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Ring around the rosie

#1

Hi,

I don’t usually make custom rings (or any rings). Yesterday, a woman
walked in and fell in love with a hollow ring I designed and made a
while back. (I have most of my workshop trials and tribulations on
display, as conversation pieces.) So, I measured her for a Size 9
and told her I would give her a cost estimate.

Questions:

  1. Is there a chart that indicates the length of metal I would have
    to saw out for a particular ring size? And, should the length be
    exact, or longer/shorter than denoted?

  2. Is there a chart that would enable me to figure out total surface
    weight without actually weighing something? For example, a 1 x 1
    inch of whatever gauge sterling silver always weighs X grams.

  3. Are there any pitfalls I need to avoid when making a ring/hollow
    ring?

  4. On the ring mandrel, do I size the ring on the sizing mark - on
    the top, middle or bottom of the ring?

Thank you very much and keep shining,
Devora

#2 
Is there a chart that indicates the length of metal I would
have to saw out for a particular ring size? And, should the length
be exact, or longer/shorter than denoted?

It’s maths up to a point. Calculate the circumference from the
diameter: it’s a formula. You could make up a spread sheet and show
each size in both dia and circumf.

But you must add a little extra for the physical effects of bending
a strip of metal to a ring shape. People differ in their ways of
calculating this, but a simple way would be to make the ring a
little too small and stretch it up.

Is there a chart that would enable me to figure out total
surface weight without actually weighing something? For example, a
1 x 1 inch of whatever gauge sterling silver always weighs X grams.

It’s also called density and specific gravity. Silver (fine) has a
density of (approx) 10.5 grams per cubic centimetre.

Silver = 10.5 g/cm3
Wax = 1 g/cm3 (approx)

So take a 1" cube of wax and weigh it. That SAME SIZE would weigh
10.5 times in silver.

Are there any pitfalls I need to avoid when making a
ring/hollow ring?

Yes. Make a little hole for the acid pickle to exit out of.

Brian
Auckland NEW ZEALAND

#3

Devora,

  1. On most every ring mandrel I have seen on the back side are a
    bunch of numbers and lines for measuring the blank length. Or just
    use a bit of math… length = inside diameter x 3.14 + metal
    thickness. Both techniques are just approximations but will get you
    close. Aim slightly small and stretch.

  2. Measure in the unit of your choice and compute the volume.
    Multiply by specific gravity.

  3. Size matters. 1/4 of a size can make a lot of difference. Think
    about possible future sizing if possible.

  4. I always use the middle of the ring, seems to save on the concern
    about whether a ring is a narrow or wide band. You still do have to
    decide which width sizer to use when measuring the finger.In a past
    life I used to do lots of sizings with at least a dozen random sales
    people (half+ below average) doing the actual measuring and this
    technique worked best.

Jeff
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand

#4 
Is there a chart that indicates the length of metal I would have to
saw out for a particular ring size? And, should the length be
exact, or longer/shorter than denoted?

Since no one else has mentioned it-- there is a terrific table of
ring blank lengths (along with other useful stuff) available for
download on Ciontenti’s web site for those who would like the math
done for them. http://www.contenti.com/resources

Noel

#5 
It's also called density and specific gravity. Silver (fine) has a
density of (approx) 10.5 grams per cubic centimetre.

During their school careers, my children have often said things like
"I don’t see the point of learning all this maths - I’ll never use
it in real life". But it’s surprised me as an adult just how many
school maths topics are relevant to real life - even some algebra has
been needed at times.

We all learned about density at school and things such as how to
calculate the circumference of a circle and jewellery making brings
such things from the depths of our memories.

Helen
UK

#6

Hi Devora,

Is there a chart that indicates the length of metal I would have to
saw out for a particular ring size" And, should the length be
exact, or longer/shorter than denoted"

Find yourself a copy of Professional Goldsmithing: A Contemporary
Guide to Traditional Jewelry Techniques by Alan Revere ISBN
0-9651049-0-7 There are all kinds of handy charts in the back of the
book, including one on length of ring blanks. If you are in doubt,
cut your blank slightly longer, then saw/ file/sand down to
appropriate size. Buy a copy for your personal library, I think it’s
a must have.

Good luck,
Alexis Romeo
www.alexisromeo.com

#7

Helen you are right ! Jewelry is all about math, spatial
relationships and material science. I LOVE it! I was always a math
and science geek. I took calculus as an elective, because it was
fun. I love the sinusoidal stakes because they remind me of
trigonometric problems. I am reading a book about art and physics
right now and just enthralled.

Susan
www.ThorntonStudioJewelry.com

#8 
Since no one else has mentioned it-- there is a terrific table of
ring blank lengths (along with other useful stuff)

There are threads that I could post but don’t, thinking others can
have their say.

Since no one else mentioned it — Both Metal Techniques for
Craftsmen and Concepts and technology have a wealth of charts in the
back - speaking of Oppi. I think there’s ring sizes, but I’ve often
gone to the table of weights/sq. measure of metals…

http://www.donivanandmaggiora.com

#9

Hi Susan,

I love the sinusoidal stakes because they remind me of
trigonometric problems.

Mm, need to get me one of those!

I am reading a book about art and physics right now and just
enthralled.

Wow, that sounds interesting! I wonder whether it will take you off
on some new design ideas - how exciting! When I was doing a garden
design course, I drew a lot of my inspiration from my science degree
days and a lot of my designs were derived from things such as the
double helix of DNA, or spirals found in nature, etc. I love the
whole idea of making some jewellery inspired by molecular models too

  • oops, maybe I shouldn’t shout about such things.

Helen
UK
http://www.hillsgems.co.uk

#10

I have a client, an artist who rediscovered higher math in her
middle age. She has integrated her love of mathematics into her art,
and she has designed and commissioned me to make several pieces based
on mathematical models. Very interesting stuff, and not at all the
sort of thing I would ordinarily think of-- I’m a biology person.

Janet Kofoed
http://users.rcn.com/kkofoed

#11

Hi,

I want to express my appreciation for all who kindly responded to my
ring questions. Thanx to all of you, I now can proceed. well armed
with all the book titles and links I need.

Thank you again and keep shining,
Devora