Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?

On Tue, 04 Aug 2009 15:38:19 +0100, N_Cook wrote:

Not the first time I've met this problem. Say nominally about 0.05mm .
With a micrometer, how much are you compressing it? could easily be out
by 20 percent out and squaring that if using weight to length via
density or resistance calculation via resistivity, is very iffy.
If access to a microgram resolution of weighing scales then a few metres
of the wire and density of copper and allowance for enamelling , but no
highly accurate weighing machine. Optically comparing under a microscope
needs known diameter standards.
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, how better accuracy might that be.? If I start from
known good coil of say 46swg enamelled wire and do this 64 wire trick ,
to work backwards, how accurate/reliable would the manufacture sizing be
?
Any other ideas?

In my analytical work on failed electronics, I would take a wire like
that and mount it vertically in a mounting medium that is used for cross-
sections. I would mount several samples near to each other. Then I would
cross-section the mount and measure the diameters using a microscope with
a calibrated filer eyepiece. The diameters with/and without the coatings
would be provided to the customer along with an average value.

At the time I was doing it, my lab would charge about $100 for that.
Depends how important it is to you for spending that much. Since I am
retired, I'm sure it's more expensive now.

Here's a thought...

If you could find a table of resistance-per-unit-length for various wire
gauges, and had an ohmeter that could accurately read low resistances...

In article , "William Sommerwerck" wrote:
Here's a thought...

If you could find a table of resistance-per-unit-length for various wire
gauges, and had an ohmeter that could accurately read low resistances...

I thought getting good contact would be a problem. Soldering might work.

If you could not get an optical scale, perhaps a printer could be used to make a scale.
600 dpi would be less than .04 mm.


greg

On Aug 4, 11:54*am, (GregS) wrote:
In article , "William Sommerwerck" wrote:

If you could not get an optical scale, perhaps a printer could be used to make a scale.
600 dpi would be less than .04 mm.

greg

Interesting idea! I need an inexpensive optical scale from time to
time.

I have some 8.5 by 11 inch thermally stable paper printed in
Switzerland that has 300 lines per inch printed diagonally on it.
Yes, that's 150 black, 150 white per inch. Got 10 sheets at the
bargain price of $300 per page and these were 1980 prices.

In a printer doesn't the single blop of ink/laser powder spread out
over more than 3 to 4 of those pixels? Does gray scale modify the
density? Or, do printers still use those pseudo patterns to generate
gray scale?

Is there anybody out there to try this, look at it under a microscope,
and let us know?

Robert

On Aug 4, 9:34*am, "William Sommerwerck"
wrote:
Here's a thought...

If you could find a table of resistance-per-unit-length for various wire
gauges, and had an ohmeter that could accurately read low resistances...

One uses a "4 terminal" ohmmeter.
To do this easily, use one DVM on ohms and connect it to as second DVM
on current to measure the 'ohms current' ; it is usually an even
current like 1mA , 10mA etc. Note the value. Then connect the ohmmeter
to the ends of the wire under test. Take the second DVM on mV and
measrue the voltage across a precise length of the wire under test.
Since that is a voltage [high impedance] measurement, contact
resistance has relatively little effect on accuracy.
One should also take into account the temperature, then plug it into
the resistance formula and arrive at the area then reduce that to a
diameter.

Neil S.

In article ,
"N_Cook" wrote:

Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?

You only need two things:

1. A toolroom micrometer (not to be confused with a homeowner mic, or a
machinist's shop mic.)

2. The skill to use it.

I can't think in fractions of a millimeter very well, but a good
toolroom mic will read directly to 0.0001", and inferentially to
0.00001" within +/- 0.00002" or so.

The trick to not "crushing" the wire is to use the wire like a feeler
gauge, between the jaws of the mic., closing the mic slowly while
feeling for friction.

We buy 42 AWG single poly for guitar pickups, and order it specifically
as "min to nom." (minimum to nominal diameter.) The supplier checks his
stock with a toolroom mic, and ships only those spools on the low end of
the tolerance range. We verify it before putting it to use.

