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I've been trying to make a knife by finding scrap, grinding/shaping it, then hardening it. The ones I have so far are alright, but they lose their edge way too quickly. I was just wondering what kind of scrap metal would be best to use. I know old files are best, but is there anything else I could use that might be easier to get hold of?
 

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veldskoen no socks
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I dont think you can harden mild steel any harder than it already is, not in the garden anyway, so the blacksmith at work tells me.
As Sticks said you need to find some thing along the lines of old lawnmower stuff or even old leaf springs from a car.
There is a thread in the knife section that tells you what metals are good.
 

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Darting from the shadows
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Yea mate, depending on how thick you want the blade, old saw blades work good for the likes of filleting knives.
 

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Darting from the shadows
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Hello , a mate of mine makes fine quality knives, he uses old chainsaw bars, he rekons the steel in these is next to none
yours Barry, down uder
Thats interesting mate, I knew chainsaw chains were awesome for it, but not the bar. :thumb:

And welcome to the site.
 

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Rail road ties.. they work very well also if you can get scrap railroad track it be very good expecally if its the heavy duty track type.. railroad steel is very tough more so then what they normaly put into buildings but its expensive because of it..
 

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You can "case harden" mild steel, but it requires a little bit of doing. I wouldn't start with a file unless you have adequate facilities to properly anneal it. Once you get down below the surface layers of a file, the metal is pretty soft.

If you want to start with mild steel, form the steel to shape, then you will need to place it in a fireproof airtight container filled with some source of carbon. The old timers used a mixture of powdered bone, charcoal, and ground up leather bits. You can also get commercial case hardening powders (like PackIn, available from www.mcmaster.com). Then you will need to get it good and hot, usually in the 1700 degrees F for at least a half hour or so. The carbon in the bone/charcoal/leather will -in effect- "vaporize" and make carbon monoxide (CO). This carbon monoxide will integrate into the pores in the metal and increase the carbon content of the steel. Up to a point, the longer you leave it in the heat, the deeper it will harden. Then, pull it out quickly and quench it. If you have a fairly thick part, water or saltwater will work okay. If your part is thin, it is best to use mineral oil to cool it more slowly to avoid cracking it. Move it up and down and twist it at a moderate speed in the quenching solution. This procedure will cause the outside of the metal to become very hard, while the inside is softer and more resilient. This gives a good blend of hardness and toughness. [Too hard and it gets brittle, too soft and it won't take/keep an edge]

You can try a coil spring from a car, but it will require some blacksmithing skills to straighten and pound it out. It is pretty good steel though.

Another thing you could try is ordering tool steel through www.mcmaster.com or www.use-enco.com. Both of these places stock tool steel in a variety of shapes and sizes. The McMaster website even has a primer on tool steels.
 

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survivalist
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Most rail road spikes and rails in the U.S. are too low in carbon to harden properly and hold a good edge.Old auto leaf springs, if not to thick work well as does lawn mower blades. For your first few attempts try a high carbon low alloy steel. Check out some of the knife maker suppliers like Texas knifemaker`s supply or K&G finishing supplies for some thing like O1, 1095 or 5160
 

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Darting from the shadows
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If you want to start with mild steel, form the steel to shape, then you will need to place it in a fireproof airtight container filled with some source of carbon. The old timers used a mixture of powdered bone, charcoal, and ground up leather bits. You can also get commercial case hardening powders (like PackIn, available from www.mcmaster.com). Then you will need to get it good and hot, usually in the 1700 degrees F for at least a half hour or so. The carbon in the bone/charcoal/leather will -in effect- "vaporize" and make carbon monoxide (CO). This carbon monoxide will integrate into the pores in the metal and increase the carbon content of the steel. Up to a point, the longer you leave it in the heat, the deeper it will harden. Then, pull it out quickly and quench it. If you have a fairly thick part, water or saltwater will work okay. If your part is thin, it is best to use mineral oil to cool it more slowly to avoid cracking it. Move it up and down and twist it at a moderate speed in the quenching solution. This procedure will cause the outside of the metal to become very hard, while the inside is softer and more resilient. This gives a good blend of hardness and toughness. [Too hard and it gets brittle, too soft and it won't take/keep an edge]
Thanks for this, something else for me to try now. :thumb:
 

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If you go to any discount store that sells tools you can get files very cheap or hit the flea market.

You need to anneal the file befire you grind it though.

Heat the entire file until a magnet no longer sticks to it and heat it a bit past that.

Stick the hot file into a bucket of vermiculite (get it at the garden store) the vermiculite must be dry. The file will cool very slowly and that is what you want so no peeking. Once cool you should be able to file it or gring it easily.

Shape however you want but keep dipping the blade into water, you don't want to see any colors forming on the blade.

Once finished, heat to non magnetic and dip into a can of motor oil. Then check with a file. If the file does not cut it than you ned to temper the blade. Clean off the scale and get down to bright metal. Start off in your oven at 350 degrees. The color you want on the steel is a light to dark straw color. Increase the oven temp 10 degrees at a time until you see this color. Go slow. No purples or blue's. If you do this correctly the blade should be about 55 to 60 rockwell and perfect hardness for blade.

You can use the above steps for any simple carbon steel and you will do ok.
 

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Most rail road spikes and rails in the U.S. are too low in carbon to harden properly and hold a good edge.Old auto leaf springs, if not to thick work well as does lawn mower blades. For your first few attempts try a high carbon low alloy steel. Check out some of the knife maker suppliers like Texas knifemaker`s supply or K&G finishing supplies for some thing like O1, 1095 or 5160
The ones in canada are much better then :thumb:
 
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