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At 9:58 PM +0000 4/11/03, Michael Gamble wrote:
>
>Why not see what response your observations get from
>Grotrian-Steinweg themselves?
The recapping job I mentioned was undertaken back in 1989. I have
observed since then, many other instruments from the same manufacture
with similarly inappropriate bridge pin spacing (often with the
resultant elongated or completely collapsed bridge pin holes).
Furthermore, with regard to the piano repair in question, the
intention originally was to recap the treble bridge only. After
re-cutting the notching and re-drilling the bass bridge in
preparation for the oversize bridge pins, we found that the front and
rear pins (in the bichord section) were running into each other
towards the bottom of the bridge pins holes. To explain further,
while driving the back scale pins they were running into the speaking
length pins somewhere below the bridge cap.
I was absolutely less than impressed at the time. Since we had to
turn around and recap the bass bridge and re-position the back row of
pins to cure the problem. If a factory, which lays claim to making a
quality piano, can't even get the bridge pin field laid out so that
the pins don't run into each other below the bridge cap, I can't see
the point in contacting them to tell them about it. After all, most
messengers usually get shot, and what would a small time piano
re-builder down in the colonies know about the problem anyhow?
>Do you mean Model 220? Or should it be Model 225?
The Grotrian seven foot class of grand piano in the early '70's was a
220. A 223 was released sometime after 1975 (my first year working
with pianos).
> I have a superb 225 on my rounds and have been corresponding with
>Grotrian on the subject of a 10 year service/regulation.
The 225 is a later piano again. Would you measure the bridge pin
spacing, in the highest treble string section, between the outside
unisons (centre to centre) next time you see it? I'd be interested to
know if they are still building them the same way.
Ron O.
>They have been most helpful. Write to: Burkhard Kaemmerling at:
><mailto:kaemmerling@grotrian.de>kaemmerling@grotrian.de
>Regards
>Michael G (UK)
>----- Original Message -----
>From: <mailto:sec@overspianos.com.au>Overs Pianos
>To: <mailto:pianotech@ptg.org>Pianotech
>Cc: <mailto:alfailsa@accsoft.com.au>Alf Reichardt
>Sent: Monday, November 03, 2003 10:21 PM
>Subject: Re: Short Treble (sustain?)
>
>Del, Ron N. and all,
>
>The string buzzing on the side of the agraffe slot is most certainly
>the problem. Earlier in my career I recapped the failed bridges on a
>Grotrian 220. Since the owner was travelling to Germany on business,
>when he visited the factory they sold him a replacement treble
>bridge cap. Unfortunately, the new bridge cap was afflicted with the
>same 'disease' which was common to '70s era Grotrians (I have no
>idea if it remains a problem with their contemporary instruments).
>However, the bridge pin spacing was so close that there was
>virtually no free space between the string and the adjacent bridge
>pin. Consequently, there remain several notes on my client's
>Grotrian 220 which have string noise at the bridge pins (which
>varies in intensity according to the relative humidity at the time).
>A gentle side pressure on an offending bridge pin will stop the
>noise.
>
>These Grotrian bridges from the '70s are prone to failure on account
>of the close bridge pin spacing. There is simply insufficient bridge
>wood around the pins to provide adequate support for the side thrust
>on the pins. On Grotrians from earlier periods they have used a
>wider bridge pin spacing and they do not have the same problem.
>Isn't it amazing how corporate knowledge often fails to be passed
>down from one generation to another? The 'Johnny come latelys' turn
>up with new thinking but fail give appropriate consideration to
>lessons learned long ago by an older generation of thinkers. I'm all
>for innovative technologies, but one should come to it after
>stepping off from the knowledge which has gone before.
>
>Clearly, the idea of placing a damping material on a noisy string
>segment (wether it be new-age silicon as in the case of the Stuart
>agraffe, a piece of felt or a lump of fat from under the barbecue),
>its still is just a case of fixing the symptom instead of addressing
>the cause of the disease.
>
>The bridge agraffe we have been discussing is a case in point. It
>simply wasn't thought through prior to execution. I concur with your
>views Ron N. and Del, with regard to widening the slots and using
>rolled pins as a solution. Less overall height would be a plus as
>well. As you and I have both mentioned previously Ron N., it would
>allow for the retention of a more sensible bridge height and
>stiffness.
>
>Ron O.
>
>>----- Original Message -----
>>From: "Ron Nossaman" <RNossaman@cox.net>
>>To: "Pianotech" <pianotech@ptg.org>
>>Sent: November 01, 2003 8:23 PM
>>
>>Subject: Re: Short Treble (sustain?)
>>
>>
>>I suspect the problem is with the string buzzing against the side of the
>>
>>slot.
>>
>>
>>Del
>>
>>
>> Perhaps, though I have a hard time imagining much vibration excursion in
>>
>> that short segment. At that, how difficult or more expensive is a wider
>>
>> slot, as long as you're cutting one anyway? It's not like it will cost
>>
>> anything important in rigidity. A grooved center rod would help too,
>>
>>though
>>
>> it would cost a bit more to produce.
>>
>>
>> Ron N
>>
>>
>>-------------
>>
>>As do I. I did think it a possibility, though, as I worked with similar
>>devices at Baldwin. The easiest way to solve the problem (if it exists)
>>(and, other than putting some damping material between the leading
>>termination and the center deflector rod) is, as you suggest, to groove the
>>center rod. This could be rolled and, in quantity, is not as expensive as
>>you might think. In limited quantities, however, it might well be a factor.
>>This can be used to solve another problem as well -- the varying string
>>deflection angles as the wire size changes. I played around with several
>>groove depths, deeper in the low tenor and bass, more shallow in the
>>tenor/treble.
>>
>>Del
>>
>
>--
>OVERS PIANOS - SYDNEY
> Grand Piano Manufacturers
>_______________________
>
>Web http://overspianos.com.au
>mailto:info@overspianos.com.au
>_______________________
--
OVERS PIANOS - SYDNEY
Grand Piano Manufacturers
_______________________
Web http://overspianos.com.au
mailto:info@overspianos.com.au
_______________________
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