On Aug 4, 10:02*am, Smitty Two wrote:
In article ,

We buy 42 AWG single poly for guitar pickups, and order it specifically
as "min to nom." (minimum to nominal diameter.) The supplier checks his
stock with a toolroom mic, and ships only those spools on the low end of
the tolerance range. We verify it before putting it to use.

I would like to email directly and discuss winding guitar pickups.
Please email:
robert DOT a DOT macy AT gmail DOT com

Where do you buy 42 Awg wire?

We buy small quantities of 30-36 Awg at exceptionally competitive
pricing from
Fay Electric Wire Corp. (800) 245-9473
752 North Larch Avenue
Elmhurst, IL 60126
[not associated with them, or gain by posting this.]

Robert

Robert Macy wrote in message
...
On Aug 4, 10:02 am, Smitty Two wrote:
In article ,

We buy 42 AWG single poly for guitar pickups, and order it specifically
as "min to nom." (minimum to nominal diameter.) The supplier checks his
stock with a toolroom mic, and ships only those spools on the low end of
the tolerance range. We verify it before putting it to use.

I would like to email directly and discuss winding guitar pickups.
Please email:
robert DOT a DOT macy AT gmail DOT com

Where do you buy 42 Awg wire?

We buy small quantities of 30-36 Awg at exceptionally competitive
pricing from
Fay Electric Wire Corp. (800) 245-9473
752 North Larch Avenue
Elmhurst, IL 60126
[not associated with them, or gain by posting this.]

Robert


I have emailed to you

Smitty Two wrote in message
news
In article ,
"N_Cook" wrote:

Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you
compressing
it? could easily be out by 20 percent out and squaring that if using
weight
to length via density or resistance calculation via resistivity, is
very
iffy.
If access to a microgram resolution of weighing scales then a few metres
of
the wire and density of copper and allowance for enamelling , but no
highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this
64
wire trick , to work backwards, how accurate/reliable would the
manufacture
sizing be ?
Any other ideas?

You only need two things:

1. A toolroom micrometer (not to be confused with a homeowner mic, or a
machinist's shop mic.)

2. The skill to use it.

I can't think in fractions of a millimeter very well, but a good
toolroom mic will read directly to 0.0001", and inferentially to
0.00001" within +/- 0.00002" or so.

The trick to not "crushing" the wire is to use the wire like a feeler
gauge, between the jaws of the mic., closing the mic slowly while
feeling for friction.

We buy 42 AWG single poly for guitar pickups, and order it specifically
as "min to nom." (minimum to nominal diameter.) The supplier checks his
stock with a toolroom mic, and ships only those spools on the low end of
the tolerance range. We verify it before putting it to use.

Yes for the Landola pickup, the number of turns from measuring wire diameter
then weight/weighted circumferences and also by the 7.7Kohm ,assuming both
pickups are the same then this gives the same number , but does not agree
with counting a sample 1000 turns and ratioing , they were in fact laquered
together to defeat counting-off

For 2 reels of enamelled wire labelled as 2.4 thou/mil and 2.8 thou/mil and
my micrometer that has a 2Kg closure force (just checked via spring and
kitchen scales) before the torque clutch disengages.
I have to DIVIDE the reading by 1.15 for the 2.4 thou wire and 1.25 for the
2.8 thou wire. I suppose this is to do with the enamel thickness and the
wire is specified as the metallic diameter. I assume my wire gauge v
wight/resistance tables are for bare copper, not actually specified.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

In article ,
"N_Cook" wrote:

they were in fact laquered
together to defeat counting-off

They were in fact laquered together, hopefully in a vacuum chamber, to
keep them from buzzing.

On Aug 5, 7:38*am, Smitty Two wrote:
In article ,

*"N_Cook" wrote:
they were in fact laquered
together to defeat counting-off

They were in fact laquered together, hopefully in a vacuum chamber, to
keep them from buzzing.

