Short Treble (sustain?)

[Overs Pianos]

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>In a message dated 10/31/2003 10:28:57 AM=20
>Pacific Standard Time, collin.s@skynet.be writes:
>
>Thanks again, Joe.  This helps a lot.  I'm=20
>definetly not going to recap the bridge.  I'm=20
>afraid I could have to be going for a new board.=20
>(Strange, I have never seen varnish on bridges=20
>here.  In Bechstein pianos, even no graffite.)
>
>St=E9phane Collin.
>
>        Varnish is to soft to be a bridge coating=20
>IMHO even if it went on first & graphite doesn't=20
>do much to protect a bridge topeither. I've been=20
>apllying several coats of shellac to NEW bridge=20
>tops. It seals it nicely and it's hard when=20
>dry. It also allows the beauty of the nicely=20
>quartered maple to come thru. I sand it smooth=20
>with fine paper then polish it with a rag. Now=20
>obviously this is done before the pins & strings=20
>go on. Right?
>    Dale

Dale and St=E9phane,

I agree with your approach Dale. Similarly, I=20
believe it is critically important that the=20
bridge is envelope-sealed and that the chosen=20
material should have a minimum of hysteresis=20
loss. We currently use a polyurethane sealer=20
which is quite a brittle material (we cover the=20
sound board & cutoff panel, bridges and the=20
action-bay in one spray session - with the pin=20
block removed). For some time we have chosen not=20
to apply a black slip coating on the bridge cap.=20
I believe a black coating can result in an=20
overheated and damaged bridge cap under stage=20
lighting. Furthermore, as Dale mentioned, a clear=20
coat allows the beauty of the quarter cut bridge=20
cap to show through.

Regarding the hysteresis loss of bridge coatings=20
(or indeed of the bridge cap itself), I am not=20
much of a fan of the string being in contact with=20
the bridge cap at all. Therefore, the idea of a=20
bridge agraffe would seem to have (in principle)=20
considerable merit. The image below is a=20
grey-scale jpeg of the latest Stuart piano=20
agraffe.





The use of a high hysteresis material (such as=20
silicon rubber) on the body of the agraffe would=20
seem to negate a major benefit of using the=20
device. Of course, if there is such a small=20
clearance between the agraffe body and the=20
strings that it causes string noise, one would=20
have little choice but to use a lossy material as=20
a 'cure' (apart from redesigning the agraffe=20
which would be a better solution). Silicon on=20
noisy agraffes 'kills' the tone nearly as=20
effectively as damping out the front duplex to=20
'cure' string noise.

By the way Joe G., when the topic "Clamps" was=20
active last week, you asked what "RHS" referred=20
to. It is a standard Australian term in the steel=20
industry for Rectangular Hollow Section. RHS is=20
supplied in a variety of dimensions and wall=20
thicknesses, and is manufactured by rolling a=20
flat section into the required shape and seam=20
welding it. As supplied, its dimensional accuracy=20
is adequate for most construction applications.=20
In terms of strength per unit cost, RHS is=20
considerable cheaper than I beam or H section.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
_____________________________

Web http://overspianos.com.au
mailto:info@overspianos.com.au
_____________________________
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