forge

All posts tagged forge

So, you want to forge knives… Well, I just started myself, only made a few blades so far. I have learned some information useful to beginners that might not be readily available online, or scattered all over the place. These lessons learned might save you some time, aggravation, even a few dollars.. Follow any advise here at your own risk, I am no expert and forging is inherently dangerous.

About forging: Forging is not just that, hammering a red-hot piece of steel into a blade. You need to consider what else comes into building a knife. A lot of time will be spent grinding, sharpening, and polishing. If using sand paper gives you unpleasant goosebumps, or you cringe at the thought of getting burned or cut, you might want to look into knitting. Heat treating is not as simple as plunging your steel in water. Some knowledge of metallurgy about different steels and what happens to them at different temperatures is a must. Annealing, normalizing, hardening and tempering are important phases in creating a blade. Then you need to make a handle, sheath, and sometimes apply different finishes. Building a knife is a whole process, forging is only part of it.

Forge: I started by building a charcoal forge. It worked, but it is slow and dirty, a pain in the ass, really. Sure, It only cost me $60, and I could have built a better one. Gas however is fast and clean. I bought a $200 forge on Ebay and never looked back. The next one will have a round shape though, and be covered with refractory cement instead of KAOWool. A round forge body creates vortexes resulting in a more even temperature and probably gas saving. With a hard refractory coating, you will never breathe dangerous ceramic fibers.. Coal is another good option, also dirty, but better in my opinion than charcoal. See my gas forge here.

Steels: Many beginners will try to find some scrap steel at the junkyard. You might get lucky finding what you want, but you might not. Spending hours hammering steel to find out that it won’t harden is no fun. I just ordered six 3/16 x 1” x 60” bars of 1080 from Admiral Steel for about $90 (with shipping)! That is enough to make from 30 to 40 large knives. Less than $3 per knife. Mystery steel is like mystery meat, you really don’t know what’s in it and most of the time, it doesn’t turn out to be that good. 1075-1080 is probably the best steel to start with. It is a simple steel, easy to heat treat and forge. You can temper it in a kitchen oven at 450F. Tool steels and other higher carbon steels require better temperature control and higher tempering temperatures, around 550-600F. It isn’t worth my time fishing for scrap in a junkyard. I would probably often have to discard half-finished blades, so the savings are really not significant enough. Buy good steel, pick one kind, learn it well, you’ll get consistent results allowing you to refine your process. More on steel selection.

Heat Treatment Anneal every time you stop working for the day. Normalize three times before hardening. Use a magnet to determine when the steel has turned to austenite and is non-magnetic. Go slightly higher, and let the blade soak for ten minutes at that temperature. If you forge or heat-treat too hot, your steel will decarbonize. Quench in warm oil (140 to 160F). Cold oil will actually not cool your blade as fast. Avoid motor oil, it’s too thick. Thin oil, such as ATF or thin mineral oil is better. Don’t move the blade sideways while it cools, but front and back. If you want to create a hamon by differential clay hardening, cover the back of the blade with a refractory like Satanite (1/8” thick layer). Temper immediately after hardening, three times one hour at 450F. If you use a different steel than 1060-1075-1080, find out what the numbers are, don’t just guess..

Anvil: I bought a cast iron anvil at Harbor Freight. It is way too soft! Here is when a trip to the junkyard might save you money. A 100Lbs hardened steel anvil will cost you $400 to $600. Find any piece of steel with a flat surface, as heavy as you can carry. Secure it to a solid base, so that you can forge standing up. Thanks to my friend Phil and his father at Seaboard Steel, I was able get a heavy piece of steel which originally was a jaw that grabs giant steel plates. It must be heat-treated because it is very hard. We welded it to an I-beam and a half-inch steel base.

Click on the image to enlarge..

Hammer and tongs: Almost any hammer will do (you might want to put a nice smooth finish on it’s face), but you need tongs to grab your blades. I started with a pair of wise-grips, but they are too short and awkward to use. Having a piece of red-hot steel fly out when you hit it is pretty scary. Don’t ask me how I know.. (well, I still have one scar on my ankle..) Start by forging tongues. It is easier than forging a blade, and you will need them anyway.

Click on the image to enlarge..

Not the best looking ones, but they work just fine..

Safety: Wear heavy leather gloves and clear eye protection (clear to see steel color). I have a welding jacket with leather sleeves that’s perfect for forging. Make sure nothing close to the forge can catch on fire. That includes your propane hose in particular! Wear a respirator when grinding or changing your ceramic fiber forge insulation. Don’t forget, you’re building knives, they can get really sharp! Blades can fly off your hands while grinding, specially when using buffing wheels. You must be conscious of safety all the time. You don’t want to end-up in the hospital or dead because of a hobby!

Information: It is easier to start with some help. Browse the following forums online:

Document you progress. You might discover that a blade you forged displays great characteristics after some use, and not remember how you made it..