Jon,

Could not reply to your email, so replying he

Thank you. MWS is our second choice and first choice for very small
gauge wires, like 54 Awg wire
They have a wealth of technical information.
Regards,
Robert

If the coil has been covered in lacquer, then repeated soakings in lacquer
thinner should remove the lacquer that was used to bind the coil.

Some careful, light brushing, and agitation could speed up the removal. It
should become apparent when the lacquer has been removed as all of the
windings will be loose, and a final rinse in clean thinner should be enough
to remove any traces.

It would probably be helpful to have a jig/form handy to place the coil
windings on, something like two spaced dowels about the same size as the
inside dimension of the coil, mounted to a piece of wood or other material.
Then with a center point located between the dowels, the coil would turn
fairly easily for counting turns.

--
Cheers,
WB
..............


"N_Cook" wrote in message
...

Yes for the Landola pickup, the number of turns from measuring wire
diameter
then weight/weighted circumferences and also by the 7.7Kohm ,assuming both
pickups are the same then this gives the same number , but does not agree
with counting a sample 1000 turns and ratioing , they were in fact
laquered
together to defeat counting-off

For 2 reels of enamelled wire labelled as 2.4 thou/mil and 2.8 thou/mil
and
my micrometer that has a 2Kg closure force (just checked via spring and
kitchen scales) before the torque clutch disengages.
I have to DIVIDE the reading by 1.15 for the 2.4 thou wire and 1.25 for
the
2.8 thou wire. I suppose this is to do with the enamel thickness and the
wire is specified as the metallic diameter. I assume my wire gauge v
wight/resistance tables are for bare copper, not actually specified.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Wild_Bill wrote in message
...
If the coil has been covered in lacquer, then repeated soakings in lacquer
thinner should remove the lacquer that was used to bind the coil.

Some careful, light brushing, and agitation could speed up the removal. It
should become apparent when the lacquer has been removed as all of the
windings will be loose, and a final rinse in clean thinner should be
enough
to remove any traces.

It would probably be helpful to have a jig/form handy to place the coil
windings on, something like two spaced dowels about the same size as the
inside dimension of the coil, mounted to a piece of wood or other
material.
Then with a center point located between the dowels, the coil would turn
fairly easily for counting turns.

--
Cheers,
WB
.............


"N_Cook" wrote in message
...

Yes for the Landola pickup, the number of turns from measuring wire
diameter
then weight/weighted circumferences and also by the 7.7Kohm ,assuming
both
pickups are the same then this gives the same number , but does not
agree
with counting a sample 1000 turns and ratioing , they were in fact
laquered
together to defeat counting-off

For 2 reels of enamelled wire labelled as 2.4 thou/mil and 2.8 thou/mil
and
my micrometer that has a 2Kg closure force (just checked via spring and
kitchen scales) before the torque clutch disengages.
I have to DIVIDE the reading by 1.15 for the 2.4 thou wire and 1.25 for
the
2.8 thou wire. I suppose this is to do with the enamel thickness and the
wire is specified as the metallic diameter. I assume my wire gauge v
wight/resistance tables are for bare copper, not actually specified.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





The former has to be demountable. I've made but not had the time to try
winding yet. A platic binder spine warmed up and opened out to a flat
bottomed V. Doubled up , end over end, and 2 cuts per side , so can easily
cut the remainder after winding. Some thick PTFE wound around to decrease
the width a bit to fit the trough, some thin elastic laid across , so under
the wiring, to tie together in loops after winding. Well thats my theory.
The original one probably failed because in the process of wrapping with
tissue paper and adjusting to fit into the trough , the layup was seriously
disturbed/ stressed, before lacquering.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

In article ,
"N_Cook" wrote:

snip

Just a heads up that I emailed you per your request. My email as shown
on usenet is munged.

On Aug 4, 10:38*am, "N_Cook" wrote:
[about measuring a small copper wire]
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it?

Measuring microscope. Either a standard microscope with a
micrometer-driven stage and a crosshair reticle, or a microscope
mounted on an X/Y translation mechanism (calibrated, of course).
It's a standard item in instrument shops, and you can measure
the width to whatever edge-detection limit your microscope
has.

