Drawing half-round wire from round

Jewelry Discussion
1

OK, I have ascertained that Stuller doesn’t carry the Argentium
silver in half-round, and I need some half-round for some of my
projects.

So I’m going to have to draw it, which is no big deal except I can’t
remember how to draw half-round from round other than by soldering
together two pieces of round wire and drawing it that way. Which I
don’t want to do because of the issues of solder tarnish. It would
be a shame to have my lovely virtually untarnishable Argentium work
of art (yeah right!) streaked with solder tarnish at odd spots along
the length of the wire…

So can anyone tell me how to draw half-round wire from a single
piece of round wire? Like what size to start with in the round wire
to get the desired size in the half round…

Ditto for square wire from round wire, for that matter.

Thanks.
Sojourner

2

Drawing the round wire square is simple enough, provided your
starting gauge allows for enough reduction by the time it becomes
square. It might take 6 to 8 dies, depending upon your drawplate.

To make the half round stock from round wire it is easiest if you
roll the round wire slightly flat first. This reduces the amount of
drawing that will be needed to pull it down to half round. If you
fold the wire in half you will only need to solder the tips together
and file the end to a taper, then begin pulling. (This is assuming
that you are using a round drawplate to produce half round wire.)

Michael David Sturlin
www.michaeldavidsturlin.com

3 
    So I'm going to have to draw it, which is no big deal except I
can't remember how to draw half-round from round other than by
soldering together two pieces of round wire and drawing it that
way.  Which I don't want to do because of the issues of solder
tarnish.  It would be a shame to have my lovely virtually
untarnishable Argentium work of art (yeah right!) streaked with
solder tarnish at odd spots along the length of the wire....

You only need to solder the first half inch, or so, of the wires
together. Enough to form the taper that is held in the pliers.
Chances are that the two wires will twist as they go through the
draw plate, so it is a good idea to use a vane made from thin metal
to guide the wires into the plate.

    So can anyone tell me how to draw half-round wire from a
single piece of round wire?  Like what size to start with in the
round wire to get the desired size in the half round... Ditto for
square wire from round wire, for that matter.

'cors you could just buy half round or square draw
plates…

Bill Bedford

4

The wire only needs to be soldered at the pointed end. No other
solder. I don’t do Argentium, but when I need gold half round wire,
I simply fuse the ends of a single piece of flattened wire and roll
a point onto that end.

5 
    You only need to solder the first half inch, or so, of the
wires together. Enough to form the taper that is held in the
pliers.

Yeah, that’s how you do it with two pieces of square wire, and I see
how that works, because you have a flat edge to flat edge that ends
up being the inside, flate edge of the half-round wire, and the outer
square edges of both pieces get rounded off as you pull the two
pieces through a single round drawplate hole.

However, I’ve seen instructions that say to solder together two
pieces of ROUND wire for their entire length, and then pull that
through a half-round drawplate. THAT I don’t see how it would work,
and it would seem that even if it did, you’d have exposed solder
joints at some spots along the length of the drawn wire.

 So can anyone tell me how to draw half-round wire from a single
piece of round wire?  Like what size to start with in the round
wire to get the desired size in the half round... Ditto for square
wire from round wire, for that matter. 

        'cors you could just buy half round or square draw
plates................

Well, yes, I could, and have. I guess I was hoping for some rules
of thumb about what size of round wire to start with to end up with a
particular size in the half-round or square wire that you’re
drawing. I’m sort of limited, budgetwise, and I can’t really afford
to buy each and every gauge of Argentium sterling and experiment if
there’s the possiblity of narrowing my choices down to fewer sizes.

Sojourner

6

Hi Zen,

I guess I was hoping for some rules of thumb about what size of
round wire to start with to end up with a particular size in the
half round or square wire that you're drawing. I'm sort of limited,
budget wise, and I can't really afford to buy each and every gauge
of Argentium sterling and experiment if there's the possibility of
narrowing my choices down to fewer sizes.

Here’s where you high school geometry class will come in handy.

To see what size round wire it takes to make a given size of 1/2
round calculate the diameter of the 1/2 round. (It helps to have a
calculator with a ‘pi’ key on it.)

The dimension of the flat side of 1/2 round wire is listed as the
same dimension as the diameter of round wire e.g. 16 ga round is
.051" in diameter, 16 ga 1/2 round is .051 across the flat. A line
from any point on the outer edge to the center point of the flat
side is .0255".

To find the area of 16 ga 1/2 round, find the area of a 16 ga round
wire, then divide that number by 2 for 1/2 the area.

Area = pi r squared (r = radius of the circle (wire))

A = pi (3.14) x .0255 squared (.0255 x .0255=.00065025) =
.002042821 sq. in.

16 ga round wire has a cross sectional area of .002042821 sq. in.

16 ga 1/2 round has a cross sectional area of .002042821 sq. in.
divided by 2 = .0010214105 sq. in (round to .001021410).

Now it’s necessary to see what size round wire has a cross sectional
are of .001021410 sq. in.

To do this the same formulae are used.

A = pi r squared (r = radius )

.0010214105 sq. in = 3.14 x r squared

Since we already have the Area, we need to divide the area by pi
(.001021410 sq. in divided by 3.14 = .000325125)

r squared = .000325125

r = square root of .000325125 = .01803122 inches

diameter = 2r ( 2 x. .01803122 inches) = .03606244 inches

Now it’s a matter of looking at the wire gauge or a table of wire
gauge dimensions & finding a wire that has a diameter of .03606244
inches or a little more. In this case, 18 ga which has a diameter of
.040".

Soldering about 25 to 35 mm (1 -1 12/") of the end of 2, 18 ga
round wires together & drawing them through a drawplate with round
holes will provide 2, 16 ga 1/2 round wires.

Using 2, 18 ga round wires drawn into 2, 16 ga 1/2 round wire will
result in the 1/2 round wires being approximately 23% longer than
the 18 ga wires drawn.

This can be found by dividing the area of the larger (18 round)
diameter wire by the area of the smaller (16 1/2 round).

area of 18 ga round .040 (diameter of 18 ga) divide by 2 = .020
(radius of 18 ga) A = pi x r squared (3.14 x .0004) = .001256637
sq. in.

.001256637 divide by .001021410 = 1.230296415

This same methodology can be applied when converting any shape &
size wire to any other shape & size. Just use the mathematical
formulae for calculating the area of geometric shape of a cross
section of the wire.

Additionally, it can be used to determine how much of a larger wire
to draw to produce a given length of smaller diameter wire.

Dave

7

If you solder the entire length of two wires together, square or
round, you’d have to saw them lengthwise to get two half round
wires. Might as well just saw some round wire to begin with.

Solder just the ends together, file, draw, separate, enjoy.

James in SoFl

8 
    However, I've seen instructions that say to solder together
two pieces of ROUND wire for their entire length, and then pull
that through a half-round drawplate.  THAT I don't see how it would
work, and it would seem that even if it did, you'd have exposed
solder joints at some spots along the length of the drawn wire.

Well – you flatten the ends of the wire where they are going to be
soldered together. So that not only do you get a good joint, but the
section of the ‘tail’ will match the shape of the holes in the draw
plate and so be that much stronger.

There is a subtle difference between half round wires drawn from
round and square wires. If you start with square wire the angles
where the flat meets the curve of the wire will be sharp while if
you start with round wire there will a small radius there. If you
intend to solder the wire onto sheet the the wire with slightly
rounded corners will look better because the solder will form a
meniscus in that radius and so give you a sharper looking join. The
sharper edged wire on the other hand will tend to blend into the
backing sheet.

Bill Bedford