Hi, I am just starting out on my jewellery career and I recently made

a Russian wedding ring (normally three different coloured gold bands

linked together) from which I read the instructions in a book. The

problem is that although I followed the sizing rules in the book, it

turned out no where near the size I had expected. Can someone please

let me know how I calculate the length of rod needed if for example

the ring circumference is 66mm what length do I have to cut the (half

round rod) if it is 3mm thick

Thanks in advance for your help

It’s a bit more complicated than that. Since the rings roll over each

other, each band needs to be larger than the actual ring size, on an

American ring gauge, and using 3mm x 1.5 mm thick half round stock, I

have found that the size difference is about 1 1/2 sizes larger. That

would be about an extra 4.6mm or so.

Hope this helps

Rick Hamilton

Dear Paul, First figure the diameter which is: circumference / pi: (66

mm / 3.14 = 21.02) Then length needed will be (diameter + thickness) x

pi. (21.02 mm+ 3 mm) x 3.14 = 75.42. For bands over 4 mm in width

generally add 0.5 mm to length.

Alan Revere’s Professional Goldsmithing book has a great chart for

cutting lengths from size 1 to 14 in thickness’ from 0.8 to 2.6

calculated out along with lots of other useful

Best regards,

Marta

paul - someone has probably already answered this, but i mark off the

mm measurement onto a 1/4 inch wide strip of cardboard or magazine

insert, cut it at the mark, tape it & slip it onto my ring mandrel

for the standardized ring size, which has sizes broken into 1/4s.

from then on i work on the mandrel at that size. for customers

sending their ring finger measurement by mail i have them cut a 1/4

inch wide strip from an old business card or a torn-out magazine

insert, roll it up once, wrap it around the largest knuckle on the

proper finger so that there are 2 thickness on top & stick a pin

through both. they then send that to me; the vagaries & inaccuracies

of measuring rulers or tapes that people have on hand, misremembered

sizes, etc., are all eliminated by this method that treats the length

as a cipher rather than a possibly inaccurate measurement.

good luck -

ive

Dear Tom, I have much success calculating the blank this way. I check

the size of the ring. Than I measure my ring mandrel at a half size

smaller than the ring has to be. Take that measurement and add the

metal thickness. Once I get that answer I multiply it by 3.1416

(pi). That’s the length of the ring blank. I like to stretch it up

on a ring stretcher to make it nice and round. It makes it nice and

hard too. Another benny is I don’t have to use as much metal.

However slight. It adds up over time. Example: 16mm (diameter for a

size 6)+ 2mm(standard thickness for a wedding band)3D 18 x 3.1416 3D

56.5488. Round it up to 56.55. Now if I want to make something like a

bezel with a seat I would do the same thing measure the stone add the

metal thickness and multiply by 3.1416. To make the seat fit in the

bezel I already know the diameter of the stone so I would take the

stone size subtract the metal thickness and multiply by 3.1416. It’s

always good to be a little short because the metal stretches when I

tap it on the mandrel. Sterling silver is the hardest to calculate

because it stretches so much. Good luck, Hope this helps, Johnny I