If the length is long enough, resistance and length will do the
same trick, BUT resistance measures average resistance
(average of radius squared), not average of radius.

On Tue, 4 Aug 2009 15:38:19 +0100, "N_Cook" wrote:

Any other ideas?

Get a magnifier with replacable reticles:
http://www.measuringmagnifier.com
http://www.tedpella.com/magnifier.htm
http://www.emsdiasum.com/microscopy/products/magnifier/measuring.aspx?mm=18

If your wire is microscopic and too small for a 8x or 10x magnifier,
get a reticule (or graticule) for a microscope:
http://www.reticles.com/ordering.htm
http://www.microscope-depot.com/reticles.asp


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

N_Cook wrote:

Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?


I wind 100 turns of fine gauge wire on a smooth rod and measure the
length with good calipers, then divide by 100. If there isn't enough
for a good measurement, wind 200 turns.

Or spend $50,000+ US for a precision optical measuring machine made
to monitor the diameter of wire as it is made or spooled.


--
You can't have a sense of humor, if you have no sense!

I wind 100 turns of fine gauge wire on a smooth rod ...

Tightly, of course.

... and measure the length with good calipers,
then divide by 100.


There's a story that Edison asked a young man (presumably an apprentice) to
measure the volume of several light bulbs. The apprentice stated with a
ruler, a pair of calibers, trying to get precise measurements so he could
calculate the volume. When Edison saw him fussing around, he grabbed one of
the bulbs, filled it with water, and dumped into a graduate. I suspect the
whole exercise was intended to make a point, rather than measure the bulbs.

Unfortunately, I can't think of an equivalent "clever" way to indirectly
measure the wire's diameter.

On Wed, 5 Aug 2009 07:22:55 -0700, "William Sommerwerck"
wrote:

I wind 100 turns of fine gauge wire on a smooth rod ...

Tightly, of course.

... and measure the length with good calipers,
then divide by 100.


There's a story that Edison asked a young man (presumably an apprentice) to
measure the volume of several light bulbs. The apprentice stated with a
ruler, a pair of calibers, trying to get precise measurements so he could
calculate the volume. When Edison saw him fussing around, he grabbed one of
the bulbs, filled it with water, and dumped into a graduate. I suspect the
whole exercise was intended to make a point, rather than measure the bulbs.

Unfortunately, I can't think of an equivalent "clever" way to indirectly
measure the wire's diameter.

There's always a way. Measure out a long length of wire such as 100
meters. Carefully weigh the 100m of wire. The density of copper is
8.92 gm/cm^3. The rest is math, which I won't attempt without my
morning coffee blast.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

In article ,
Jeff Liebermann wrote:

On Wed, 5 Aug 2009 07:22:55 -0700, "William Sommerwerck"
wrote:

I wind 100 turns of fine gauge wire on a smooth rod ...

Tightly, of course.

... and measure the length with good calipers,
then divide by 100.


There's a story that Edison asked a young man (presumably an apprentice) to
measure the volume of several light bulbs. The apprentice stated with a
ruler, a pair of calibers, trying to get precise measurements so he could
calculate the volume. When Edison saw him fussing around, he grabbed one of
the bulbs, filled it with water, and dumped into a graduate. I suspect the
whole exercise was intended to make a point, rather than measure the bulbs.

Unfortunately, I can't think of an equivalent "clever" way to indirectly
measure the wire's diameter.

There's always a way. Measure out a long length of wire such as 100
meters. Carefully weigh the 100m of wire. The density of copper is
8.92 gm/cm^3. The rest is math, which I won't attempt without my
morning coffee blast.

Unfortunately, if you don't know what the insulation is, you don't know
squat.

On Wed, 05 Aug 2009 20:07:34 -0700, Smitty Two
wrote:

In article ,
Jeff Liebermann wrote:

On Wed, 5 Aug 2009 07:22:55 -0700, "William Sommerwerck"
wrote:

I wind 100 turns of fine gauge wire on a smooth rod ...

