How do I heat treat a knife, simply and cheaply?

search on the Fainter Trails forum for Foxwalk's 'Great Knife Build Along' - he has very good instructions for how to use a backyard fire and a magnet for treating a farrier file knife. Other people will advise you better than me... but just make sure your steel will work with simple 'bring it to non-magnetic' methods.
 
I agree with Mossanimal....a good bed of coals from a campfire would be more even heating. You could speed it up a bit by usng a hair dryer to make a blower. get a length of metal pipe long enough to keep the dryer well away from the fire, duck tape the dryer to the end of the pipe...stick the other end of the pipe in the coals and turn on the dryer.....it will give you a decent temporary forge.
 
I have hardened a few blades out of 1084 using torches. Just for another idea for you, I use two torches. One sitting on the ground, and one in my left hand (while holding the blade with my right) I can use two torches to maximize the evenness of my heating along the edge, and can prevent overheating by moving either the blade from the bottom torch, or moving the top torch.

Once I have the blade close to the right temp (reaching non-magnetic) I hold both torches aimed at the same spot, and I push and pull the blade through the heat (tip to plunge, tip to plunge) until it is a very uniform color of orange.

Then I quench the blade into an ammo can filled with about 120 degrees canola oil. These blades all skate files before tempering, then I temper them at around 400 degrees for an hour or two.


Of course this is just how I have done it at home, your mileage may vary if you decide to do this. I hardened my first 2 blades out of O1 using this method, and although it was not held at temp for 20 minutes, they got hard (Not the full hardness that O1 can reach with proper equipment), which was good enough for me.
 
Calaustria said:
Yeah, I might even do it with a fire, seeing as it would probably heat the knife more evenly than I could with a torch. What do the rest of you think?

I'd also need to rotate and flip the knife in the oven every 15 minutes since its not a convection oven.
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I don't think it matters if the oven is convection or not, mine is not convection. I would not take the knife out and rotate it every 15mins just because the oven would lose it's temp everytime you opened the door. You want to maintain a consistent temperature in the oven. My first few knives were done in a simple backyard fire and they turned out pretty good. Maybe check out Youtube and Greenepete's Knifemaking Basics for some simple backyard steps to making a knife.
 
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This is a very cool thread alot of information. But I don't know one type of steel from the next unless it is marked. For instance what is regular old bar stock steel? Like you would use in basic fabrication shops. The other types of steel are easy to find out what they are because they are not common to find. Just wondering. Great thread. thanks. John
 
There's not really any specific regular old barstock steel. Most likely what you see in fab shops and at Lowes is low carbon steel, maybe called weld steel. It isn't appropriate for knife making because of it's low carbon content.

It is important to know what specific steel you are using as this determines the appropriate heat treatment. Each steel has a specific heat treatment. Taking the regular old "back-yard" neo-tribal Rambo heat treatment and applying it across the board just doesn't work. Keep that in mind. If you don't know what the steel is, then you'll have to guess, experiment with your heat treatment, and try to find the best combo to harden the steel appropriately. It's just trial and error that way, so it's often recommended, to save time and effort and produce the best blade possible, to use known steel.

As for the original question, I still say you're doing O1 a big disservice by heat treating it inadequately. It has the potential to be a great knife steel if treated correctly. 1084 steel is better suited to torch heat treating. Like has been said, you'll probably get the O1 hard, and it may make a servicable knife, but it's not going to be at its best potential. So, use this type of experimentation as a learning experience. Try not to overheat the steel if you're using a fire pit. It's easy to burn the tip or thinner areas of the blade as you have no means to control the temperature in a coal fire without experience in how to manage it.

As for quench, edge fist, spine first, or tip first will work just fine for the most part. Just make sure you go in smoothly and evenly, and agitate tip-to-butt or spine-to-edge once it's in the oil. Agitate until vapors stop forming off the hot blade if you just lift the butt above the oil's surface. And if you're using off-the-shelf household oils like canola or the like, it should be pre-heated to around 130F or so. Leave the blade in the oil until it's oil temp and then take it out, wipe it off and file test it. Then straight into the tempering oven.

--nathan
 
silver_pilate thank you for the information. What I meant to ask was this. I have seen alot of differant steels here made into knives all had a #1084 or 01 and so on. I was wondering what weld steel is or if it even has a #. Just trying to learn more about the differant types of steel used here. John
 
silver_pilate said:
There's not really any specific regular old barstock steel. Most likely what you see in fab shops and at Lowes is low carbon steel, maybe called weld steel. It isn't appropriate for knife making because of it's low carbon content.

It is important to know what specific steel you are using as this determines the appropriate heat treatment. Each steel has a specific heat treatment. Taking the regular old "back-yard" neo-tribal Rambo heat treatment and applying it across the board just doesn't work. Keep that in mind. If you don't know what the steel is, then you'll have to guess, experiment with your heat treatment, and try to find the best combo to harden the steel appropriately. It's just trial and error that way, so it's often recommended, to save time and effort and produce the best blade possible, to use known steel.

As for the original question, I still say you're doing O1 a big disservice by heat treating it inadequately. It has the potential to be a great knife steel if treated correctly. 1084 steel is better suited to torch heat treating. Like has been said, you'll probably get the O1 hard, and it may make a servicable knife, but it's not going to be at its best potential. So, use this type of experimentation as a learning experience. Try not to overheat the steel if you're using a fire pit. It's easy to burn the tip or thinner areas of the blade as you have no means to control the temperature in a coal fire without experience in how to manage it.

