No subject

[Michael J. Wathen]

Yesterday I got a call from a rebuilder who was dismayed and perplexed. He
was ready to ship a piano out the door hoping to collect his earnings from
a happy client. The problem was that everytime the tuner attempted to bring
the last three or four notes up to pitch they broke.  After replacing the
wire a few times they decided to change the guage but the strings kept
breaking. The breakage occurred at the coil.

note		gauge 		hz		tension		%Br		Speaking length
88		0.031		4186		207.49			85.41		2 5/16
87		0.031		3951		194.98			80.26		2 3/8
86		0.031		3729		192.47			79.23		2 1/2
85		0.031		3520		184.61			75.99		2 19/32
84		0.031		3322		184.85			76.09		2 3/4
83		0.031		3136		186.94			76.95		2 15/16
82		0.031		2960		174.60			71.87		3
81		0.031		2794		178.87			73.63		3 7/32
80		0.031		2637		175.39			72.20
79		0.031		2489		174.15			71.68

I did this on a spreadsheet and quickly changed the speaking lenghts to get
everything around 72% of breaking point.

Revised Chart

note		gauge 		hz		tension		%Br		Speaking Length
88		0.031		4186		175.21			72.12		2 1/8
87		0.031		3951		175.00			72.03		2 1/4
86		0.031		3729		178.27			73.38		2 13/32
85		0.031		3520		175.75			72.34		2 17/32
84		0.031		3322		176.61			72.70		2 11/16
83		0.031		3136		176.13			72.50		2 27/32
82		0.031		2960		174.60			71.87		3
81		0.031		2794		178.87			73.63
80		0.031		2637		175.39			72.20
79		0.031		2489		174.15			71.68

Here is the question: why can't this problem be fixed by just changing the
wires sizes?  Is it true that one cannot build a piano where the speaking
length for note 88 is greater than 2 1/8?  


Michael J. Wathen			For Information about Wapin click on URL below
michael.wathen@uc.edu		http://ucccm56.ccm.uc.edu