Tightly, of course.

... and measure the length with good calipers,
then divide by 100.


There's a story that Edison asked a young man (presumably an apprentice) to
measure the volume of several light bulbs. The apprentice stated with a
ruler, a pair of calibers, trying to get precise measurements so he could
calculate the volume. When Edison saw him fussing around, he grabbed one of
the bulbs, filled it with water, and dumped into a graduate. I suspect the
whole exercise was intended to make a point, rather than measure the bulbs.

Unfortunately, I can't think of an equivalent "clever" way to indirectly
measure the wire's diameter.

There's always a way. Measure out a long length of wire such as 100
meters. Carefully weigh the 100m of wire. The density of copper is
8.92 gm/cm^3. The rest is math, which I won't attempt without my
morning coffee blast.

Unfortunately, if you don't know what the insulation is, you don't know
squat.

Ummm... the wire gauge is a measure of the copper diameter (or more
correctly, the cross sectional area), without the insulation. The
added weight of the insulation coating is quite small when compared to
the larger density of the copper. With flexible small diameter copper
wire, there are a few additives, but they constitute a tiny percentage
of the wire composition. My guess is the biggest error will be in the
accuracy of the weight, not in the effects of the insulation.

William Sommerwerck wrote:

I wind 100 turns of fine gauge wire on a smooth rod ...

Tightly, of course.

... and measure the length with good calipers,
then divide by 100.


There's a story that Edison asked a young man (presumably an apprentice) to
measure the volume of several light bulbs. The apprentice stated with a
ruler, a pair of calibers, trying to get precise measurements so he could
calculate the volume. When Edison saw him fussing around, he grabbed one of
the bulbs, filled it with water, and dumped into a graduate.

Poor graduate.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Microscope with a calibrated reticule.

I've got a pocket magnifier with a scale with 0.001" resolution.

If you don't have a microscope, but you can get (or borrow) some decent
(optically flat) mounting slides (and a monochromatic light source),
this might work.

Lay the wire down on one slide and then lay the other slide down on the
wire so that the diameter of the wire causes the top slide to form an
inclined plane w.r.t the bottom slide.

Measure the distance from the wire to the end of the top slide.
Illuminate this with the light source and look for diffraction ridges
(near the point of contact between the two slides). Count the number of
ridges per centimeter. Since each diffraction ridge is caused by an
increase of one wavelength increase in gap between the slides, you can
work out the angel between the slides. And by similar triangles, work
out how high the wire is lifting the top slide.

--
Paul Hovnanian
------------------------------------------------------------------
If God is perfect then why did He create discontinuous functions?

N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?


Sometimes, when a measurement is difficult, it's time to reformulate the
problem.

If your objective is to rewind a coil, take your best shot at wire size
and rewind the darn coil. If the resistance and inductance come out right,
Isn't that what you really want? If not, try different wire.
Self-resonant frequency will give you some idea whether your
winding technique matches the original for capacitance between
layers.

On Tuesday, August 4, 2009 10:38:19 AM UTC-4, N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?

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.



--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

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

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).

On 27/09/2013 16:40, Pat wrote:
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).


For this very fine wire it is only ever enamelled/lacquered wire I ever
deal with, being used as magnet wire, pick-up coils and the like

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

I believe some variation of this method was the standard way of
determining the gauge of wires many years ago. It had the advantage
that the reading was averaged over a number of wires (some of which may
not have been exactly circular in cross-section) and, once established,
could be used by anyone with a ruler to give a fairly good degree of
accuracy.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Adrian Tuddenham wrote:

I believe some variation of this method was the standard way of
determining the gauge of wires many years ago. It had the advantage
that the reading was averaged over a number of wires (some of which may
not have been exactly circular in cross-section) and, once established,
could be used by anyone with a ruler to give a fairly good degree of
accuracy.