As for quench, edge fist, spine first, or tip first will work just fine for the most part. Just make sure you go in smoothly and evenly, and agitate tip-to-butt or spine-to-edge once it's in the oil. Agitate until vapors stop forming off the hot blade if you just lift the butt above the oil's surface. And if you're using off-the-shelf household oils like canola or the like, it should be pre-heated to around 130F or so. Leave the blade in the oil until it's oil temp and then take it out, wipe it off and file test it. Then straight into the tempering oven.

--nathan
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Good advice. I would be interested to see actually how much difference backyard heat treating with a torch or whatever versus professional heat treating makes. Anyone have any actual knife comparisons or performance test evaluations? Like say if a person put an O1 blade simply treated with a torch next to one treated with a specially controlled oven, how much difference would there be. Not knowing which was which would it be that easy to tell the difference?
 
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Any of you guys ever tried tempering with a heat gun?
easiest way I have found to get a nice even straw accross the edge.
 
ill sell you a SUPERFORGE kit one time special $500!!!!! but ill warn you at this price you dont get the teflon pan:thumbup::D:thumbup::D
 
I would use the torch, less likely for oxidization to attack your steel than a haphazard wood fire. Use a fair sized brazing tip and run the flame a little fuel rich. keep the flame near the spine and away from the tip. Let the heat and orange color flow to the edge and the tip. Don't hurry it, you can bull the flame back a bit to slow things down as you reach higher temps. O1 should be about 1500f which is the temperature that non iodized salt melts. When you quench it I would go point first, or edge first. I think you are confusing flat with horizontal edge first. Flat sucks.
Temper at 400f in your oven. No need to turn it. It will get hot all the way thru
 
A magnet only tells you when the steel is non-magnetic. THAT is not the time to quench. You need about 75° more heat, which would be about two shades of red hotter than non-magnetic. A bright tangerine to most eyes.
You might have more control with a charcole fire, likely better than a torch, but you will have to carefully monitor whats happening. Pay close attention to the point. It will heat faster than the rest.
 
silver_pilate thank you. I just wondered if it had a # to. Thanks for the information. John
 
I know this isn't ideal but I use my wood stove until I can get a real HT oven. I make sure I get a good bunch of hardwood coals going, then I get a piece of hardwood burning on each side of those coals a couple of inches apart. Then, I open the vent on the front of my stove to get a good draft sucking through the coals. When it's going good, I'll put the knife in, edge down. I put a scrap piece of 01 in last night to test. It was 1"x4"x3/16" and in about 3 minutes it didn't stick to the magnet. It works pretty good for now but it's not real accurate. I have tried a hibachi with a light fan on the coals but it seemed like the impurities in the charcoal left the steel with some scars or light grooves.
 
R.C., I can tell you that I've done it both ways. When I first started out, I had some O1 and heat treated using an uncontrolled one brick forge and a quench in canola oil. I had problems with consistency in hardening because of uneven heating. In other words, some areas of the edge held up pretty well, others didn't and rolled with chopping or dulled with cutting. When I built my oven, I heat treated O1 properly, and there was as big difference in performance. The heating was for all intents and purposes completely even, and the edge was full-hard. The knives held their edges longer and stood up to more abuse than any I had done in my one-brick forge.

That's not to say it can't be done, but you need good control of temperature so you get even heating without OVERheating excessively. And you will get better results with a hold of at least 5 minutes (15-20 is better) which is hard to do at proper temp in a fire pit or a forge or with a torch.

--nathan
 
Roterm, you can easily draw on the color using a heat gun, but the thing about tempering is that it's not *just* the temperature. Good tempering is a process of time and temperature. A minute, or a few seconds, at 400 degrees will not completely temper the blade. It will likely decrease hardness, but you're not getting the full stress relief and conversion of retained austenite that you would with a 2 hour temper. For O1, I always temper 2 hours, 3 times.

--nathan
 
i heat treat all of my knives with a torch. if the blade is around 6" long it can be done real easy. i found out its best to turn down the oxygen as low as possible while stil maintaining a nice gentle blue flame about 5" to 6" long. you dont want it blasting or noisy. you dont want any yellow sparks coming off the steel, if there is you have the torch too hot and or too close.

do your heat treating in as low a light as possible. wait till late evening if you have to so you can see the true color. its easy to over heat the blade if you do it in a lighted room since it has to get hotter before you see the orange color. have someone hold the blade edge up while you move the torch along the length of the blade. dont worry about heating it up quickly, just do it evenly.

for me to heat up a 6" blade made from 3/16" thick, 1 1/2" wide 1075 takes me about 7-8 minutes total. i hold the color i want for at least 2 minutes before quenching in slightly warm (used will even work) canola oil. never put the blade in the oil flat or it will bend. always go straight down with the handle up and never move the blade side to side, always move from spine to edge if anything.

i get a rc between 63-65. test the blade with a file. if the file cuts the edge its too soft and needs redone. here are 2 knives i heat treated so you can see what you should end up with. there should be very little scale that wipes off easy on the edge if done properly. above the heat line the scale wont come off easy.
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I think Richard hit the main point of heat treating with a torch. It can be done, but the blade must be brought to temp slowly and evenly, and held there. When you quench, you need to make sure the heat is evenly drawn on the blade.

And remember guys, what works well for 1075 may or may not work well for other steels.

--nathan
 
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