Back to Ganoksin | FAQ | Contact

Sizing math


#1

I want to make some bangle bracelets, and a cuff bracelet.
Construction is fairly easy, especially if you have patterned wire.

My problem is this: I have large hands and wrist. wrist is 8 3/4"
Now if I use double half round wire, and saw between that double wire
in the center and pull it open some, I’d be losing some of the
length, right? I figure there should be a 1 1/2" open space on the
back of the cuff. Does that mean I should start with a 7 1/4" peice
of wire?

On the bangle, I have one that fits. The diameter is 3". So if I
multiply 3" by pi 3.16. that would round off to 9 1/2" I get
confused because if I carefully measure the inside of the bracelet,
and then the outside, I get two different measurements.

Now I know most of you are way beyond this problem. But it’s making
me nuts. Am I missing something so easy, that I’m gona look stupid?

Any help would be appreciated.
Life is good.


#2

Hello! Figure out the length of your wrist, sounds like you have.
Then measure the thickness of your stock, be it .040 inches (1mm
give or take) or thicker/thinner. Add the thickness of the stock
TWICE to your wrist measurement, then multiply by PI. This will give
you outer circumference which is what you are looking for.

Hope this helps!
Mary Linford
Blue Star Wax Carving


#3
On the bangle, I have one that fits.  The diameter is 3".  So if I
multiply 3" by pi  3.16. that would round off to 9 1/2"  

I think you got your PI wrong :slight_smile: you should use pi=3.14159, which is
pretty good, or… pi=3.14159265358979323846

hth
Hanuman


#4
I  get confused because if I carefully measure the inside of the 
bracelet, and then the outside, I get two different  measurements. 

The outside is going to measure longer because there is more surface
due to a greater distance from one side to the other on a curve. In
the back of Alan Revere’s Professional Goldsmithing there are
numerous calculations that are wonderful to have which include the
size of a blank depending on the thickness of the metal. Although
you calculated by multiplying times pi, you need to take into
consideration the thickness also. So, add the thickness of your
bracelet to the length desired then multiply times pi.

Marta in Georgetown, CA


#5

Another good old book for calculation charts is by Oppi Untrach
(SP). Mine is in tatters from use. It also has just about every
technique known to man except for Guilloche enamel. There is no
mention of engine turning

Robert