Thanks Gene,
I appreciate the time taken to give me some ideas.
Have you ever sand cast something as thin as what I have mentioned in my initial inquiry? Something flat and about 5/16 at the thickest and tapering down to an edge? Because I have never done any casting only studied in theory at this point I have a hard time seeing the splitting of a cope and drag that would maintain such small dimensions, do you know what I mean? I know the casting sand has a "sticking" component to hold it's shape but how well for such fine detail. I realize I'd have to do some oversizing of the mold,and some dressing of the part. I've got no problem with that. I do fabricate brass parts for horns and have used silver solder techniques to fill voids etc.. If I could just get close to a consistently contoured part I'd be a happy man.

I appreciate the offer but I am getting to the point in my repair and refurbishing that in order to save time and become more efficient at what I am doing I have to become familiar with casting techniques. There are many other parts that would be much easier to make by casting. I enjoy the thought of actually doing it myself and want to persue it on my own. thanks again

Thanks everyone who responded. Lots of good info here. Now I have to figure out a game plan and get to it.
Has anyone made their own furnace? I have a number of good books and it seems simple enough. Besides the mechanical aspects of making the furnace I have gleaned from the info I have that it is important to "season" the inside refractory cement b4 using and pay attention to not shocking the "system" to keep stuff from cracking. I do plan on constructing my own furnace. The commercially available furnaces are much bigger than I need.
Any other insights would be appreciated.
thanks again.

Hi Maddahorn,
In another life I ran a steam plant. When the masons repaired the refractory, two elements needed curing; the cement that was basically used to wet the bricks, soaps and tiles and the plastic refractory. Both the wetting cement and the plastic refractory contained water.We would use a salamander to cure the new work for at least twenty four hours before firing the boiler. Then we would keep a small fire for another day. These were wood fired boilers but easily reached a 1600 degree fire.
The floors were made using fire brick suspended on cast iron rails. A space between the bricks allowed the forced draft to come from under the fire. These bricks sustained the punishment of rakes scraping the sand, rocks, slow dogs, what ever several times a day and yet lasted for around a year.
Frank

Maddahorn,

For the work you're going to be doing, you'll need both a burnout kiln and a melting furnace. Two definitely different critters.

The burnout kiln for flasks the size you'll probably be using could easily be made by stacking up soft firebrick and developing the heat using salvaged burners from an old electric stove. One or two of the top burners would develop sufficient heat, and the controls for them will work fine for burnouts. It's crude, but effective and dirt cheap. I've built several of them this way, then switched to "rolling my own" coiled nichrome wire heating elements, but still using the stove controls. Why not, when they're free?

For a melting furnace for brasses, you need to be able to develop and sustain temps around 2500 degrees Fahrenheit, so you need to use a high quality rammable or castable refractory. A simple blown gas burner will do fine, shouldn't take more than 50cfm blower and a 20# propane picninc cylinder will supply all the gas you need. Check around the web for designs for blown burners on places like the backyard caster's forums, or on the blacksmiths' forums.

I've used a simple blown burner set into the side of a 5 gallon oil drum lined with castable refractory very successfully. You can also use refractory fiber insulation such as Kaowool or Inswool, but it needs to be top coated with something such as Plistix 900 or ITC-100. The fiber is too fragile, otherwise. Such a furnace will handle a crucible capable of melting ten or more pounds of brass, and can easily be scaled down to fit your needs.

The starting point is to determine how much metal you need to melt, then double that figure for your crucible size. From there, you take the dimensions of the crucible and size the furnace to it. For the small amounts you're probably going to be wanting, you might very well be able to simply melt the brass in a crucible mounted on a centrifugal casting machine. The one I have will take a crucible that will melt 4 ounces of silver easily, and I believe larger ones may be available. Again, determine what you need and see what is available at Rio Grande or someone similar.

Hope this helps. Ask as many questions as you need to get where you want to go. We'll try to help.

Rich

Thanks Rich, but what is a burnout kiln? used for?

For a furnace I was thinking not much bigger than a coffee can size for the work I'll be doing and amount of material needed for the parts. I have a few choices relative to plans from books I've bought.
Can you recommend a favourite source to order yellow brass?
thanks again
fred

In the cire perdue, or "lost wax" casting process, the model is made of a wax designed for the purpose.  After the wax model is made, it is sprued, gated and risered to a sprue cup form and surrounded by investment plaster.  This makes up what is known as the "flask", or the mold.  Once the investment flask has set, it is then put into the burnout kiln and carefully brought up to a temperature at which the wax is completely burned out of the plaster, leaving a cavity that will be filled with molten metal.

It is necessary to use a controllable kiln for the burnout process inordeer to properly calcine the investment plaster, ensure total removal of the wax, and have the mold at a suitable temperature for the actual casting process so that there is less chance of getting incomplete fill in the mold.  The temperature required for to calcine the plaster is about 550F and the burnout requires about 1200F for best results.  1200F is also about the right temp for the flask to be at when the molten metal is introduced. 

The burnout process doesn't require a terribly high degree of control, just reasonable.  Proportional cycling switches for the elements will be fine, (the kind on the stovetop burners), and a bit of attention during the process.  You can, of course, use PLCs and a computer to automate the process down to a gnat's whisker, but that's overkill for what you're doing, I think.

Rich

Thanks Rich for all the info. You've been a big help.
I know what you are talking about re: burnout proceedure. I'm still not "up" on my casting jargon.

Can anyone recommend a source for yellow brass ingots for casting purposes? There are a few places I googled and not sure if it matters who or where you get them from.

What really matters on the casting ingots is which alloy you get. There are hundreds of different copper alloys, and each one has different characteristics. You can find a lot of background information on the various alloys at: http://www.copper.org/  

I get my copper alloys from Atlas Metals in Denver: http://www.atlasmetal.com/   I've found their people to be knowledgeable and helpful whenever I've had questions. 

Rich