C88 length, was relevance of bridge pin spacing

[Ron Overs]

Hi all,

The nominal C88 standard for the Hamburg D used to be 53 mm. They 
appear to have reduced their C88 length to 49 mm in their latest 
iterations (since at least 2000). I'm rebuilding a circa 2000 piano 
at the moment - in which we're completely re-scaling the treble 
sections.

Their latest Ds are heavier in the hitch plate area (which I prefer), 
and the scale is fully revised to be shorter than previously, but 
still does not conform to an accurate log-style scale. While overall 
it looks to conform more or less to log style, there are significant 
note to note variations. The breaking percentage with the new scale 
is even lower than previously at note F21. So I don't suppose we can 
expect to see a scaling improvement in the clones any time soon.

For all of the Overs 225 pianos we have produced to date, we have 
used 53 mm for C88. This length does put the wire under considerable 
stress when using smaller radius hardened bars. I've had a few more 
string breakages with this speaking length than I would like, and I 
suspect that this may be why S&S have taken their speaking length on 
the D back to 49 mm.

Frank's post regarding spacing concurs generally with my own 
practice. I have a spreadsheet which is incorporated in the overall 
scale design spreadsheet, which calculates the rear pin row offset 
with respect to the XY location of the front row pins. This allows us 
to alter the front/rear pin spacing to ensure that there is no 
intersection of the bridge pins within the bridge.

I also note that some piano 'designers' have been known to shift the 
front pin row instead of the back pin row, to avoid intersection 
conflicts. They should be referring to some basic piano-design 101 
rules here. The disastrous effect this practice has on tunability and 
stability should be more than obvious.

Happy new year,
Ron O.

>  >  Original for this piano was 53mm. I have looked at 54 and 52 - 
>neither > will work out much more than the top octave. So 53 appears 
>to be ideal > for this piano.
>
>For me, note 88 is always 54mm, regardless of the size of the piano, 
>but then I am not trying to make everything fit on an existing 
>bridge.  I am always starting out with a blank sheet of paper (i.e. 
>cyber space).
>
>Frank Emerson


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OVERS PIANOS - SYDNEY
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