Bass string scaling question

[John Delacour]

At 12:13 am -0700 26/5/07, David Love wrote:

>What is the maximum differential between the core wire diameter and the
>outer wrap diameter before you need to go to double wraps?

There are two questions here : first, what harmonic distribution are 
you aiming for in the string, and second, what is actually possible 
from the string-maker's point of view.  I'll answer the second:

Too thick a single cover on a thin core wire will at best cause the 
flattening to twist and at worst cause the wire to break on the 
machine.  To give a real example off the top of my head (with 20 
years of commercial string-making experience as a guide), if you take 
a No. 20 (1.125 mm.) core for the top single -- anything thinner 
being rather unusual -- then you could continue with single covers on 
this core, if you so chose, up to 1.75 mm. in diameter.  At that 
point the string-maker (at least this one) would begin to hold up his 
hands.  The minimum core required for a 2.00 mm. cover (the thickest 
in common use) would be a No. 22 (1.225 mm) and that would be risky. 
You will rarely find a 2.00 cover on a core wire less than No. 24. 
The reason is that a certain tension is required to achieve a good 
tight cover and that tension cannot be applied unless the core wire 
will survive it without twisting so much as to turn the flattening 
into a spiral and/or snap.

 From this you will see that one has a fair degree of latitude, since 
the thinnest core you are likely to specify is capable of taking a 
fairly thick cover.  To give a simple answer to your question, I 
quickly typed into Excel a column of core diameters followed by a 
column of the diameter of copper I would normally regard as a maximum 
for the given cores in practice, and the results were rather neat, 
showing that a cover 55% thicker than the core is the thickest I 
would normally be appy to use, and I think other string-makers would 
give you a similar answer.

JD