Silver tube casting.
 

Hello.
I use silver in my work, mainly I roll plates and draw wire. Often I
need to make silver tubes, half an inch in length, 0.314 inch (8 mm) in
diam and with a wall thickness of 0.0393701 inch (1mm). So I do the
tubing ouf of a silver plate but there are too many operations involved
(rolling, shaping, soldering, stretching), and Id like to make my
tubing at a large scale.

I have made a propane gas burner as in Ron Reil pages and it worked,
and I bought a medium sized crusible for centrifugal casting and made a
centrifuge but my burner wont heat up the crusible enough for the
silver to flow into the mould. The mould I employed was a drilled screw
3/8 and put a piece of 5/16 brass in the centre. Thing is molten silver
stuck in the crusible opening. I guess not enough temperature.

Since I am beginning to experiment with silver casting and keeping in
mind that I will be casting tubing (mainly) I would like to hear your
advice. Any of it sans the advice to quit, I must do this myself.

I tried to use "Alcohol investment" I picked up at a dental store, it
has 2 liquid components and a white powder, but from my first
experiment I did not got satisfactory results, the central piece of
investment(the one that stands for the hollow part) breaks too easily.
But then again I dont have a vibrating equipment required to shake the
investment neither I have a vacuum pump to remove air from the
investment.

Right now it occured to me making a small forge of bricks, stick my
burner in it and put my mould vertically in the centre of the 'forge'
with some silver on the top hoping it will melt and fill the tube like
cavity.

I greately apritiate any of your inputs.

Konstantin.

The brick forge worked out perfectly, tho my casting needs alot of
improvement.
Casting in a metal mould result in a welded piece of work using 925
grade silver. Lol.

Anyway it seems my problem reduces to :
How and what investment to to use for tube (nipple pipe) casting ?

The reason I got a welded piece of work is this.

I drilled 3/4" diameter screw, with a 3/8" 2" deep, then I drilled it
with a 5/16 through the rest of the screw, so I could put a 5/16" brass
rod to act as a hollow part of the pipe.
And I put some silver on the top and put it all in the forge, after
seeing the silver on top melting,
I turned off the torch. I have to mention that the screw was red hot. I
guess hot enough for the brass inside the hollow part of the screw to
melt in with the silver and this is how I got this thing soldered and
alloed.
I guess this is a No-No in casting.
Must use a cooler metalic mould to pour molten silver in it.



I never heard about making a tube out of a sheet of metal but I dont
think it is for me.

"Clamdigger" wrote in message
...
wrote:

Casting in a metal mould result in a welded piece of work using 925
grade silver. Lol.

I don't see why "casting in a metal mould (would) result in a welded
piece of work"

lead and zinc and alluminium are all cast to my knowledge in metal
molds. I have often cast lead in molds made of brass.

LOL!
What is silver solder made from?

Trust me - silver sticks.

I would not even consider casting these tiddly little tubes.
I'd clean up the lathe, install a pristine chip catcher, and machine them.

Beautiful finish, precise tolerance, no heat required, no grief. Turn out
dozens of them per hour. More, if you jigged up for it.

Machining has got to be the way to go.

If you don't have stock big enough, then cast some silver "blocks"
(mini-ingots) onto open air, fire-scaled steel (or clay) ingot moulds.

Works for me.

(I've tried the centrifugal casting method - steel moulds, sterling silver -
when making (finger) rings, and cursed for ages whilst I tried to
cold-chisel the silver out of the mould.)

--
Jeff R.

On 2 Jul 2005 16:24:54 -0700, wrote:

The reason I got a welded piece of work is this.

I drilled 3/4" diameter screw, with a 3/8" 2" deep, then I drilled it
with a 5/16 through the rest of the screw, so I could put a 5/16" brass
rod to act as a hollow part of the pipe.
And I put some silver on the top and put it all in the forge, after
seeing the silver on top melting,
I turned off the torch. I have to mention that the screw was red hot. I
guess hot enough for the brass inside the hollow part of the screw to
melt in with the silver and this is how I got this thing soldered and
alloed.
I guess this is a No-No in casting.
Must use a cooler metalic mould to pour molten silver in it.



I never heard about making a tube out of a sheet of metal but I dont
think it is for me.
Why not use lost wax casting? It would be very easy to make a mold for
the wax tubes and then cast them. I did this in high school. I needed
a tube that was about 3/8 OD and 5/16 ID. I rolled wax sheet around a
dowell for a mold, added sprues, and cast it with a centrifigul
caster. It came out nice.Also, you can get silver clay that is molded,
dried, and fired, After firing you will have a fine silver, not
sterling, piece. Rio Grand sells the silver clay. I'm sure it's
available other places too.
Eric R Snow

wrote in message
oups.com...
The reason I got a welded piece of work is this.

I drilled 3/4" diameter screw, with a 3/8" 2" deep, then I drilled it
with a 5/16 through the rest of the screw, so I could put a 5/16" brass
rod to act as a hollow part of the pipe.
And I put some silver on the top and put it all in the forge, after
seeing the silver on top melting,
I turned off the torch. I have to mention that the screw was red hot. I
guess hot enough for the brass inside the hollow part of the screw to
melt in with the silver and this is how I got this thing soldered and
alloed.
I guess this is a No-No in casting.
Must use a cooler metalic mould to pour molten silver in it.

You can't use brass as a mold, or a part of a mold, not for casting silver.
It melts at approximately the same temperature as sterling silver, and is
more than eager to solder to silver, even if you don't melt it. Further,
you shouldn't heat the mold by melting your metal in or on it. Your metal
should be heated independently of the mold, using either a small melting
dish (jewelry supply houses sell them) or a crucible. You should also
exercise care in melting silver, for it's easy to oxidize the base metal
(copper in sterling) and create a porous casting. A neutral to reducing
torch flame is in your best interest, or a furnace with a neutral or
reducing atmosphere if you melt in a crucible. The metal would be poured
into the mold when it has achieved a pouring temperature. If you cast by
using the investment process, the mold is poured hot, right out of the
burnout oven.

Silver has a strong affinity for most other metals, so using a metallic mold
of any kind is insane in this instance. It's very difficult to prevent
the silver from soldering, even when you don't use flux. If you'd like
to produce the silver tubes with success, and you have an ongoing demand for
them, you should explore *proper* investment casting. Properly done, you
can expect to hold .005" with no trouble. A jewelry supply house can
provide all the necessary equipment. You won't get set up without spending
some money, but it's the fastest and easiest way for you to produce this
item without getting involved in equipment to draw them from plate. If
you're curious about how it might turn out, ask a jewelry bench man to cast
a few for you. You could carve, or otherwise manufacture the wax models for
him to see how it works, minimizing the cost of your experiment. . If he
has a large centrifuge, he could tree up several of them at one time,
reducing the cost per item. Keep that in mind if you explore casting them
yourself in the future.

Harold

If you're tgrying to co z thin wall tube, you ain't gonna do it sithout
pressure casting methods. The surface tension of the silver will keep it
out of fine passages. The surface tension will keep it out of even passages
1/8" or larger so you have to force it into such passages. This is why
there is sling and centrificugal casting methods and the sprue has to be
long enough to provide the pressure to force the metal into the casting.

--
Why isn't there an Ozone Hole at the NORTH Pole?

Better yet would be to spin them on an arbor.

--
Why isn't there an Ozone Hole at the NORTH Pole?