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Hollow Core Bracelet


#1

I have been commissioned to make a gold, hollow core, hinged
bracelet (very similar to those seen at department stores). I
think I have a handle on the hinge and clasp, but I am at a loss
as to how proceed with fabriacting the hollow core body. How is
this type of stuff done? Thanks - Steve

Steve Wiser
PO Box 938
Santa Margarita, CA 93453
(805) 438-5232


#2

One way to fabricate a hollow bracelet with or with out the
hinge and clasp is by anticlastic forming. This done by forming
sheet metal in opposing curves. Heppa Sepka (I’ve probably
mispelled his name) did a lot with this in the 70’s. He wrote a
book which would explaine a lot if you can find it. Marilyn Smith


#3

<< how proceed with fabriacting the hollow core body >>

You might look at some of the work of Michael Anthony He uses
hollow forms a lot in his work. He has had pieces pictured on the
front and back covers of Metalsmith Magazine many times. My
experience to date is to shape sheet with a chasing hammer and
then fill it with pitch to give the unit a solid cor while
forming. As the metal work hardens remove the pitch, anneal,
refill with pitch. Continue just as you would with any hollowware
piece. It is a VERY long drawn out process. Someone else out
there in happy jeweler land might have a better Idea though.
Later Red


#4

Hi Steve, There are a couple of useful prinicples. One is that it
is easiest to shape a sheet metal bracelet from a complete band,
that is that you solder a band of sheet metal and then shape it.
When you are done shaping m,ake your cuts. Then ‘deck’ it, that
is solder a band into the interior while it is whole. Perhaps
start a cut to let the air out at one spot. Shaping can be done
by sinking the middle of the band outwards into wood by
appropriate hammer blows or raising the edges of the sheet down
over a rounded tool (like a dapping punch held in a vise). In
both cases the apparent circumference of the bracelet will be
reduced so you need to plan for this in your initial band length.
good luck.

Charles

Brain Press
Box 1624, Ste M, Calgary, Alberta, T2P 2L7, Canada
Tel: 403-263-3955 Fax: 403-283-9053 Email: @Charles_Lewton-Brain

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#5

Hi Steve

Charles’ suggestions are right on the money as usual. I’ve
always avoided hand making domed bangles because you can buy them
so inexpensively, and the work entailed in making one is so
extreme.

I believe the process used by the manufacturers is somewhat
automated, using large and heavy forming equipment. The nicer
hinged hollow bangles even have a formed inner sleeve, comfort fit
as it were.

The main problem I’ve encountered in forming objects like this is
comformity of curve. To smooth out all the bumps and other
irregularities and form an extremely evenly curved oval domed band
can be excruciating. If you had access to a hydraulic press such
as that from BonneyDoone Engineering, the project would be
simplified. There are attachments designed for work of this sort.
However, you might need to make some of your own forming tools to
generate the oval rather than a round bangle.

To add to your miseries, you may also encounter warpage as you
solder, pulling the seams apart, or twisting the edges. The
warping can be avoided by frequent annealing during and after the
forming process.

I wonder if the bracelet could be made by an electroforming
process? You’d need to make a core. There might be a company that
would do this for you, anyone have any suggestions? All you’d need
to do then is make your cuts and install the hinge and clasp.
Hmmm… I’ll do a search… Maybe the MJSA can advise us here…
I’m getting some ideas… hmmm :slight_smile:

And of course, anti-clastic raising as mentioned earlier by
Marilyn Smith is an alternative. Ettienne in Maine (I forget the
artists name) produces exceptional hollow forms. I’ve had the
opportunity to work with some of his creations, amazing jewelry!
Once again, the difficulty I perceive with this technique lies in
achieving a perfectly regular surface and oval curve. I believe it
could be done, but might require extensive experience with the
process. I’ve never tried it, so you can take my advice here with
a grain of salt.

Good luck, making a hollow domed, oval, hinged bangle bracelet
would be a valuable learning experience.

Jeffrey Everett


#6

In a message dated 97-04-02 09:52:28 EST, you write:

< And of course, anti-clastic raising as mentioned earlier by
< Marilyn Smith is an alternative. Ettienne in Maine (I forget
< the artists name) produces exceptional hollow forms. I’ve had
< the opportunity to work with some of his creations, amazing
< jewelry!

Michael Good is the Anticlastic Guru.


#7

Marylin, Heikki Seppa’s book is entitled “Form Emphasis for
Metalsmiths” Metalsmth


#8

I’ve had some luck making hollow core pieces from commercially
availabe tubing, using a tightly coiled spring as a removable
core.


