Next size larger bridge pins

[Ron Overs]

We regularly repin bridges with oversize pins where appropriate (if the 
bridge wood is without surface checks yet the pins have elongated the 
holes).

Yes, our repinned bridges are cleaner in tone than the original bridge.

Robert Goodale wrote,

>First, the strings in each section are scaled to fit a specific pin size,
>(unless of course we are talking about a Winter spinet which never changes
>sizes).  

I would be curious to know which piano designers might lay out bridges or 
scales in this manner.

>This is very important because of false beats. I have seen several
>pianos over the years where someone replaced pins with the next size.  Tuning
>was a nightmare and the tone quality was decisively diminished.

While I don't doubt Robert's claim, I must question the conclusion he has 
drawn from his observations. Conversely, over the years I also have seen 
original factory pianos, with original bridge pins, which have had false 
beats and 'Tuning was a nightmare' (we all experience them once in a 
while).

Could it be that the particular repinning jobs, which Robert has 
experienced, might not have been executed to a standard the equivalent of 
a decent OEM bridge job.

I have had the opposite experience to Robert. I have had several 
experiences (on a continuous basis over the past fifteen years) where we 
have replaced the original bridge pins with oversize bridge pins, and the 
tonal quality of the piano has improved from false to clean. I am not 
suggesting that loose bridge pins are the only causal agent of falseness. 
But they're are certainly part of the picture in some pianos.

Variable string offset angles (or downbearing), within a unison group, 
has been shown to contribute to falseness also. So it is possible that 
sloppy marking out of the bridges can lead to falseness.

The late Fred Sanger, formerly a tuner for Marshall and Rose in the UK, 
said that when he was at Marshalls in the early sixties, there were two 
belly makers in the factory. He noticed that the pianos from one bellyman 
were invariably clean toned, while those from the other were invariably 
false to tune. Obviously, 'good' piano tone comes about through a 
combination of good design and careful workmanship.

We have been using quite a lot of Renner bridge pins for our bridge 
pinning work in recent years. We used to get silver steel rod centreless 
ground to the exact oversizes we required when installing oversize bridge 
pins. But the Renner pins are OK and they're a lot cheaper. However, we 
have found it necessary to grind the points, right where the parallel 
side of pin ends and the point starts, to prevent the small burr on the 
bridge pin from damaging the bridge wood during insertion. We have been 
using a very fine finishing grindstone (which we normally use for the 
final grind for chisels etc.) to ensure that the pin surface has no burr 
to damage the hole.

Furthermore, a bell-mouthed bridge pin hole is not suitable for an 
oversize bridge pin. The bridge wood must exert an even tension (ie. as 
even as possible) from the bottom to the top of the bridge pin hole. 
Therefore, we consider it important to redrill the bridge pin holes to 
establish a uniform diameter from top to bottom prior to repinning. A 0.1 
mm step drill set  is required for this work.

Regards,

Ron Overs

Overs Pianos, Sydney Australia
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Email:   sec@overspianos.com.au
Website: www.overspianos.com.au
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