From Ron Overs <sec@overspianos.com.au>
David,
>Why do manufacturers harden capo bars rather than cast (or grind)
>the underside of the strut flat, rout out a groove to receive a
>steel rod of proper radius, shape and hardness and insert it there
>where it could, when it's worn, be easily changed and where the
>consistency would be more easily controlled. Is there a compelling
>reason not to do it that way?
Yes, this is a way to build a capo' with a controlled profile and a
hardened surface. When the first Yamaha grands came out in the late
70's with the V-pro plates, they used a bar under the capo just as
you've described. I seem to remember from their literature at the
time that they mentioned a hardness of C60 for the bar. Piano wire is
typically about C45, and a mild steel nail would be around C20.
I have also experimented with the inserted bar, finding that it is
critically important that the bar is seated well all along its
length. If there are any sections where the bar is not being
supported by the cast iron groove the tone will be weak and short at
that point.
The other question of course is how many manufacturers are actually
hardening bars. Of the two that I know of, Yamaha and Steinway,
neither of them are hardening the front duplex bars. One of the
reasons why I suspect that Yamaha stopped using the inserted bar was
that with the combination of string approach angle, bar radius and
hardness they were using, there were quite a few string breakages. I
have found that string breakages are definitely more common when the
bar is hardened, if the piano is being regularly serviced by a
technician who drags the strings all over the shop during tuning. If
the tuning is carried out with minimal string movement once the piano
has fully settled down, I have found that the string longevity on
pianos with hardened bars is very good.
I've just published a page on my website, which is actually a
"more-information" page for the Australian market, and supplementary
to a small advertisement we are running in Limelight magazine (a link
to the page is included in the ad'). The page is mostly a promo' for
rebuilding during the economic down turn, but you can see the front
duplex images down the page in the 'Photogallery' section. There is
some explanatory text under each image.
http://overspianos.com.au/more_info.htm
On the page I have images of a D which we rebuilt recently, with an
image of a new Hamburg Steinway immediately below it. Both images
show a close-up of the front duplex bars. Steinway don't harden their
front duplex bars, and I suspect that this is why they use such a
flat top surface. We shape the front duplex bars down to the same
radius as we use for the capo, and harden them also. For some pianos,
when the customer is prepared to pay the cost, we grind off the front
bars completely and make new front duplex bars. This allows us to
relocate the bars closer to the capo, to reduce noise, and to set the
front duplex distance to a de-tuned length, with respect to the
speaking length of each note. This helps to further reduce string
noise. But I believe that the biggest factor in counter-bearing noise
is length. Make them shorter and noise reduces.
At this time David, we have settled on hardening the original capo
bar after profiling, ie. we don't use the inserted rod idea. This is
not without its problems. The most usual is that many manufacturers
repair flaws (blow holes and such) in their capo bars by drilling and
fitting a plug (which is probably made from mild steel) into the bar.
This is very common in Steinway pianos, which unfortunately is the
piano which we rebuild more than any other brand. The plugs will not
harden because their carbon content is too low. We have been grinding
them down with a die grinder and welding the hole with cast iron.
This is a difficult process and we often have to repeat a repair,
since it is common to have the repaired fillet crack post hardening.
The other problem with hardening is that a lot of paint and filler
gets burned off the bar during the hardening. Over the years we have
gotten better at this, so we burn a lot less of the paint than during
our first year of hardening (1995).
Hardening still is a big job if it is taken on as part of the
rebuilding process. I still believe it is worth it, because the tone
in service sounds like a new piano for longer. I also believe that it
is worth hardening the front bars. For domestic clients who typically
have their piano tuned only annually we reshape the front bar but
leave it unhardened. But for commercial clients I regard hardening
the front bar as essential.
>Secondly, if I were to do that to a piano where I have some concerns
>about the hardness and or consistency of the capo, what specific
>material and diameter would be best to use for the rod insert?
My experience is that the inserted rod option is more trouble to fit
compared to the work involved in shaping and hardening. So we
continue to reshape and harden. If you harden an S&S bar today you'll
now be rebuilding to S&S standard, which clearly is not strictly
their own standard, it is something which they took from somebody
else.
I can't comment on recent US Steinway D bars since I've only rebuilt
one 1925 piano, and that was back around 1990, when we were reshaping
but not hardening (we see very few US made S&S in Australia). All our
other S&S rebuilds have been Hamburg instruments. Our first D, in
which we hardened the bars, was for Queensland Conservatorium.
Steinway wrote a damning report, criticising us for hardening the
bar, saying that we 'knew nothing about tone-building the Steinway
piano' (I have a copy of the report, which was kindly and anonymously
faxed to me by an unknown supporter). They claimed that we had ruined
the piano and that it would have to be sent back to Hamburg to have a
new plate fitted. This banter went on for six months, during which
time I got very little paid work done. After months of shouting down
the phone, the problem subsided. Eventually, the institution was
talked into a new D. The 'modified' instrument ended up in the hands
of a dealer, who was a known slick operator but he also was quite a
piano player. I heard reports that he claimed it was one of the
nicest Ds he had played - not that it means much, but it felt like a
little compensation for the effort and trouble we had been through.
I don't know when Steinway actually started hardening their bars (if
anyone has this information I'd like to know), but it certainly was
happening by 2000, since we've rebuilt a 2000 D which had hardened
capo bars. On this particular instrument the hardening had shelled
off at the lowest end of the capo, so we had to re-profile the bar
and harden it again, but I'd say that most of the time with these
pianos it should be possible to simply fit new wire, although the
front duplex bars are soft and of a large radius, and I do believe
that the front bars are a source of noise also. We've found that the
pianos are a bit cleaner, even if we just reshape and harden them,
without fitting a new re-positioned front bar.
Since S&S are now having all their plates for both Hamburg and NY
made at their Kelly foundry, it would be interesting to know if they
are hardening the capo's for the US pianos. If any of you have a late
US D in your care, check out the capo bar surface with an inspection
mirror. If you can see string grooves where the strings have been
moved, they are not hardened. If the strings can be moved easily
without marking the bar they are hard. I'd be interested to know. It
is quite possible that the US bars are not being hardened, because
the Hamburg plates are being hardened in Hamburg after the plates
arrive from the US (I've got a photo of the machine they use for the
process - which a visitor to the plant, at a certain time, sent to me
via email from somewhere which shall remain un-named).
Sorry for the length of this post. I'd better go to work. I'm
currently getting covered in compound buffing another model O
rebuild, which is a bit of a yawn since the client wasn't prepared to
fork out the funds for the cost of a tenor bridge (the economic
downturn killed off the tenor). But I've done the maths for this
model now. It looks like a very suitable model for an upgrade.
Ron O.
--
OVERS PIANOS - SYDNEY
Grand Piano Manufacturers
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Web http://overspianos.com.au
mailto:ron@overspianos.com.au
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