[CAUT] Duplex scale noise, piano rebuilding

[William Schneider]

Hi Don

If it's really inharmonicity that's the problem with these few notes,
changing the strings should help (Don't use a rubber to stretch them). Maybe
it's loose bridge pins or a rough capo.

If they are wildly untunable you might also check the down bearing on the
front of the bridge there. Often downbearing is spoken of generally without
reference to whether the measurements taken will reflect the string
deflection at the speaking segment, as opposed to the hitchpin segment.
Hitchpin segment deflection is nice, but speaking length deflection is
mandatory. I have seen plenty of instances, including on new quality pianos,
where the rear downbearing is so great that it has actually pressed down the
bridge to the point that the speaking segment has ridden up its bridge pin.
In such a case there is actually negative front bearing, even though a dial
indicator with the plunger set in the center of the bridge shows a great
reading. By sliding the indicator fore and aft, you can see the measurement
change, and determine where the bearing really is. If the string has ridden
up the bridge pin due to this sort of problem, pressing and holding it down
just behind the front bridge pins with a screwdriver blade should improve
the tunability and the tone immediately. It's no use expecting the strings
to stay down; you have to either reduce back bearing to let the bridge
rise(by shimming aliquots), or slope the bridge cap slightly down at the
rear(by planing), and touch up the rear notches with a chisel. By the way a
piano with good front bearing throughout the scale is a completely different
animal than one with downbearing measured before stringing only with a shim
placed on the plate by the hitch pins(a very common method when
manufacturing or rebuilding). You get much more tone and much better
sustain, with markedly fewer false beats. 

Bill Schneider



-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
Wigent, Donald E
Sent: Tuesday, November 21, 2006 10:40 AM
To: College and University Technicians
Subject: Re: [CAUT] Duplex scale noise, piano rebuilding

Hi gang:  I have a mason in a Church that the top 3 notes have an
absolutely terrible inharmonisity and I have no idea what to do that is
if there is something that can be dun. The piano was (rebuilt) in TEN so
any thing is possible. Otherwise it is a pretty nice box. 
Don Wigent 
E C U     

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
Ron Nossaman
Sent: Monday, November 20, 2006 1:18 PM
To: College and University Technicians
Subject: Re: [CAUT] Duplex scale noise, piano rebuilding


>  As for me... I just want to
> be like Ron and Vince when I grow up :-)
> 
> Jim Busby BYU


Uh, Jim, in that case I'm afraid you might have to rethink 
that growing up part.

Ron N