Almost embarrassed to ask

[verndahl]

I've always been interested in knife making and am in the process of taking the next step. With a limited budget i need to start small (plus i don't have any plans of making them to sell so it doesn't make sense to invest a lot of money). What i am aiming for is building a small forge that i can heat with a propane torch, and for now trying to use whatever high carbon steel i can scrounge for free. So, if i started with a industrial hacksaw blade (which is hard but my experiments show doesn't hold a good knife edge) do i need to anneal it first or can i harden it from it's already hard condition?

 

[32t]

For learning and a small job buy known steel.

The time and effort is the same as with the unknown and the chances of success are much greater.

And the price difference is minimal!

 

[RezDog]

I do not have a great amount of experience, but I did not find that steel is expensive.

 

[Robbie d]

While it may seem that you are not investing a lot of money in making a can forge, in my experience, you'll end up spending the same as if you made one from a dedicated forge burner. As the others have said, buy some steel, a bar of simple high carbon steel shouldn't be that expensive.
Things like leaf springs, coil springs, and torsion bars seem to be a better reliable source of hardenable steel if you are looking for free. Modern tool blades are seldom made of reliably good steel.

 

[verndahl]

Thanks for your replies. i'll give it some more thought.

 

[Bruno]

One of the most dependable sources of good steel are old files. They are high carbon, harden well and do not have issues such as fatigue cracks that spring steel can have.

There are a couple of online places where you can order good knife steel. If you are not looking for a specific type, they often have very dependable choices. For example there is a German guy close to me where I can buy a lot of steel easily. His 15N20 is 4 euros for a flat bar, and his 52100 is 8 euros for a flat bar. The huge benefit is that it is already soft when you get it so easy to work with, and you can heat treat it more easily.

If you do go with salvage steel, try to find old files.

 

[Bruno]

As to forging: any heavy chunk of steel can be used as an anvil. And if you want to forge cheap, a charcoal forge is also an option. This is my old charcoal forge. I made a lot of complex pieces using just charcoal. It is generally a bit cheaper to run charcoal, depending on how much you need to pay for it of course.

 

[verndahl]

Thanks Bruno, Is there a type of new steel that would be forgiving in tempering if say, (don't laugh) all i had to use was my home oven? (if it's possible). And could it be used if i want to make a usable razor? I was actually thinking of making some type of frame back to avoid any type of smything at this point.

 

[Bruno]

Assuming you work with annealled (soft) knife steel, there are 2 heatings to consider.

The first is hardening. Hardening is when you heat a piece of steel with a high enough carbon content to above 760 degrees centigrade, and then cool down suddenly by dunking it (quenching) in warm vegetable oil or water, depending on the steel type. At 760, the carbon in the steel dissolves, and the steel changes crystalline structure to austenite. cooling down rapidly 'traps' the dissolved carbon and the steel becomes martensite.

At this point, the steel is very hard, but also very brittle. If you would drop it on the floor, it would shatter because the quenching process introduces a lot of stresses. That is fixed by putting the piece in a normal oven at about 200 degrees centigrade. The stresses will disappear and the blade will be strong.

You can temper in a normal home oven, but the temperature for hardening needs to be above 760.

However, that is fairly trivial. A simple charcoal fire and a hairdryer can make you a fire that is hot enough. When I did not have a kiln, I used to heat my blades by putting a piece of iron pipe in a charcoal fire, and then heating it until it glows orange. Then you can put the blade in the pipe, and wait for it to reach the temperature. While it is possible to use a magnet to help you determine the correct temperature because magnetism disappears at that point, I never liked it because steel will stay non magnetic for a while even if the temperature drops again.

Color perception can be used if you don't have a thermocouple or something like that to measure the temperature. If you use color, I'd say a dull orange. Color is different for anyone, and depends on lighting conditions. But you can always do a tryout with a couple of strips of your steel and hardening them. If you can snap them in a vise and they break easily, that means they were hard and that part of the process is ok.

 

[cangooner]

My few thoughts in addition to what has been written above:

1 - go for it! If you're at all interested, then it will totally be worth the journey.
2 - consider making a proper burner as Robbie d suggested. This can be done for very little cost from plumbing parts found at your local hardware store. Google and youtube is your friend on this.
3 - known steel is of course ideal. But if you're messing around for yourself, then there are other options too. Spring steel from cars/trucks can make an excellent knife blade. Most often it is a type of steel called 5160. If the spring is used, it can contain micro-fractures, so I would never use a used spring for something I wanted to sell. For a knife intended for my own personal use however, I'd have no problem using it.
4 - you can spend a TON of money on this hobby, but you *really* do not need to. The hammer I still most often use (3 lb cross pein) was bought at a Harbor Freight for a few bucks. I built my forge and burners myself. To start, you can use pliers for tongs (and make your own tongs for very little cost too). And as Bruno said, you don't need a fancy anvil. Don't get me wrong. I wish I had a nice new big anvil (mine is a bit small and beat up, but works just fine), forging press, power hammer, etc., but I get along OK without them. Also, the price of anvils has absolutely skyrocketed recently. All the more reason to consider a length of rail or some other alternative. At least to start.
5 - it is possible to really overthink this stuff too. Get good high-carbon steel, get it hot, whack it into shape, heat treat it, temper it, affix a handle if needed, and enjoy.
6 - if your first attempt is anything like mine, it will be uuuuuuugly! And I had some blacksmithing experience prior to bladesmithing. Don't worry about that. It will get better, and you'll have a load of fun

 

[cangooner]

This doesn't really address your original question, but there are good thoughts re starting out here:

 

[Randolph Tuttle]

The way I started out was by meeting an old knifemaker who helped me learn a lot. He is now 97 years old !
Another great resource are local blacksmithing groups. Look them up, attend a meeting or two.
Another resource are local knife clubs.
I also agree with using known steels or old files and making your own forge.

Just my 2¢

 

[Mike Blue]

You are receiving a lot of good advice. If we all tell you the same thing about a part of the process, it's probably good information. If you get diverging opinions from everyone, keep looking and learning.

Industrial hack saws are usually a chrome moly alloy on the back of the blade and some form of high speed steel like M2 or M42 just on the teeth. They are not very good for knife blades. Stick to simple steels. Old files are a great source of known material. When in doubt, get it non magnetic, quench it in water and break it.

There is also spark testing as a quick and dirty and fairly accurate means to estimate carbon and alloy content for "found" materials that don't come with a spec sheet.

 

[Mike Blue]

You're not obligated to forge out a blade.

The whole process ends by being a knifemaker not necessarily a forger. You still have to shape the steel into a knife shape with some sort of abrasion. I would recommend doing that before heat treatment.

 

[verndahl]

Very good advice indeed. Good to know about the hacksaw blade steel. I'm going to start with just some simple grinding and heat treating before i get into much forging as i don't have the space or proper tools as of yet. I'll certainly have more questions i'm sure.