Shrinking a piece of jewelry

Jewelry Discussion
1

I have a line of amulets, they are about an inch and I have had
several requests to have them in charm size. Is there a way to do it,
or a company that could help me reduce the size of a piece for
production? Thank you for any you can offer!

All the best,
Michelle

2

A couple of options.

  1. make them smaller
  2. 3D scan then reduce them
  3. Use a shrinking media product to reduce the item, then take
    castings (may take a couple of steps).

Regards Charles from Oz

3 
I have a line of amulets, they are about an inch and I have had
several requests to have them in charm size. Is there a way to do
it, or a company that could help me reduce the size of a piece for
production? Thank you for any you can offer!

How about using high velocity electromagnetic forming? “The technique
involves quickly discharging a high energy capacitor bank through a
coil of wire to generate an extremely powerful, rapidly changing
magnetic field which then “forms” the metal to be fabricated. The
technique uses pulsed power to generate a very high current pulse
over a very short time interval. Although electromagnetic forming
works best with metals that have relatively high electrical
conductivity (such as copper, silver, or aluminum), it will also work
to a limited extent with poorer conducting metals or alloys such as
steel or nickel.”

4 
http://www.capturedlightning.com/frames/shrinker.html

I have been looking into this.

The interesting thing is that the piece of metal (usually a coin),
shrinks in one dimension, but expands in another.

So if you shrink a coin the face will shrink, and retain the detail,
but the thickness of the coin will increase, so there is no loss in
mass.

The other interesting side effect is that the metal work hardens.

From a casting point of view this is very exciting, especially when
the shrink and expansion can be controlled.

The pieces that have worked well so far have been coins, and you can
see problems when you shrink a coin with a hole in it or a square
coin.

However if you know what’s going to happen you can plan for it :slight_smile:

Shrinking casting attempts have failed in the past due to (I
believe) poor quality castings used in the experiments. The failures
were catastrophic, basically the castings exploded.

My contact has agreed to using some of my castings in some further
experiments. I will share results.

Regards Charles A.

5

Charles,

http://www.capturedlightning.com/frames/shrinker.html I have been
looking into this.

Rather evil and dangerous equipment,. The more safer techniques for
shrinking stuff tends to be more work and time than just making a
new smaller sample.

jeffD

6 
1) make them smaller 2) 3D scan then reduce them 3) Use a shrinking
media product to reduce the item, then take castings (may take a
couple of steps).

#1 and #2 of Charles’ list above are the same thing, just different
ways of going about it. There is no way to shrink an item from 1 inch
to 1/2 inch effectively by molding and shrinking. I once saw an
experiment of molding a coin, starting with a “mint” coin. After 6
moldings it was a blurry mess. Generally you figure 8% shrinkage for
molding, but it’s also not that simple. The shrinkage is selective
according to the pressures and orientation of the part in the mold.
Plus your noses and fingers (and the like) will simply shrink away
to nothing…

The OP is a common “wish” that sure would save a lot of effort, but
it just doesn’t work with molding - not by 1/2 scale or more, that
is.

7

Well, now, it is time to take up Precious Metal Clay. The item of
jewelry wanting to be shrunk can be pressed into RTV (Room
Temperature Vulcanizing material) and removed after the RTV has set
up. Then Standard PMC can be pressed into the mold. The Standard PMC
shrinks 25% when it is fired for 2 hours at 1650 degrees. There is
the first reduced item. Press the newly reduced smaller PMC fine
silver item into RTV again. Use another piece of Standard PMC and
press into the newest mold. Fire it the same amount of time - 2
hours/1650 degrees and you have another 25% reduction. Do this until
you have the desired reduction for a charm!

That is definitely in a nutshell, but I regularly do this to get
reduced items. I know, there is that dreaded word PMC - it does have
it’s place in the jewelry makin’s!

Rose Marie Christison

8

Hi John,

I guess I have to expand on my comments.

  1. Make them smaller… by hand.
  2. 3D scan them and reduce the model in your computer.
  3. There are products available that can retain detail, and shrink.
    Pretty good for a start.

Personally I’d either make the model by hand or do the lot by
computer, depending on the project.

Regards Charles A.

9

Hi JeffD,

Rather evil and dangerous equipment,. The more safer techniques
for shrinking stuff tends to be more work and time than just making
a new smaller sample.

That’s why I’m not going to conduct the experiment myself. I’ll
leave it to someone that a) has the equipment, and b) has the
experience to conduct the experiments safely.

Currently castings are mechanically poor in comparison with a hand
made piece, however if you could work harden the casting, they could
possibly be more durable pieces.

Regards Charles A.

10

You could make a mold from a 3D print. Before printing, reduce the
image.

http://uprint.dimensionprinting.com

I’d find some company or really rich person that owns one though. It
costs ONLY $14900.00 for the printer itself.

Val

11

Val,

Many Universities now have these 3B printers… usually in the
engineering depts. $15G is not bad considering what they cost ten
years ago. Some print in metal now using a laser to sinter the
material. Some use a liquid polymer, others use powder. Much larger
units are conceived for making buildings with concrete being placed
in layers like cake frosting.

Ric Furrer
Sturgeon Bay, WI