Hi Joe

Correction this line my post above
"
The weight of the wire and the tension applied to it need to be added, they do not change so can be stored constants.
"

Should read
The weight of the wire does change according to its length.

Roslau are are a world leader in music wire manufacture.

This is where I sourced my wire. https://parkepianostrings.com.au/pia...als-and-tools/
It costs about $40 AUD per coil plus post. they will ship internationally.

Half KG coils of #2 .010" Roslau Blue music wire contain 1250 metres of wire.

Regards
John