I am a rank beginner, who is loving learning the basics in night
class. I have set up a bench and some basic tools in my spare
bedroom, and want to practice at home, making / finishing items I
have kicked off in class. Last term I made a forged square men’s
wedder (in silver), and want to make another as a gift for a family
member, which leads me to a couple of questions…
is there benefit in forging (hammering up to size and shape on a
ring mandrel, then filing to refine the square shape) v/s carving in
wax and (sending out for) casting?
if forging, then:
2a) how many sizes down from finished size should I start at, Ie: if
I want to forge up to ring size Q (8 1/4), do I start at, say… N
(6 3/4) or smaller / larger?
2b) If I want the finished width of the band to be approx 6mm
(0.24") wide, and thick enough to provide for the filing and
shaping, how do I figure out what thickness / length silver bar I
should start with to get there?
The difference between forging and casting (and this usually leads
to heated debate on this list, so heads up), castings are in an
annealed state after being cast, hand forged rings are work hardened.
The casting will be softer, the hand forged ring will be more
durable.
Appearance wise, they can look pretty much the same, and both can
hold stones.
To work out the the length of metal you would need for a ring would
be :-
Pi x median diameter = length of metal
median diameter = inside diameter of the ring plus one metal
thickness
The difference between forging and casting (and this usually leads
to heated debate on this list, so heads up), castings are in an
annealed state after being cast, hand forged rings are work
hardened. The casting will be softer, the hand forged ring will be
more durable.
Castings are not in annealed state, they are in the “as cast” state
which is quite different in so far as the crystal structure is
concerned. As cast crystals are typically larger than wrought, work
hardened or annealed wrought metal. As cast items can be either
harder or or softer than the annealed state depending on factors
like cooling rate and alloy composition. There is a phenomena called
coring that is not unusual in alloy castings. As the molten metal
begins to solidify the chemical composition of the dendrite arms of
the crystals will vary from the inside to the outside of the arm. So
the composition of the alloy is non uniform this can result in the
casting having different properties than a similar alloy that has
been hot or cold worked and annealed.
As always, James Binnion, I so very much appreciate your clear,
uncomplicated and direct insight (into so many technical matters
that see the light of day within this wonderful forum), time and
time again. Thank you, once again, for cutting to the chase without
any of the need-less (and extremely boring) egocentric coloration
which so often appears in several other “main stay” respondent’s
offerings which we read (almost daily) in these Orchid postings.
Very grateful for your consistent, knowledgeable clarity over these
years,
I am dumfounded that anyone should want to cast simple shaped items.
Even if you have to order a piece of square wire or bar, bend it
around a mandril, saw it, solder it, size it and polish it. Surely
you will have a beautiful hand made piece of jewellery. I could do
it in all10 minuits, and have a happy customer. And reusable scrap.
Against: preparing a perfect wax, (10 minuits on a lathe) sending it
to the caster, waiting days, having to file off the outer surface,
check for porosity, repair any porosity, check the size, polish and
pay for the casting. Probably doubling the cost price in silver. Dont
reuse casting silver scrap! Practically always, it is easier, quicker
to handmake simple shapes. I always invested in the best tools I
needed, drawplates, etc. when I was starting out. They soon paid for
themselves. Casting for complex shapes, when you know you will be
making many.
David Cruickshank (Australia)
jewellerydavidcruickshank.com.au
That reminds me I have to pop down to JTB and get a square draw
plate.
I’m sort of leaning towards getting precision components cast, sure
I could cut gears by hand, but I don’t have much time this year and
it has to be precise. I’ll still cast sculptural pieces.
The simple stuff is easy enough to make, although casting is good
for volume.