I saw a prototype optical measuring system about 30 years ago that
was being refined to measure copper wire on the production line. It was
already accurate to under 1/1000 inch, at production speeds.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

On 9/27/2013 3:51 PM, wrote:
On Tuesday, August 4, 2009 10:38:19 AM UTC-4, N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?


Take 10 meter. Measure the resistance.
resistance is 0.0175 ohm per meter per square millimeter.
From this you can find the area.
Area is 1/4 pi d*d This will give the real copper diameter.

Two prerequisites. Pure copper and the wire is round.

On 30/09/2013 13:02, tuinkabouter wrote:
On 9/27/2013 3:51 PM, wrote:
On Tuesday, August 4, 2009 10:38:19 AM UTC-4, N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you
compressing
it? could easily be out by 20 percent out and squaring that if using
weight
to length via density or resistance calculation via resistivity, is
very
iffy.
If access to a microgram resolution of weighing scales then a few
metres of
the wire and density of copper and allowance for enamelling , but no
highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do
this 64
wire trick , to work backwards, how accurate/reliable would the
manufacture
sizing be ?
Any other ideas?


Take 10 meter. Measure the resistance.
resistance is 0.0175 ohm per meter per square millimeter.
From this you can find the area.
Area is 1/4 pi d*d This will give the real copper diameter.

Two prerequisites. Pure copper and the wire is round.



That applies to most copper wire but not these finest dimensions where
that formula breaks down

On Mon, 30 Sep 2013 14:04:04 +0100, N_Cook wrote:

On 30/09/2013 13:02, tuinkabouter wrote:
On 9/27/2013 3:51 PM, wrote:
On Tuesday, August 4, 2009 10:38:19 AM UTC-4, N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you
compressing
it? could easily be out by 20 percent out and squaring that if using
weight
to length via density or resistance calculation via resistivity, is
very
iffy.
If access to a microgram resolution of weighing scales then a few
metres of
the wire and density of copper and allowance for enamelling , but no
highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do
this 64
wire trick , to work backwards, how accurate/reliable would the
manufacture
sizing be ?
Any other ideas?


Take 10 meter. Measure the resistance.
resistance is 0.0175 ohm per meter per square millimeter.
From this you can find the area.
Area is 1/4 pi d*d This will give the real copper diameter.

Two prerequisites. Pure copper and the wire is round.



That applies to most copper wire but not these finest dimensions where
that formula breaks down
I'm a machinist and I measure parts that have features smaller than
the wire in question. I use an optical comparator sometimes for these
measurements. The comparator has a large screen that makes these
measurements easy. However, I also have a small hand held comparator
loupe that is used similar to a magnifier. The difference though is
that this comparator has a reticle that touches the item to be
measured. This helps to avoid parallax errors. Mine is made by PEAK
but there are several other brands available. It has a 10x lens in it
and will accurately measure features as small as .025mm.
Link:
http://www.peakoptics.com/index.php?...oducts _id=12
Eric

On Tuesday, August 4, 2009 10:38:19 AM UTC-4, N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?

On 27/09/2013 14:52, wrote:
On Tuesday, August 4, 2009 10:38:19 AM UTC-4, N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?


I do so agree, like minds and all that

On Tuesday, August 4, 2009 7:38:19 AM UTC-7, N_Cook wrote:
Not the first time I've met this problem.
Say nominally about 0.05mm . With a micrometer, how much are you compressing
it? could easily be out by 20 percent out and squaring that if using weight
to length via density or resistance calculation via resistivity, is very
iffy.
If access to a microgram resolution of weighing scales then a few metres of
the wire and density of copper and allowance for enamelling , but no highly
accurate weighing machine. Optically comparing under a microscope needs
known diameter standards.
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, how better accuracy might that be.?
If I start from known good coil of say 46swg enamelled wire and do this 64
wire trick , to work backwards, how accurate/reliable would the manufacture
sizing be ?
Any other ideas?

How about winding the wire onto a piece of 1/16th inch piano wire, do ie; 100 turns and then measure the overall length. Presumed that the wire has no enamel.


My best way.
KW