#9

If the body of the bracelet is a simple tube in shape, why not
buy a straight piece of tubing from a refiner and anneal and bend
it using a tightly coiled steel spring as a removable core? If
you are making the bracelet in two hinged pieces, you should only
have to bend each piece 180 degrees, making removal of the spring
fairly easy. to avoid ‘bumps’ in the bend, use a piece of thin
copper sheet wrapped around the spring. I have done this to make
parts before, and found it necessary to stop and anneal several
times to produce an even bend, working the piece cold. Metalsmth


#10

That’s twice I’ve heard of “anti-clastic” raising. Jeffery
Everett mentioned it in reference to the work of Ettiene in
maine. I was in Ettiene’s store in Camden on monday and would
love to learn how to form metal like they do. Amazing stuff! Are
there any reference books on this technique? I formed some
interesting shapes by drawing some silver strips through a 1/2"
thick plastic drawplate and produced some beautiful spirals with
the U-shaped silver but have no idea how to form the loops etc.
dave

\o/
O “Help! I’m being held captive by aliens on a comet!”
/ \


#11

A year or so ago, I cast a hollow bangle. What I did is carve a
solid bangle from wax, split it and hollowed out both halves.
Inside half and outside half. I then reassembled both halves
forming a hollow wax model. Next for easier handling I cut the
bracelet in half where the hinge and catch belong. This gave
each bracelet easy access for investment through the ends. I
drilled a few holes through the model halves and ran gold wires
through with the wires extending about 5 - 6 mm extending outside
the models. These wires provided support for investment during
casting.

I’ll leave the rest to you imagination. It took two tries, but
in the end I delivered a pretty good product. It was, I believe a
lot easier than trying to raise two halves and soldering them
together.

Only question in my mind is how someone could accept a
commission to do a job he doesn’t know how to do. How does one
come up with an estimate this way?

Bruce D. Holmgrain
E-mail: Manmountaindense@Knight-Hub.com
WWW: http://www.knight-hub.com/manmtndense/bhh3.htm
Snail Mail: POB 7972, McLean, VA 22106


#12

Dave,

Michael Good is the expert on this form of shaping. I have not
tried it yet because, if I understand the process, you need some
specially made anvils and I that’s just not in our budget yet. I
do love the form of pieces made by this process. There are
occasionally workshops conducted on the how-to of anti-clastic
raising but I haven’t heard of any in New England lately. If I
catch wind of any I’ll post it.


#13

There is a good description of anticlastic raising by Michael Good in the
book Metals Technic published by Brynmorgen Press, 1992. The article
contains many clear illustrations and easy to understand text, including
descriptions and diagrams of the simple tools you need. For a more complete
description, Michael recommends Form Emphasis for Metalsmiths by Heikki
Seppa, published by Kent State University Press, 1978. Business is slow
right now and this looks like fun, hmmm…


#14

You can make your own stakes from hard wood. An eighteen inch lenght of
dowel is easy to find and is a good place to start. Simply file various
sized curves into it. There only need be an inch or so space betwene the
depressions.Sand as smooth as possible. The shapes and their angles really
do not need to be specific. The metal is not shaped over or into a hole
shape. The metal is moved over a rather small area of any one stake and
that is the spot that the hammer is hitting. It is not like putting a slab
of clay into a drape mold.The hand that holds the metal, controls the
resultant shape.It takes some practice but gives good results. Metal
stakes can also be made into serpetine shapes using a forge or oxy acty
torch and tapered rods such as drift pins. Marilyn Smith


#15

Thank you, Marilyn!!

I’ve been wanting to try some raising like this but never thought of
making stakes from hardwood. The first stakes I saw/used were metal and I
guess I just developed a mindset, forgetting about wood.

Sharon.


#16

Michael Good is the expert on this form of shaping. I have not
tried it yet because, if I understand the process, you need some
specially made anvils and I that’s just not in our budget yet.

You won’t get those anvils commercially, but have to make them yourself.
The good news: you can make them from (hard-)wood or suitable plastics.


#17

< The first stakes I saw/used were metal and I
< guess I just developed a mindset, forgetting about wood.

Hi, Do dot forget delrun plastic for use as a stake. It can be shaped with
most tools and will not dent the item being raised as easily as wood oe
metal. It is the same material as is used in the popular plastic mallets
in the jewelry supply catalougs. It can be ordered in almost any shape or
thickness from United Plastics Corp.1 800 537 9724

RED


#18

Hi Steve, There is a whole book on the subject, regrettably only available
in German, by Gottfried Stepan, Armreifen, published by
Ruhle-Diebener-Verlag GmbH & Co. KG, Postfach 70 04 50, D-70574 Stuttgart,
Germany. It’s extensively written by an old master goldsmith from Vienna
who had specialised in making boxes, etuis and bracelets. I have only
limited experience in fabricating hollow bracelets out of round diameter
tube. After drawing and soldering (or buying custom made seamless tube,
wich isn’t too expensive here) I wrap up one end like a toothpaste tube,
filling it with very fine sand (some stamping is necessary to avoid any
trapped air) and then closing the other end. There should be no voids not
filled with sands. You now can bend the tube around a former (a turned
wooden or plastic disc and a thick dowel mounted to a board, distance
about thickness of tube). Tube should be at least 4" longer than needed
for the bracelet, as you need something to grip and the very ends cannot
be bent. Hope this will be of some help, Markus


#19

I was wondering where you could get plastics.

Sharon


#20

You can make your own stakes from hard wood. An eighteen inch lenght of
dowel is easy to find and is a good place to start. Marylyn,

I’m really interested in this, I have a customer who wants an anaclastic
cuff bracelet. What diameter dowel are you using? Would something
hardwood like maple be better?

Wendy @Wendy_Newman