I need to make a size 8 rolling ring but I forgot what size to make
each of the 3 rings to come out as a size 8 when joined. Also not
sure how they interlock. I made one using size 9 rings but it was too
small. Any advice you can give would be greatly appreciated.
As a first approximation, the internal diameter of each ring is
equal to the internal diameter of the required ring, plus the
thickness of the metal used.
A size 8 has an internal diameter of 0.71". If the thickness of the
metal is.07" (you can figure the gauge - I use real measurements)
then the internal diam eter of each ring is 0.71+.07 = 0.78", which
is about size 10. Because the internal shape of a rolling ring on the
finger is a rounded triangle rather than a circle, and because they
don’t really slide on and off the finger, you can afford to make
them a little smaller than you would for a solid ring of similar
width.
Link the second ring on the first one, and the third one through
both. You can’t do it wrong.
You will need a ring mandrel with a groove in order to make each
ring round after soldering, and, with care, it’s possible enlarge
each ring a little with a roller-type ring stretcher.
Regards, Gary Wooding
It does depend on the the thickness of the bands, I remember about 1
1/2 sizes larger for 1.5 mm half rd wire, about 3mm wide.
If the target size is 8, shoot for a little under size 10 1/2 for
each individual ring. This is my protocol for 8 gauge half round.
Also be aware that a size 8 rolling ring will often fit more loosely
than a solid band size 8, due to the sliding nature of the rings.
Make sure you have a mandrel with one side ground off so you can
hammer round the last two bands without goobering up the preivious
bands.
Dale
The Silver Forge
What is rolling ring? Can someone Show me a picture. Thanks.
I presume that by “rolling ring”, you mean a russion or trinity band
of three 3 rings. I’ve been considering this problem myself recently
- I wish I had an answer, but I do have some thoughts on creating a
graph the will eventually provide the answer. The variables for this
problem aRe:* Thesection of the rings (eg. D, court, round)* The
width of the rings (eg. 2. 3mm)* The depth of the rings (eg. 1. 5mm)*
The finger size of the rings before linking* The finger size of the
rings after linking Thefinger size after linking is the answer we
are looking for, so we don’t need to plot that on the graph. The
section of the ring will usually be D-section, but if other sections
were needed, they would each need their own graph - if nothing else,
I suspect that the way the three bands interact would be different
depending on the section. So, we’re left with three variables to plot - width, depth and unlinked ring size. Mathematically, this is very
easy to plot - a normal XYZ graph would do; the problem is that it
isn’t very easy to look at, particularly once all possible points are
filled in. I had hoped to use a “triangular graph”, which uses the
three sides of the triangle as the three axes, but it turns out that
it can only be used in situations where the third variable is a
result of the first two the you input. My hope was to use trial and
error to plot the first few points on the graph, and then use that to
work out the rest of the datapoints - as time went by, experiments
and production pieces could be used to test the accuracy of that and
then adjust it. Each datapoint would need to appear as a finger size,
allowing the jeweller to cross-reference the known variables of the
job (width and depth) with the linked and unlinked ring sizes.
(Thinking about it, it might be better if the three axes listed the
width, depth and linked ring size, because I suppose that they are
the real “known” variables, and the unlinked ring size is the one
that we don’t have). I have two questions of my own for the
orchidians - does anyone know a suitable type of graph or table for
plotting this and does anyone know if this work has
been done by someone else (either available for free, or by
purchasing a book?). I would expect that this does exist,
because there are plenty of large companies that do production runs
of these kind of rings.
Jamie Hall - who is not scientific enough to be a scientist, but too
scientific to be a normal jeweller 
http://primitive. ganoksin. com
I just tried an experiment.
I built a 3D model of a rolling ring in TurboCad. Each ring was made
from 1.5x4mm D section material with an ID of 18mm. The centre hole
(where the finger goes) is in the shape of a rounded triangle, but
the central section bulges out, rather like a rounded triangular
barrel. Measuring the outsides of the hole, the largest circle that
can be drawn inside the triangle is 13.6mm diam, but the circle that
just touches the corners is 17.5mm.
As mentioned already, the axial section of the finger hole doesn’t
have straight sides; they bulge outwards, so that the hole is bigger
on the absolute centre of the ring than at the extremities. Because
the rings slide over each other (rather like caterpillar tracks),
they don’t have to slide onto the ringer, so the assumption that the
size of the final ring is about the size of the individual rings
minus the thickness of the metal is a pretty good approximation.
IHTH
Regards, Gary Wooding
OK, lets make this a lot easier. Once you’ve made one band and
written down its length (to the 1/10 mm) before soldering and
hammering it round, you’ve got the rule for all sizes. Just add
2.5mm for a full size bump, 1.25mm for half size increments. The
thickness of the material is not a consideration, as it is the length
of the flat piece which counts - it will be the internal radius - the
outer circumference will stretch out over than mandrel when forming
the ring. This rule is for SS - 14K, yellow and white, do not stretch
as much over the mandrel; adjust lenght upwards. But the 2.5mm rule
per size still holds.
DALE - The Silver Forge