I have a question about crucibles

[ConchoMan]

Ok here is the deal, I am wanting to make a knife. Now to make it I am hoping to use iron ore from the Llano area. I just happen to have a supply of black sands concentrates from my gold panning adventures. I have about 2 pounds of it. Now I figure only about half of it is actual iron the rest is either hematite or other sand to sub sand grain sized heavy gem stones and I plan to use a magnet to separate it out. I got the idea to make a knife out of it from the history channel when they made an axe out of some meteorites. I figure I will make the blade then add some high carbon steel from a junk file to the blade edge so that it is actually usable. My only question is what type of crucible I will need. I have cast some jewelry but my casting machine and crucible is way to small to melt this much material. I also have plenty of lime stone for flux. You thoughts would be appreciated. Thanks

[matt87]

Hi and welcome ConchoMan.

I hate to say this, but what you plan to do isn't really very feasible. Pure iron melts at over 1500 degrees C (2800 F) and is likely to oxidise (burn) before it reaches this temperature. 'Cast' iron is really iron with between 2.2 and 4% carbon (by weight) and thus its melting point is lower than pure iron (though still much higher than most nonferrous metals). This high carbon content makes it brittle and generally not suited to a knife. It cannot be forged or firewelded to pure iron or steel either.

You will get better results by building an ironsmelting furnace, and feeding the blacksand into that. These furnaces, when operated correctly, produce a very hot reducing atmosphere, i.e. one where there is free carbon but no free oxygen. This precludes oxidisation. You do need a lot of feedstock, and you don't get much out. What you are left with is one or more 'blooms', spongey, irregular masses of iron and/or steel... if you're lucky. You will need to fireweld these together and work them into a useful billet. THEN you start the forging of the knife. Suffice to say, it's not really for beginners (or the faint-hearted).

There are though much more practicable ways for people to start smiting, which are well documented on this site. They would probably be a better place to get started in knife-making. After all, you don't want to go through all that work in smelting the stock for your knife, only to destroy it due to your inexperience!

[Rich Hale]

SEveral groups arend the states get together and do what you are proposing. The one I am familiar with tells me it is about a three day constant process from start to end to make a glob of stuff from black sand. Some how they figure out what to use and how to use it for forgeing into billets taht will be used in blades. A lot of the things a smith does or can do can be figured out by one with sonme basic knowledge of how to learn while working. and most of the more advanced stuff can be learned through instructional methods. To foreg this blade from sand you may be looking at a ten yrear period of trial and error on your own and may cut that into fourths if you get into a group that will take you under there wing. With a professional seeing you into this area maybe a year or two would be your investment. Or you can use steel that is already made and with a couple of years experience makes some knives.

[Bentiron1946]

I have seen this film but if you want your own copy to see a primitve way of smelting iron it shows you how to do it from start to finish.INAGINA, the last house of iron

[ConchoMan]

Thanks for the help. It was just something that I had the idea for since I have the black sands already. I have made some blades from truck springs and one from a broken chrome vanadium ratchet extension. I also have a small billet of Damascus that is a mix of rebar, file peices, and some valves from a small block chevy motor. I think I may not after all try making one from scratch. Though I may try it in the future.

[ThomasPowers]

There are some smiths who do do crucible smelting of magnitite. The big thing is not flux, flux takes iron OUT of the system so you want as little as possible only enough to shelter the iron from oxygen. What you need is the carbon donor to create carbon monoxide to yank the oxygen off the iron and take it away. (happens above 1000C in most smelters)

I use a bloomery and so am not up on all the details. IIRC there was a thread about this on the old neotribal blacksmiths website, Trying to remember if it was Tai Goo or Tim Lively that did the crucible smelting.

[jlw50]

Check out this site: Tale of the Tatara : Types of Iron Sand