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Blanking dies II


#1

G’day: Told you I was numerically challenged, didn’t I? I just
sent the article to myself to see what happened, and found it is
only 6kb’s after all. So, make of it what you like; yere 'tiz:

BLANKING DIES

Jewellers often need small shapes with which to make up such
things as chains, pendants, earrings and so on. By small
shapes I mean items in silver or gold sheet about 0.5mm thick,
and around a maximum of 15mm diameter. These items can take the
shape of various flowers, leaves, hearts, stars or anything
else one’s imagination can dream up, and after suitable cleaning
up with a fine sanding disc on a handpiece, can be drilled to
accept jump rings, or have small jump rings soldered to them so
they can be formed into chains, Small flowers for instance can
have an earring post fitted, and a small stone, bezel-set in the
centre. There is really no limit to the need for such small
precious-metal items. But it is extremely laborious and boring
to have to hand-cut at least 20 identical items to make a chain,
so the answer is to stamp them out of sheet with a device called
a blanking die which you can make yourself as follows:- Take a
small piece of really flat steel about 1mm thick. I used a
piece from the top of a stout chemicals drum, cleaned up with
abrasive paper. Coat an area a bit larger than your design with
black marker ink, then using a strong needle mounted in a short
length of wood dowel, draw the design on the steel, but keep it
small. Choose a position on your design where a tiny hole will
be least noticed, mark with a fine centre-punch and drill with
the smallest drill you have, preferably smaller than 1mm. Now
put a #4 or #6 blade in your standard jewellers sawframe, thread
the free end of the blade through the hole, then fasten and
tighten the blade as usual. You will need a good light and to
saw with great care, for if you make a mistake, you can’t file
the design to shape as you will see later. Use long steady
strokes, keeping the saw as vertical as possible, blowing away
the metal dust continuously. (I use an aquarium aerator pump with
a thin tube attached to the sawframe.) Having cut out your
design, cut round the open part of the metal which - to be
old-fashioned sexist - I call the female part of the die,
leaving it in the centre of a 25mm square of steel. Next obtain
a strip of mild steel 25mm wide, 3mm thick and about 600mm long.
Mark the centre of the length and bend it into a narrow U so
that the two ends are the same length. Using a bit of water pipe
about 30mm diameter (or whatever is suitable to hand) and
squeeze the strip round it in a strong bench vice to form a rough
loop instead of the U so it looks something like this when edge
on: C That is the frame of the
blanking die. About 60mm from the ends and in the centre of the
strip drill a 3mm hole through both the ends, and hard-solder
one end a piece of 3mm steel rod 25mm long into one of the
holes. You will have to put a very slight curve into the rod so
that it moves fairly easily in the other hole when the die frame
is flexed, for this is to assure proper registration of the two
parts of the die. Now you have to rivet the female die onto the
inside of one of the ends; you’ll find it easiest to clamp the
die to the frame to drill the 1mm rivet holes through frame and
die, then remove the die in order to countersink them. Rivets
can be made from 1mm copper or brass wire; flux the end and melt
it into a little ball with a fine hot flame, file the end of the
ball flat and cut off the wire to a suitable length and voila!
Your rivet awaits riveting. Having securely riveted the female
die to the frame, file the rivet heads completely flush with
the surface of the die. Now mark where the female die closed on
the other fork of the frame, clean this very thoroughly indeed
then paint the cleaned area with zinc chloride flux or any other
soft-soldering flux obtainable from the DIY shops. Now you ‘tin’
that area with soft solder. (You know; the lead-based stuff, not
jewellers solders). Clean one side of the male die and
carefully ‘tin’ that in a similar way, being very careful not to
allow any solder to adhere to the sides of the male die. Place
the male die - tinned side up - in the female die, close the
forks of the frame and lock them together with a C clamp. And
heat the fork holding the male die until the solder melts and
’welds’ the male to the fork. Cool the hot area under the tap
and carefully wash off all the soft-soldering flux, otherwise
you will get corrosion after a very short while. To use the
blanking die, put the forks in a stout bench vise, and close the
jaws, but leaving enough room to insert a piece of 0.5mm silver
or gold sheet between the dies, then close the vise fairly
sharply. A crunch will be heard as the shape is stamped out of
the metal sheet. As it might be difficult to remove the blank
from the female die, you will need to have drilled a 3 mm hole
through the frame to emerge in the centre of the die, so that a
piece of bamboo skewer can be used to push out the blank. You
will see that the edges of the blank are a little cupped, but a
bit of gentle work with a hide or nylon hammer on a polised
anvil will flatten it, and you’ll be ready to clean it up with a
fine file or handpiece sanding disc. It’s then up to you what
you use it for, but if the blanking die is made as above you will
be able to get at least 30 blanks from it before it gets too
blunt. Want it to last longer than that? Well, when you have
cut out your male and female dies, drill the necessary holes and
countersinks in the female bit, then use a commercial
case-hardening compound such as Kasenit to really harden the
surfaces of the dies - and that’s it; carry on exactly as before.
I have about 10 blanking dies such as I have described, and
have made a whole swag of earrings, chains, pendants, etc which
use the various blanks - in various guises Enjoy! – /\ / / John
Burgess, / / / //\ johnb@ts.co.nz / / \ \ / (___) \ (_________)


#2

John,

Just wanted to thank you for your disertation on blanking dies.
Everytime I even think of using a small part repetitively I
change my design and wish I had someone who could stamp them out
for me. This info is like a dream come true.

Thanks so much & g’day.

Sharon


#3

Thank you John for such helpfull Great for a
small studio like mine. I don’t cast but want to make
fabricated multiples, often requiring a major time investment.
I’m excited about trying this technique!
Carrie Nunes


#4

Hi…Thanks for an interesting approach to blanking dies.

For those of you that have followed this thread and would like
to see some drawings of the technique that help to visualize the
process, check out my website. In the “Learn” section, is a unit
called “combined matrix blanking dies” that shows how to first
form a part and then use the blanking die to trim away the outer
edge, or flange.

Blanking dies have been around for quite a while in the
industrial world. They were first introduced by the DOALL
band-saw company in the early '30’s and the concept was patented
as “The Continental Die Cutting Method”. Obviously the patent ran
out a long time ago. Douglas Aircraft used the technique in the
fabrication of the DC-3 airplane.

Dave Shelton has a die cutting service that produces blanking
dies to your design. All you do is send him your art-work and you
get back a heat treated tool steel die that will last for
thousands of parts. He can be reached at: 505-256-7073.

There is an excellent chapter in Susan Kingsley’s book
"Hydraulic Die Forming for Jewelers & Metalsmiths" on blanking
dies. It includes directions on how to saw out the dies, as well
as heat treating. With all due respect to John, it is not quite
as easy as he makes it sound and for best performance, the saw
cut should be done at a very specific angle to eliminate pulling
and burring. A properly made blanking die will cut paper or 36
gauge foil. This cannot be done by just sawing out your outline
in a piece of metal and calling it a blanking die.
Lee Marshall
Bonny Doon Engineering http://www.bonnydoonengineering.com