I am interested in making a mold for a metal casting project. Do you have foundry classes?
Moved to “Fired Arts”, which I believe oversees the furnace.
Yes. There are classes occasionally.
Usually headed up by Paul ( @Hardsuit )
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Paul is indeed the guru of casting. What sort of thing did you want to cast, and was it in aluminum?
Thanks for replying. I’m hoping to make an 18 inch steel bar - as light as I can make it.
Here’s my limited knowledge:
You need a crucible for each metal you want to smelt. We’ve got one for aluminum, and maybe one for pewter. The back of my head says that steel works hotter than aluminum, but I don’t have a firm grip on that. Google or Wikipedia should be able to show you the melting temps of both.
What is the special bit that makes it easier to cast this rather than get a steel bar and machine it to spec?
The propane furnace fired arts has will not reach the temperatures needed to cast steel. It can do brass and aluminum.
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The maximum flame temperature for combustion for Propane is 3595°F This is in ideal conditions with oxygen. Therefore, it can melt steel at about 2500 degrees. But the forge needs to be designed to do so.
Like most forges, if you are burning air, you are introducing Nitrogen (about 70% which is heated in the reaction and naturally cools the flame temperature. even with a super efficient burner you will not get this kind of temperature, but don’t let that stop you. Almost as importantly you need to introduce and retain as much heat as possible within the forge. Steel melts at around 2500°F, it is not as hard as you think.
The temperature of the flame is largely irrelevant. The furnace is designed for aluminum and can probably heat to a suitable temperature for brass ~1700, but that would be pushing it. Frankly the equipment we had the last time I used it was marginal in terms of safety for aluminum, in my opinion.
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Also if the refractory is not rated for the temp, that may be an issue.
You need to consider two things… Temperature, and Heat They are distinctly different animals. Think about it this way… a candle flame and a campfire flame will have approximately the same flame temperature, but a campfire will boil a large pot of water, where a candle will never get it up to temperature, as heat is lost from the pot as fast as you put it in. Your flame in your forge may have the temperature (try melting a piece of fine steel wire) but you may not have (or be able to retain) enough heat to melt anything bigger.
One of the most efficient designs is one that uses a venturi and high gas pressure as opposed to a blower. Same principal though.
I should add… these temperatures destroy ceramic fiber wool, and molten steel destroys the floor of your forge… it is still fun though 
Anyways, a well designed forge is needed to melt steel with propane.
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You shall certainly require your own crucible.
Regarding the furnace’s capabilities:
The “model A” CLAIMS to be usable for “casting iron”.
That said, I’d talk with Paul, who has the most experience with the actual device in question, and ultimately, you’ve already seen Beth’s opinions, but she’d have the final say, as chairperson.
And because I’m a huge pain in the ass:
smelt vs. melt
In a nutshell: melting is changing state from solid to liquid; smelting is an extraction from ore, and typically involves chemicals and other sundry processes. With this equipment, you’ll be melting, which is what I expect was the intention.
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Aluminum, brass, and bronze is all we’re set up for, and to the best of my knowledge we have only done aluminum so far.
While the equipment we have may be technically capable of going to iron temps, I don’t think it is a good idea to try.
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Thank you everyone for your input. Maybe machining is the way to go for my project. Can you create a recessed area that does not go all the way through the metal when machining? Will the outside edges be smooth? I’ve appreciated all your help.
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Like so?
EDIT: found a better representation of what I think you want:
Depends on what you mean by “outside edges”, “smooth”, etc. but yeah. If you want “mirror finish” you’d need to polish, but they can be reasonably smooth right out of the mill if done properly, if you mean what I think you mean…
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Moved back to Machine Shop since the Fired Arts options have been discussed, and the discussion has moved back to machining… :dms: 
I think we can do this with the plasmacam and then TIG -r- up! 
You might need to move to Metal Shop …lol
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Can you tag “Paul”? Does he still work with it?
“Paul” is Paul Wilson, aka @Hardsuit
I do not know to where this lies in his current interests, but he is still the most experienced with the DMS equipment, as far as I know.