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How to temper steel for spark/fire-making?
- Thread starter Return of the J.D.
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- Nov 29, 2005
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Oh--one more question: any problems with (or different techniques for) using other kinds of oil, like veg oil or crisco or lard?
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- Aug 3, 2004
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I tried olive oil on something I was tinkering with. Two things happened: the oil wasn't hot so it just boiled right off the blade and didn't quench (hence heating up the oil), two the oil wasn't thick enough I think. YMMV but that's what I gathered from a little tinkering.
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- May 18, 2005
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J.D. From info I gleaned on another forum when I asked this same question...
Get the file hot to cherry red and let cool slowly to anneal the metal to make it workable (If going for stock removal), or simply shape with a hammer whilst at cherry red, re-heating whenever required to keep it soft until you have the shape you want.
When the file has become the shape and size that you want for your "steel" simply heat to a brighter red, even to yellow and quench in water, (moving it about so that it doesn't become surrounded by steam bubbles which slow the cooling effect.)
This quench WILL leave the metal pretty brittle but it will be very hard and will therefore throw good sparks off a natural flint. A flint-and-steel "steel" should not break under normal use however brittle-hard you manage to make it, and the harder it is the better it will work.
The reason that knife makers quench their blades in heated oil rather than water is that it actually cools the blade quicker than using unheated oil. By pre-heating the oil it is made to be more fluid. This in turn makes it easier for the oil to flow around the blade and take the heat away from it than if it were cold and therefore less viscous. The higher boiling point of oil compared to water means that the blade is less likely to become surrounded by bubbles of steam (which actually slow down the cooling effect of the liquid) and allow for the quench to be done with far greater control.
N.b. This info is as I understand it from what others (who's opinion I trust) have told me now that I am starting to get the bits together to make my own forge and start heat treating my own blades and "steels". If any of it is horrendously wrong it simply means that I misunderstood the info I was given, and I'd be grateful if someone who knows more on the matter would correct me.
Get the file hot to cherry red and let cool slowly to anneal the metal to make it workable (If going for stock removal), or simply shape with a hammer whilst at cherry red, re-heating whenever required to keep it soft until you have the shape you want.
When the file has become the shape and size that you want for your "steel" simply heat to a brighter red, even to yellow and quench in water, (moving it about so that it doesn't become surrounded by steam bubbles which slow the cooling effect.)
This quench WILL leave the metal pretty brittle but it will be very hard and will therefore throw good sparks off a natural flint. A flint-and-steel "steel" should not break under normal use however brittle-hard you manage to make it, and the harder it is the better it will work.
The reason that knife makers quench their blades in heated oil rather than water is that it actually cools the blade quicker than using unheated oil. By pre-heating the oil it is made to be more fluid. This in turn makes it easier for the oil to flow around the blade and take the heat away from it than if it were cold and therefore less viscous. The higher boiling point of oil compared to water means that the blade is less likely to become surrounded by bubbles of steam (which actually slow down the cooling effect of the liquid) and allow for the quench to be done with far greater control.
N.b. This info is as I understand it from what others (who's opinion I trust) have told me now that I am starting to get the bits together to make my own forge and start heat treating my own blades and "steels". If any of it is horrendously wrong it simply means that I misunderstood the info I was given, and I'd be grateful if someone who knows more on the matter would correct me.
Longstrider is spot on about the heated oil. When you heat the liquid you`re quenching with, it actually cools the steel quicker. Mind you, that heating the liquid isn`t really necessary when you`re just beginning to experiment with hot steel. If you get something wrong, just scratch it up as experience, figure out what went wrong, and jump right back in the proverbial saddle.
About different oily substances for hardening, i`ve heard and read about all kinds. The most commonly used seems to be automotive oil of some sort, mind you, not diesel. Don`t know if the diesel would just burst into flames, which is something you wouldn`t want.
The general rule however, is that if the oily substance, be it gear oil, olive oil, lard, crisco, frying oil from your local fastfood place, if it`s liquid, you can use it. If you have to heat it to make it liquid, you can probably still use it.
The only way to be sure, is to give it a try. But try it safely. Don`t put your head over the bucket of lard, in case it flames up. Suddenly you`ll find yourself missing an eyebrow and probably with some 3rd degree burns. Not nice.
Xanax: You`ve got it pretty much right with the process, but there are some mixups.
Process:
Heat to orange-red,
Shape,
Heat to yellow-orange (Or until non-magnetic. Non-magnetic means that the steel is at what is known as 'critical' which means that it is possible to harden it. Check with a magnet. If it sticks, it`s still magnetic.)
Dunk the steel into water or oil.
DO NOT REHEAT!
If you want to temper it, i`d suggest to do it in a kitchen oven, as it gives you a much greater control over temperatures, than over a flame or coals.
200-300°Fahrenheit for about an hour would probably be about right. Again, the only way to figure out would be to experiment.
To normalize steel, you heat it to a orange-red color, and just bury it into ashes.
As my latest experiments took place in a woodburning stove, i would simply heat the steel to the color i want, then just bury the steel down in the ashes below the fire. Then wait for the fire to burn out. That`d give the steel the most stabilized normalizing i could ever give it with the simple tools i like to use.
And yes, you usually need a source of forced air to make steel non-magnetic, or even heating it up beyond a brownish-red could be difficult.
