Monday, December 13, 2010

The forging of a knife

First off, if the title didn't already clue you in, this is Gabe. I know, that fact and the actual titles content likely means a good portion of you will stop reading now. Fine, be that way.

For the rest of you, I thought I'd do a rambling post in case you find knife making interesting at all.

There are probably a lot of pictures I could post, if I had taken them, and if I had room to post them here. I have some pictures on my picasa that you can take a look at, although it isn't many.

One evening my cousin Pat told me he was going to take an old file he'd gotten on a garage sale, and forge it into a knife if he could. That struck me as being one of the best ways to spend an evening I'd heard in sometime, so I begged him to let me come. He accepted my invitation.

That was the beginning of my knife making hobby. And I did manage to pound out a reasonable looking knife, do some kind of heat treatment to it, and make a handle. I even got it sharp enough to scrape a few hairs off my arm. Then the tip failed when it got used as a prybar, and it now is pointless.

I began to do some reading about knives, and the forging of them, and discovered that there was a lot to learn. I got some "high carbon" railroad spikes and began forging knives out of them. That was fun an certainly gave me some good experience, but the steel was pretty soft for making a useful knife.

After doing quite a bit more research about knives and steels used to make knives, I realized that probably the best steel I could use to make knives was 1084. The 10 series steel is a simple carbon steel. The second number (84) refers to the amount of carbon in the steel. 1084 is approximately .084 percent carbon. I'm sure I'm boring most of you here, but if anyone is interested in this, I'm giving you enough info for a start point. The reasons 1084 is good for a limited equipment, part time forger are mainly related to the heat treatment. Heat treat is the single most important thing in making a usable knife.

So the knife making process for me right now is as follows. Get a piece of my 1084 bar stock. It measures 3/16 X 1"X whatever length. Start up my coal fired forge, which is an old brake drum with forced air (from the air compressor) blowing up through the bottom. Or the 1800's forge that has a hand crank fan. That one needs some more work. I have an anvil that I am borrowing right now, and would like to find one of my own. My 3 hammers and 1 hand forged set of tongs complete my forging tools.

The actual forging is pretty self explanatory. I heat the metal to red heat (not too hot, if it sparks it's overheated, and overheated steel is not good), and hammer the steel to the basic blade and handle shape and thickness I want. That varies. Working hot steel is like working play dough, except it's a lot harder. It does what the laws of physics say it will do when the hammer hits it. If you don't know what the laws of physics say it will do, it may surprise you what direction it grows. Directional hammer blows have a huge impact (pun alert) on the direction the steel will shift. Forging is all about rearranging the metal in the form you want, not removing what you don't need.

After I have a basic shape and the right thickness, I get a smaller hammer and work at smoothing the metal as much as possible, so that it requires less work later. Refining the steels surface with a small hammer on the anvil is far more enjoyable than filing it off later by hand.

Next I take it to the grinder, and grind away the inevitable bumps along the edges to get the profile I want. It's a good idea to have a pattern marked on the blade, since you can overdo it and mess up pretty easily. After that, I file the surface until all the low spots are gone (unless I want it to have a hand-forged hammer-marked appearance). Then it's time to sand it until it shines. You can get it to a mirror finish if you want to, but it still has to be heated up again for tempering.

1084 steel is easy to heat treat. You need a magnet, a torch or forge, and vegetable oil. I don't recommend using water to quench 1084, although some folks might do it. Here's what you do. You heat the steel evenly, and slowly until it becomes non-magnetic. That's what the magnet was for. At this point (I need to know just when it becomes nonmagnetic, so I check frequently)the steel needs to rise another 100 degrees or so. I can see color in it now, so I just bringing it up a shade or two in color. That will be around 1550 degrees Fahrenheit. The next part happens quicker than I can explain. The steel is taken from the forge or torch, and plunged into the quenching liquid. This happens quickly, because you've got about 3/4 of a second to get that steel from the 1500 degrees or so, to below 900 degrees. If it doesn't happen that fast, you won't get good hardening. After the quench, when the steel is back to room temp, I take a file (the same one I used before) and check the steel. If the file skates over the steel and won't cut into it, I got it hardened correctly. Next I temper for two one-hour periods at 400 degrees in the oven, letting it come down to room temp in between.

After that, it's time to make a handle, and use the belt sander to grind the bevel in the knife edge. Of course, that must be done carefully, since if the knife heats up too much it will ruin the heat treatment. So I keep a glass of water handy to dip the knife in whenever it begins to get warm.

The handle can be made many different ways. The last knife I made (the big chopper that's halfway through the golf ball) only has paracord wrapped around the handle. It's simple but effective. My neck knife has walnut scales glued and pinned on each side of the full tang.

Okay, if anyone actually read all through until here, you must be dedicated. It is a long and complicated process, and I've only touched on the main and most important points. There's a lot more I could have said, and a lot more that I have to learn yet. But its been fun so far, and I'm enjoying learning what has become something of a lost art. For anyone out there who is interested in learning more about forging knives, there are many excellent resources out there, including the internet.

Wrapping this up, here are a few pictures of my knives....

This is my favorite railroad spike knife. I had a low spot in the blade I couldn't get out without making it too thin, so I left it there. That's why there's a "blemish" in the blade near the heel.

Here's a collection some of my first knives. All of these began as railroad spikes.

Below is my "neck knife". It's the one I carry most, and use for anything I'd use pocket knife. It's forged from 1084 steel, and I try to keep it sharp enough to shave with, although I'd hate to try.
At the bottom is my latest knife. I call it my 'beast'. It's about 13" over all with a 9" blade. I made it for the sole purpose of having a knife of 1084 steel that I could use and abuse with the intention of testing its limits (and thus mine). The heat treat on it is slightly different than I described above. It's treated so as to have a soft and flexible (that term is relative) spine, and a hardened edge that will take and hold a sharp edge. It's sharpened at a higher angle so as to hold its edge better when it's doing things like chopping through two by fours, being driven through firewood to split it, and chopping into a golf ball at (my) full strength. None of those things have broken it yet, not that I particularly want to break it. That's not a faked picture, that is how far it went into the golf ball with one swing.
I have another creation that I can't show in pictures until after Christmas....

So as you may have guessed, I'm enjoying myself. If anyone needs a knife made just let me know about it and maybe we can work something out! I can use the experience, but as of now I surely wouldn't guarantee my work!

To all you who skipped from the first paragraph to the pictures, maybe we can post something more interesting next time!