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High-Performance Blades Sharing ideas for getting the most out of our steel.

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  #1  
Old 09-26-2006, 04:32 PM
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B.Finnigan B.Finnigan is offline
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Smelting and casting recipes.

This thread will be a reference resource for recipes used for smelting or casting. It will be stickied so nobody has to hunt it down amongst all the other threads. This thread should be a very dynamic and continuously updated one so check it often.

Basic iron smelting recipe/process:

This is the process I used for my first succesful iron smelt. There are many different styles of furnaces and processes. I find all of them facinating and intriguing. My goal is to try all of them.

I used a #3 graphite crucible and filled it to just an inch from the top rim with hematite. I mixed in a 1/2 tsp of calsium carbonate for flux. Flux helps the seperation of iron from the other minerals. After the crucible has been filled I topped it with crushed glass. The glass when melted will form an oxygen barrier but still allow the gases from the melt to escape. The molten glass also acts as a trap for the silica/quartz impurities that will float to the top.

I then placed it in the forge that was pre-heated. You want to put a piece of cardboard under the crucible so it will not fuse with the material on your forge floor. The cardboard will leave a thin layer of carbon between the crucible and forge floor.

The forge I used was a propane blown forge and it only took a few minutes to get up near iron melting temps. I did not have a temp probe so I cranked up the forge until the interior and the crucible was a very bright yellow, almost white color. It should be bright enough that you will need sunglasses to look at it.



You need to position the crucible so you can see the molten glass layer and watch the bubble activity. When the bubble ativity greatly slows down or stops all together then the smelt is done and it is time for a long slow cool down.

After the crucible has cooled off, in my case it was 2 1/2 hrs, you then have to break the black glass/slag layer up since your iron button will be at the bottom. The breaking process can be a bit tedious since you want to break the slag but not damage the crucible. Alot of little taps in the center will start to fracture the slag. Once it starts to fracture then it gets easier to get the rest out. So far I have blown the bottom out of two of them, one was a SiC ($$$$$), so even being careful is no Guarantee that you will be able to use it again.

When you get to the iron button it will look like this(hopefully).



It will have a swiss cheese look to it but if it has too many holes then your chances of having a void after you forge it out greatly increase. It is now ready to become wrought iron which means you will need to normalize it a couple times and then hammer forge(wrought) it to shape. You will need to use welding temps to make sure all of the voids close up. The hammering will squeeze out any slag and close up the voids.

This is not the only way to smelt, there are many different processes and ingredient combinations. This thread is to be a resource for all of us to see how different people smelt and what techniques they use.

If you think knifemaking is frustrating wait until you try smelting. When you get frustrated keep in mind that this was being done over two thousand years ago and without propane, graphite and electric blowers. You can do it! Just keep trying and take good notes, don't be afraid to ask questions. I doubt anyone had a perfect button on thier first try.

Those of you that have smelted I hope you post your recipes and techniques here. This is not a thread for "my process is better then yours" or deep complex disertations on metalurgy, but rather a basic starting point for those that want to play around with it.

Other smelting forums have degraded into argumentive pissing matches about terminology and historical techniques. That is why me, Carl Price and Jerry Bennet wanted to have a new smelting arena with a whole new attitude and tone. I hope all of us can use this forum in a healthy, informative and inspirational way to learn and expirement.

Last edited by B.Finnigan; 10-11-2006 at 05:17 PM.
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Old 09-29-2006, 05:52 PM
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B.Finnigan B.Finnigan is offline
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Carbon steel alloying.

Using the above process you can also alloy your own carbon steel. If you have access to any automotive repair shop that turns brake rotors and drums you can get the turnings. These turnings are cast iron and all you need to do to them is dilute them with mild steel.
I use a 70/30 mixture of cast iron turnings 70% by weight and mild steel 30% by weight.
Cast iron has at least 2% carbon and most often much higher.

Considering the carbon uptake from graphite crucibles I have the best luck by only using 30% brake drum turnings. The buttons spark test between .5 and .9% carbon which is a good range for blade steel.

My local Les Schwabb tire store gives me as much turnings as I can pack out of there. I usually bring a knife or button that I have made and show them. They get a great kick out of seeing what I have been doing with something they would normally just throw out.

I have to make my own mild steel cuttings on the band saw. The smaller the alloying metals are the faster they melt and tend to mix better. I know many smelters that use assorted scrap pieces that are not all small cuttings and they still get good results. I just like to take as much of the risk out as possible so as to not anger the smelting gods. The smelting gods require alot of sacrificial offerings before they even think about smiling down upon you.
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Old 09-29-2006, 11:08 PM
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Mike Turner Mike Turner is offline
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Hey Brent what was the cfm on the blower? I have a 134 cfm and I get it to almost the dripping stage I have been wanting to change the blower anyway I robbed this one from my coal forge and it wants to go back to the coal forge. Can't wait to try this and thanks for sharing.

Mike
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Old 09-30-2006, 09:18 AM
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B.Finnigan B.Finnigan is offline
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I use a 100 CFM blower and a 1/8" orfice. If the forge will get to welding temps then it will get to smelting temps also. It just takes a few more minutes but once it gets there it will maintain. The insulation and refractory that are being used play an important role in raising the temps.

I would like to see some other smelters post some info on smelting furnaces. I destroyed the inside of my forge with only two smelts. If I was to continue smelting with propane I would want to have a seperate furnace that would be dedicated to smelting with a better design to withstand the heat. You can actually melt ITC 100 which will then eat the insul wool.
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Old 09-30-2006, 11:39 AM
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Mike Turner Mike Turner is offline
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The refractory that I used is the 3000 deg castable. It has no trouble getting to welding temp. I think we need a melting smily!!!

Mike
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Old 10-14-2006, 04:45 PM
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B.Finnigan B.Finnigan is offline
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This is what you get when you use inferior hematite. Greenish black glass, if I had a little more I could probably re-melt it and make welding goggles since it it dark enough.

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