, with a Baldwin style plate mounting=20
system. The capo bars received their usual=20
re-profiling and hardening. Also notice that the=20
strut between the agraffe and first capo section=20
has been ground to allow bridge clearance. The=20
higher 34 mm bridge, combined with the much=20
smaller crown radius causes the bridges to sit=20
much higher in the piano, particularly in the mid=20
sections. The stringing pillow heights in the=20
tenor sections are often as high as 10 mm.=20
Ideally, a crown in the treble hitch plate would=20
help the setup where high-crowned replacement=20
sound boards are fitted. The original crown in=20
the belly rail is removed, prior to fitting the=20
sound board cutoff, to slightly reduce the final=20
bridge height in the middle.
http://members.optusnet.com.au/ronovers/overskawai4.jpg
This image shows the new bass bridge design. The=20
suspended bridge is now thankfully gone, and the=20
speaking length of A1 is shortened by 20 mm to=20
allow for a longer back scale. Similarly, the=20
hitch pins for the singles have been moved back=20
so that A1's hitch is as close as possible to the=20
back of the plate. The original piano had an A1=20
free-backscale-segment length of only 85 mm. This=20
new configuration yields a free length of 135 mm=20
at A1. With the double looped german eyes, this=20
piano is now producing a very acceptable low bass=20
for a 200 cm piano. The bass cut-off can be seen=20
meeting with the bass side about a foot (300 mm)=20
back from the hinge cut-out. The darker wood=20
moulding between the sound board and cut-off area=20
is antarctic beech. The plate is fitted using the=20
Baldwin style mounting system, so the visible=20
hole in plate perimeter-flange is for accessing=20
the plate height adjustment screw, prior to=20
fitting the perimeter bolts.
http://members.optusnet.com.au/ronovers/overskawai5.jpg
Well that's it for the this piano for now. The=20
lid and fall has to be sprayed with top coat yet.=20
Should be all completed in a couple of weeks.
The Yamaha CF which we rebuilt for Dubbo Council=20
went out on Tuesday. The sound board re-crowning=20
was very successful. This piano now has lots of=20
sound board crown and it sunk out no more than a=20
standard new sound board during the stringing=20
process. The re-whatevered instrument seems to=20
have lost its characteristic=20
Yamaha-CF-light-tone, with the modified board=20
yielding a much darker tone. While the plate was=20
re-installed into the case to the same height as=20
original, the cast stringing pillows had to be=20
packed up by around 5 mm to achieve the desired=20
down bearing settings. This indicates that the=20
crown of the restored board was considerably=20
higher than when the piano was new. Notably, the=20
tone in the killer octave area was most=20
satisfactory. We used new CF3 hammers for this=20
repair and I must say I'm totally struck on the=20
quality of the Wurzen felt. Thank you Andr=E9 for=20
bringing this hammer felt to our attention. The=20
tonal balance over the compass of the piano was=20
quite remarkably even, even before any voicing=20
was undertaken. I've taken images of the=20
re-crowning process, but they were taken with my=20
conventional SLR camera. The Overs-Kawai images=20
are the first digital images we've taken. I may=20
post a report to the list regarding the=20
re-crowning process once I get the images=20
scanned. I predict that a lot more re-crowning=20
jobs will be undertaken in instances where the=20
panel is not split.
Ron O.
--
OVERS PIANOS - SYDNEY
Grand Piano Manufacturers
_______________________
Web http://overspianos.com.au
mailto:ron@overspianos.com.au
_______________________
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