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Bench tips - stock length for band rings and bezels


#1

All round things can be made with this formula:

(Diameter + stock thickness) x 3.14 is exactly the length of stock to
cut.

It works for rings, and equally well for bezels. If you are doing
oval bezels, find the average diameter 3D ( Length + width)/2 and use
the same formula.

Geometry is wonderful.

Judy Hoch, BA Mathmatics, now a jeweler and metalsmith, and having
more fun.


#2
    (Diameter + stock thickness) x 3.14 is exactly the length of
stock to cut. 

Hi all:

Since we are on the subject of stock length for ring sizes I have a
question. If a ring were designed as follows how would you calculate
size?

  _____ (bezel)
   |___| (ring shank)

The best I could do without a picture. Imagine the top is the bezel.
The shank of the ring would be half round. The shank is soldered to
the bezel from underneath. Now my question is how does one determine
ring size. It seems to me that due to the flat bezel and the half
round shank the 3.14 calculation does not work in this instance. I
have looked for a calculation for this style of ring but I have been
unable to find it. Any suggestions?

Linda Crawford
Linda Crawford Designs
Willits, CA
http://www.lindacrawforddesigns.com
"Experience is something you don’t get until just after you need it."


#3

Hi Linda Crawford. I make a lot of rings like you described and I
ultimately rely on the “finger test”. I find one of my fingers or
knuckles that is as close as possible to the ring size I took from the
client and simply fit the ring to that finger or knuckle on my own
hand. Hope this helps, Kind regards, Rex from Oz


#4

I have made several rings of the design which you describe. The way
in which I guage the length of the ring shank is as follows:

First, I make the bezel, which i place on a ring mandrel at the
desired ring size. Then, I take a piece of scrap wire (copper wire or
even garbage bag ties,) fit it to the bezel on the mandrel and cut it
off at the appropriate length. Finally, I straighten the scrap wire
and use it as my guage for the length of the shank. Simple, easy, and
no math skills required.

Lee Einer


#5

Linda,

If I understand your question, there are two solutions I can think
of. In each case the formula works. Using the formula, calculate the
proper length and while the shank is still flat, cut a hole into which
the bezel will fit. Round the shank and trim the hole for a close fit
of the bezel, insert the bezel so that the right and leftsides are
even with the inside of the shank. This will leave the center part of
the bezel extending below the shank inner surface. Solder and trim
flush the bezel to the inside the shank.

The other way is to round the shank and cut a curved bottom to he
bezel so that it fits the contour of the shank and solder on. This
of course leaves a closed bottom to the bezel and is more difficult to
do than the first option .

Jerry in Kodiak


#6
   Since we are on the subject of stock length for ring sizes I
have a question.  If a ring were designed as follows how would you
calculate size? 
_____ (bezel)
 |___| (ring shank)

If I’m correct you would not like to make your shank half round but
D-shaped.

In that case the correct formula would be: (3.14 times 0.5 times
diameter) + diameter + stock thickness of shank (to compensate for
the bending). It cooks down to 2,57 times diameter + stock thickness.

And thanks, Hanuman et al, for your comments on the spelling. I hope
it goes a bit for the grammar as well, as it helps us who have not
English as our mother tongue, think in another language and have to
translate that into a foreign language.

Kind regards
Niels Lovschal, Jyllinge, Denmark
@L_F8vschal
phone (+45) 46 78 89 94


#7
     If I'm correct you would not like to make your shank half
round but D-shaped. In that case the correct formula would be: (3.14
times 0.5 times diameter) + diameter + stock thickness of shank (to
compensate for the bending). It cooks down to 2,57 times diameter +
stock thickness. 

Hmmm? I think we may need a clarification here.

I worked through Niels’ formula and realized that he’s envisioning a
true D-shape, where the upper shank forms a straight, horizontal base
for soldering the bezel to it. In which case, his formula is
correct.

If we’re talking a true half-round shank, with the bezel itself
(e.g., bezel cup) taking the place of the upper shank in Niels’
vision, the formula would be: (3.14 times 0.5 times diameter) + stock
thickness of shank – though I’m not sure whether a full thickness of
a shank would be needed.

But, in both the above, you’d end up with gaps between the finger and
the shank in the upper corners – not a problem if that’s part of
your design. As usual, I was thinking of something totally different
still – more of a C-shape. In which case, I think the easiest route
is making a full shank and filing/grinding/cutting/milling a flat for
the bezel to mount to.

So, which is it? :slight_smile:
Warm Regards,
Shawn


#8
Hmmm?  I think we may need a clarification here.

Shawn, Well, at first I thought I wanted half round. Of course, the
picture I used was most defiantly a rough and if you use your
imagination it is really rounded on the bottom. So since I have a
lack of experience in the alphabet soup of ring shanks I said half
round which I originally did mean. But, what I really want is a more
accurate way to measure when including a bezel, on a C shape, D shape
or any other part of the alphabet I don’t know about. I have been
using the formula for a round ring size and then I have been
subtracting the size of the bezel in mm and have ended up with a ring
smaller than my original intent. I believe it is due to the flat
bottom of the bezel.

I will use the following as an example of what I am currently doing:
Ring size 7 , 2 mm thick and is larger than 4 mm with a bezel that is
15 mm in diameter.

My calculations would be as follows:

3.14 x 2.0 = 6.28 or 6.3 + 54 + .05 for a size 7 ring and would equal
60.35.

Now my dilemma I have a bezel that is 15 mm in diameter and if I
subtract it from the 60.35 I end up with a ring smaller than a size 7.
I apologize if I was not clear on this earlier and I hope this isn’t
more confusing. Thanks for the help.

Sincerely,
Dazed and Confused at the Bench
Linda Crawford
Linda Crawford Designs
Willits, CA
http://www.lindacrawforddesigns.com
"Experience is something you don’t get until just after you need it."


#9

Linda When I make a ring like this I balance the bezel on my triblet
at the right position for the size I want and use a piece of binding
wire (or anything else handy to be honest) to wrap round the triblet
and but up to the back of the bezel. A snip and check gives me a
template to cut the shank to length. After bending to half round the
size can be checked before final filing to truethe ends and soldering
to bezel. If you haven’t got a sizing triblet find the right place
with a ring gauge and mark it with masking tape just up from the size
needed. Andy Parker, Agate House Lapidary Ulverston, Cumbria, England
@Andy_Parker www.agatehouse.co.uk Tel: 01229 584023


#10
Linda When I make a ring like this I balance the bezel on my triblet

Andy,

I am going to assume that a “triblet” is the same as a ring mandrel.
Am I correct in that assumption?

Again, I want to thank everyone who has provided on this
subject.

Linda Crawford
Linda Crawford Designs
Willits, CA
http://www.lindacrawforddesigns.com
"Experience is something you don’t get until just after you need it."