On Fri, 27 Sep 2013 16:31:09 +0100, N_Cook wrote:

On 27/09/2013 15:53, Adrian Tuddenham wrote:
wrote:

On Tuesday, August 4, 2009 10:38:19 AM UTC-4, N_Cook wrote:
[...]
How about a longish length , folded 6 times until 64 wires. Maybe
longer/more bulk. Hand twist together until it will not sensibly tighten any
more. Take average diameter, use packing factor allowance, and infer for 1
wire diameter,..

Make the bundle by winding the wire 32 times around two spaced pegs so
as to be certain that all the 64 wires this produces between the pegs
are parallel and not intertwined. Slip the wire off the pegs and do not
twist it, but squeeze the parallel section so that it takes up a
cylindrical shape.

Wrap another length of the same wire tightly around the outside of the
cylindrical section for a known number of turns (20 at least). Unwind
the wire and measure its length and divide by 20 to calculate the mean
circumference of one turn.

Do exactly the same thing with a length of wire whose diameter you do
know (probably something much larger, so that you can measure it
easily). You may not be able to wrap as many as 20 turns, so adjust
the divisor accordingly.

The ratio of the lengths of the one-turn circumferences will be the
square of the ratio of the wire diameters.




Friday afternoon after a long tiring day yesterday, I cannot
thought-experiment my way into this. I'll have to have a go with some
thicker wire to start with, to work out the method you've outlined

Why not measure the resistance and calculate the diameter from that?
(Assumes the wire is just copper and is round).