Casting Silver.

[Twice boom]

I'm setting my shop for making knives that will require casting Silver,pewter,brass,etc. What I need is plans for making a some kind of casting furnace . I been looking at Google with out success. So I am wondering if any members have a source they can turn me on for plans or give me instruction on how to go about making something they themselves have made for casing soft metals..

I've tried in the past melting Stirling silver in my forge. The only thing I managed was to burn a nice hole in my cast iron antique ladle..
Twice.

 

[necchi]

Silver melt temps are pretty high, and require crusibles for a pot. Search the web for Jewlery making info. I've made stuff with pewter and the cuttle bone technique. But pewter melts like lead. Here's a link that might send ya in the right direction.



http://en.allexperts.com/q/Jewelry-Making-3236/melting-silver-casting.htm

 

[Twice boom]

Thanks for the Link Necchi, I was able to find what I was looking for.
Twice.

 

[44-henry]

I have students in a technical design course cast silver jewerly in our lab using the lost wax method. We melt it 1-2 ounces at a time using an oxy acetylene torch (somewhat dirty oxy propane would be better). If your not going to do large castings this would be a cheap way to go. We use a vacuum casting table from Rio Grande and a small electric kiln to burn out the flasks. All of this could be made in a pinch.

 

[necchi]

Hey Alex, when doing lost wax, what do you use for the making actual casting die? Plaster of paris?
If so how thick does the plaster layer need to be to not burn through with the melted silver?

 

[FPDoc]

I did a lot of custom gold and silver work in the 70s. I always used something like this (fleabay ad excerpt)

New Kerr Lab Satin Cast 20

This is a new box of Kerr Lab Satin Cast 20
Allows you to achieve first rate casting quality
Through extensive research and development, this satin-smooth casting investment meets the technological demands of today's cutting-edge casting operations
Top jewelry casters from around the world know this casting investment for its ability to meet the highest demands for excellence
Satin cast produces a consistent finish on all your casting
The extra-smooth finish and clean breakaway characteristics help reduce your finishing time and increase your productivity
It's special formula includes wetting agents that help the investment blend to a smooth consistency without creating air bubbles
Additional wetting agents are neither necessary nor recommended
It forms a strong mold that is still permeable for creating full-fill castings with either vacuum or centrifugal equipment
Even with its high-strength bond, it breaks away easily at quenching which reduces your cleanup time
Every time you cast gold, silver, brass or other metals that melt at less than 2,000° F (1093° C) it provides quality results.

If you are centrifugal casting/vacuum casting or steam or pressure casting the last thing you want is for a mold to come apart and sling molten metal all around your workroom.

 

[Twice boom]

Alex thanks for your input. I dodn't believe I will have great call for casting . My intent is to learn how to. It seems hard but like anything else if you learn few of the inside tricks I can learn with out too much problem. My fingers are crossed as I type this... :haha:
Few scales for folders and few more for none folding knives is probable all I will do,unless someone got to have one of mine...

Its nice to know how is what's more important.
Twice.

 

[44-henry]

We use an Kerr Investment for all the castings we do, other types our available. Some folks use injection molds to make the wax patterns, we use a variety of processes to make our patterns, but generally they are custom jobs. The wax is not your normal candle crayon type wax (though that will work) and different types each have their own unique properties making them more suitable for different tasks. If you want to try the process on the cheap than check out steam pressure casting. There is a guy on the net that describes how to do the process with a tuna fish can for the pressure unit and a tomatoe paste can for the flask. Not a heck of a lot more sophisticated than that, but he gets nice results. Last Tuesday I had 21 students who cast jewelry out of silver for the first time in their lives and only one out of the group had a defective casting. If they can do it I'm sure you can manage it also, plus it is lots of fun.

 

[FPDoc]

Steam pressure casting is pretty straight forward and definitely cost effective.. tuna can, broomstick, asbestos cloth or burlap or whatever the heck you have. and any other can smaller than the tuna can in diameter. The cloth is tacked into the tuna can with the broomstick piece tacked as a handle on the bottom side. The cloth is wet. the other can is the flask with the burned out wax mold. you pour the molten metal into the flask and make sure there is a button big enough that when you slam the tuna can onto it (while the metal is molten) the wet cloth hits the red-hot button of casting metal.. instant steam.. gives the pressure to force the metal into the mold.

 

[Twice boom]

Let me see if I have this correct..

You wet the cloth and lay it at the bottom of the tuna can then tack it .Staples? the broom handle gets tacked at the bottom of the same can?

Now, is the molten metal gets poured in the can with the mold? Then the can with the wet cloth is placed over top of the can with the mold and pushed until it bottoms out... I'm visualizing a hydraulic affect...Is this correct?

Twice.

 

[FPDoc]

Yes, you have a wet pad of cloth inside the tuna can with a handle on the outside. When the wet cloth hits and seals the tuna can over the "flask" (mold can) the hot and STILL MOLTEN metal flashes the water to steam and the pressure of the steam forces the molten metal into the recesses of the lost-wax mold. It takes some timing to coordinate it all. The "flasks" have top and bottom cut out with the investment contained inside, that way whatever method you are using to cast (vacuum machine, centrifugal (machine or "sling"), steam etc. the air inside the mold can pass through the investment and "out of the way".

 

[Twice boom]

Thanks I'll put this thread in my favorites.

Sounds straight forward like you said.
Thanks a bunch.
Twice.