Hi I have attached a picture of a style of bangle I would like to
make. My design is different, but the connection is similar where it
uses tension to open then cuff and then keep the clasp secure in its
closed position.
My question is that I want to produce 20-30 of these and want to use
an approach that will require the least amount of work. The image is
for a brass one, but I will be making my design in 14K Yellow Gold.
How do these factories make the bangles?
Do they cast from a mold that has the bangle in the shape already
and they just adjust it to position so the hinge works?
or
Do they cast flat metal strips in the right shape of the design and
hammer it into shape and position?
Cast? No. Those are stamped. You need a decent sized punch press
(and a custom made die) to do that, as well as a supply of 14KY
sheet, but after that, you can turn one out every few seconds. No
way you’re going to be able to compete on price with a piece like
that. So I’d look very carefully at changing the design into
something that can’t just be stamped out of sheet metal by someone
who makes much less money than you should be making.
On a limited production basis, you can make them up out of strip,
but you’ll have a fair bit of wastage.
Rethink your design. Take it somewhere the machines can’t follow.
No casting at all. A piece like this will be cut or stamped from
sheet stock.
Cast metal has insufficient elasticity, i. e., springiness, to
function in such a design. Cast metal also would be prone to cracking
due to bending stress.
Looks like you will be buying a lot of gold. I don’t cast and I
suspect that you won’t want to cast this piece either. It will be
hard and tend to crack over time and have to be fairly thick to cast
it. Again, I don’t cast. Those who do may have different ideas. I
make a hooked bracelet. It is the only solid bracelet I make that
isn’t a cuff. Following is a picture in a slightly older style than
I do now.
The standard size is 7.25 inches from hook to hole before the
bracelet is bent. This is the first measurement that you will have
to deal with as you need to be able fit the wrists of your intended
market, so just accordingly. This type of bracelet needs to be rigid
enough to stay hooked or it might be lost. This is a accomplished by
making sure that the body of the bracelet is hard enough or tempered
such that it has some spring or memory. You control this either by
how much you roll the material or the level of hardness in it when
you buy the stock. This may take some experimentation. I usually
just add a few passes thru the roller after I finish any fabrication
steps that might have annealed the bracelet too much. It also will
allow you to use thinner material. This will be a real important
consideration if you are working in gold.
The shape that you intend to use is fairly simple and you can
probably layout multiple pieces nestled togeather on a piece of
sheet such that there is little waste. There will be some waste that
you can cast, roll, and draw into the wire that you need for the
clasp. I would avoid trying to saw or cut out the shape with shears.
This will distort the metal and make more work. The size of this
project might justify buying a bench shear or guillotine. I would
love to buy one myself. The clasp hole will have to be pierced or
you might be able to have a punch made in that shape. Before you do
any of this, talk to your metal supplier (Hoover and Strong, Rio
Grande, Stuller etc.) and see if they will sell you already made
blanks. They might even sell you the finished piece. If you buy
sheet and cut it out yourself, consider doing any rolling and
prepolishing before you cut out the blanks. This may save you time
and give some consistency to your finish. The clasp is just a piece
of maybe 8 or 10 gauge wire with a flattened ball soldered to it.
You make the ball by cutting a piece of wire and melting it into a
ball shape in a small depression in an old charcoal block. This is
another opportunity to experiment. Be sure to hard solder the ball
to the wire and use a lower melting point solder to solder the wire
and ball to the bracelet base (I usually forget this step). Work the
whole piece flat including any finishing. The last step is to shape
it on a bracelet mandrel, piece of PVC or metal pipe, baseball bat
or whatever works. Looks like fun, at least the first couple until
you get it right. After that, it is just work. Good luck. Rob
First of all, where are you? hopefully in a large town as you may
need to have help from a sheet metal workshop please advise.
The picture you show is made from sheet material approximately 25mm
wide by 1.5 to 2mm thick in a half hard condition. Just guillotined
to shape .Then the keyhole shape is punched through on a press with a
punch and die. Then the flat strip is put through a small 3 roll
bender.
Then the pin is made from bar stock turned down in a lathe.
A hole is drilled in the sheet and the pin is riveted from the
inside to secure it to the sheet. All cold work.
If you are a small bench maker? then to do this as I have described
is a long process. A sheet metal workshop when they have set up the
tooling will make this in less than half an hour, like myself.
You need to cost out your gold cost FIRST as this will be much more
expensive than you think. You will need to start with a strip of
gold some 175mm long by 25 mm wide. Get your gold supplier to quote
you.
Then decide if you haver enough customers to pay you.
For this style of clasp to work you need metal with spring in it.
Casting will not do. Best to have it die struck or hand pierce
factory plate stick and then hammer into shape.
The bangle is certainly not casted. It is stamped & handcrafted. In
India the goldsmiths will do this work mostly in 22K. In 14K one
would have to inquire. Losses & time consumption is crucial.
Thank you all for the replies. So I have decided to make a much
simpler version [SEE ATTACHMENT] with all the recommendations. I am
in the US (Texas) and we have our own workshop, but have not done
bangles like this before. This is the process I plan on following
based on all your help.
Theres nothing wrong with your idea, except that its too much like a
spring clip I use on my car rad hose. Not exactly a unique product
of a goldsmiths workshop. If you dream of making it into the bigtime,
you need to work in a proper goldSMITHS workshop for a couple of yrs.
Id give you a bangle I made, with the metal and tools and make you
work out how it was done!! Then youd make some real progress.
Re riveting, Google for rivets and riveting. Do your research. for 2
mm bangle material you make the catch like a dumbel, with a short
extension, this goes through the hole in the bangle and then has
this extension dressed over with a set into a half round form. All
cold, plenty strong enough for purpose, no heat, no flux, no solder,
and fast.
I don't have a 3 roll bender but am willing to buy one. anyone have
a recommendation of which one to buy?
Why do you need this to make this bangle? Also why do you need to
cast the pin? Not just make one from stock metal? Also 18 kt would be
a better gold alloy to use.
Ted here, I suggested he look out for a 3 roll bender, cos I use one
and its so much easier than bashing it round a mandrel.
Especially as the metal will be half hard. Mine has 9in long rolls
by 1in dia.
Also ive one that has concave/ convex rolls for 3d bangles, ie not
flat ones.
But hey, im a production shop. As Brian has so well said, take it
where the machine cant go, or like me, take the machine where no one
has gone before.