If you have a woodburning stove, it could be possible to use the draft-effect in the stove to heat the steel up.
Other than that, if you have a tarp or some kind of waterproof fabric, it wouldn`t be too hard to make an improvised blower of some kind.
I can try to make some simple drawings of the kinds of blowers i`m thinking about, if anyone is curious.
Hopefully i managed to answer some questions.
About different oily substances for hardening, i`ve heard and read about all kinds. The most commonly used seems to be automotive oil of some sort, mind you, not diesel. Don`t know if the diesel would just burst into flames, which is something you wouldn`t want.
The general rule however, is that if the oily substance, be it gear oil, olive oil, lard, crisco, frying oil from your local fastfood place, if it`s liquid, you can use it. If you have to heat it to make it liquid, you can probably still use it.
The only way to be sure, is to give it a try. But try it safely. Don`t put your head over the bucket of lard, in case it flames up. Suddenly you`ll find yourself missing an eyebrow and probably with some 3rd degree burns. Not nice.
Xanax: You`ve got it pretty much right with the process, but there are some mixups.
Process:
Heat to orange-red,
Shape,
Heat to yellow-orange (Or until non-magnetic. Non-magnetic means that the steel is at what is known as 'critical' which means that it is possible to harden it. Check with a magnet. If it sticks, it`s still magnetic.)
Dunk the steel into water or oil.
DO NOT REHEAT!
If you want to temper it, i`d suggest to do it in a kitchen oven, as it gives you a much greater control over temperatures, than over a flame or coals.
200-300°Fahrenheit for about an hour would probably be about right. Again, the only way to figure out would be to experiment.
To normalize steel, you heat it to a orange-red color, and just bury it into ashes.
As my latest experiments took place in a woodburning stove, i would simply heat the steel to the color i want, then just bury the steel down in the ashes below the fire. Then wait for the fire to burn out. That`d give the steel the most stabilized normalizing i could ever give it with the simple tools i like to use.
And yes, you usually need a source of forced air to make steel non-magnetic, or even heating it up beyond a brownish-red could be difficult.
If you have a woodburning stove, it could be possible to use the draft-effect in the stove to heat the steel up.
Other than that, if you have a tarp or some kind of waterproof fabric, it wouldn`t be too hard to make an improvised blower of some kind.
I can try to make some simple drawings of the kinds of blowers i`m thinking about, if anyone is curious.
Hopefully i managed to answer some questions.
- Joined
- Nov 29, 2005
- Messages
- 887
Excellent; thanks, guys! Aarya, I'd gladly see your idea about an improvised blower (though I've had some success with such improvisations as a $10 hand-pump inflator from Wal-Mart)--it's always good to see more ideas.
Longstrider: you're in Milton Keynes, eh? Nice hearing from you. Spent a couple of years in Oxfordshire back in the early '90s; nice land thereabouts.
Longstrider: you're in Milton Keynes, eh? Nice hearing from you. Spent a couple of years in Oxfordshire back in the early '90s; nice land thereabouts.
My design is like this one
except that it`s made from a plastic garbage bag instead of animal skin.
The page that i found that image, also has quite a bit of stuff on primitive blacksmithing. I just read about something called concertina bellows, and i`m in the process of googling this up now.
Also, i just got some new ideas, so i`ll be back with those later on.
The page that i found that image, also has quite a bit of stuff on primitive blacksmithing. I just read about something called concertina bellows, and i`m in the process of googling this up now.
Also, i just got some new ideas, so i`ll be back with those later on.
i am not a knife maker or blacksmith, but the idea of flint and steel is to chip off small pieces of the steel and that is the spark, unlike the ferro rod - where the rod is chipped off to make the spark. i believe that the ferro sparks are 5000 degrees, but the steel sparks are about 800 degrees, that is why you need char cloth to catch the low temp sparks.
given that i would think that you would want a brittle piece of high carbon steel to make the sparks from flint or chert. i am not sure if you want to draw the steel, just heat it to nonmagnetic and quench in oil to make it brittle and hard. that is why the files work well for this--because the steel is hard and brittle so it chips off easily. maybe i am wrong on this, but seems like this is how you would want to go.
alex
given that i would think that you would want a brittle piece of high carbon steel to make the sparks from flint or chert. i am not sure if you want to draw the steel, just heat it to nonmagnetic and quench in oil to make it brittle and hard. that is why the files work well for this--because the steel is hard and brittle so it chips off easily. maybe i am wrong on this, but seems like this is how you would want to go.
alex
It's late so I didn't read all the posts but I'll tell you what has worked for me. Get an old garage door spring, the larger size, about 2" in diameter. Cut each coil so you end up with a circle of metal. Place in your forge-flame until it is orange and straighten. Reheat and curl the ends into an elongtaed c-shape to fit your hand. Reheat and check for straightness. Drop into water. Done. I can tell you from experience these work very well and you can make a bunch in a short time to give away or sell for $6-$7. Have fun.
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- Dec 20, 2005
- Messages
- 1,523
Ragweed forge sells purpose made fire strikers for 10-11 bucks. As for the large ferocermium rod, Exploration products sells the 3/8" x 4" rod for $16.00. I use a chunk of hacksaw blade, and it seems to work pretty darn good.