I highly recommend Wayne Godard’s $50 Knife Shop book:


Wayne Goddard’s $50 Knife Shop, Revised
And Tim Lively’s DVD:


Knifemaking Unplugged

I will add to this article once in a while as I discover new tips or pitfalls to avoid. Anyone with more experience than myself, that’s almost anybody able to forge a decent knife at this time, please add any advise for beginners you may have in the comments section below. Many thanks to the members of bladeforums.com for their feedback on this article!

After weeks of consideration and research on the web, I finally decided to buy a katana. Not a cheap wall-hanger, but a practical sword, forged by hand and differentially hardened. I am very familiar with knives, even started to forge my own. Swords however are mostly unknown to me. Why would a grown man buy a sword you may ask, well, I have a few reasons, and they have nothing to do with the “cool” factor. Swords are not toys, but deadly weapons. I place them in the same category as handguns and rifles. I came to believe that they are one of the best home defense weapons available. My interest in knives came from the staggering number of designs found for such a simple, primary tool. Metallurgy, the forging and hardening processes have always fascinated me. I have barely scratched the surface of that art, but I can certainly appreciate the skills it takes to forge a blade longer than a few inches, then harden and temper it properly. My life-long interest and practice of the martial arts also influenced my decision. I have long ago found out that most Asian disciplines only work in their context. Russian Systema however works in any circumstances and can make use of any weapon. Give me a frying pan and I’ll be immediately efficient with it using Systema principles. A sword, though presenting some challenges, shouldn’t be too much trouble. Of course, I will use a dull one or bokken for practice. Other sword designs were interesting, but the Japanese katana in my opinion is the best sword. It is light, razor sharp, and simple in design. Nobody wears armor these days, so a heavier sword would make little sense. The way these swords are made is also fascinating. Even if you have no interest in swords, you can’t but admire the dedication and skills of Japanese sword-smiths in their pursuit of perfection. I never get tired of watching the following documentary from National Geographic:

[kml_flashembed movie="http://www.youtube.com/v/ko9vR2_ptlA" width="425" height="350" wmode="transparent" /]

I can’t pay three highly skilled artisans for three months to forge me a blade, so I have to accept some technological shortcuts. Modern steels like 9260 Silicon Alloy Carbon Spring Steel are even better than traditional tamahagane. It’s not traditional of course, but much cheaper. The folding process becomes superfluous, since the carbon content of modern steel is constant throughout the material. I would love a folded blade, but the cheapest ones, forged in China, start at around $1000. More than I am willing to spend for a first purchase. A San-Mai construction like my Cold Steel Master Tanto would be desirable too, but simply too expensive. There is one feature I really want however, and that is a differentially, clay-hardened blade. This process of covering the back of the blade with thick clay before quenching in water produces a very hard edge and a soft back (watch video above). This way, a sword will bend but not break, while still holding a razor-sharp edge. It also produces a visible line of hardness called the hamon. Most replicas have a fake one, acid-etched on the blade. I can’t accept “fake” anything, so my choice becomes fairly limited for an affordable real sword. Thanks to companies like CAS Hanwei and Cheness Inc., real forged blades from China are available, starting at around $160 for something that won’t come apart in your hands and take a lot of abuse before breaking. Shell-out $200 to $300 and you get a serious tool. My choice is the Kaze Ko-Katana. With a 21-inch blade, this katana is about seven inches shorter than a regular sword. These swords are also called chisa katanas, and are easier to use in tight places. Here is another review of the Kaze (watch the cutting test video). I got a 10% discount and ordered mine for less than $200, with free shipping.

Proceed to the full review

The charcoal forge was fun to build and use, but let’s face it, it takes forever to heat-up and it is pretty dirty. If I made another one, it would be more of a closed design to concentrate and conserve heat, and would have a good hand-cranked blower. So, I went on Ebay and shopped around to finally order a two-burner gas forge from CKForge for $199 plus $45 shipping. The design is basically a steel box opened on both ends and lined with insulation, with a firebrick on the bottom. A two-burner assembly is screwed on top. Connect a propane tank (I borrowed my housemate’s grill tank), and you’re ready to go. I wish the holes for the screws had been pre-drilled. Of course it is reasonable for the seller to assume that someone ordering a forge would own some kind of drill! My cheapo Chinese drill press from Harbor Freight did the job nicely. The forge is well built, with decent welds, no trouble at all, and it worked flawlessly right out of the box, but for the drilling.


[kml_flashembed movie="http://www.youtube.com/v/UK2cSd8FGUA" width="425" height="350" wmode="transparent" /]

Starting the forge was a walk in the park compared to my charcoal model. I grabbed the torch I use for Crème brûlée, lighted it, turned on the tank valve, then the regulator, barely, and finally the forge valve while sticking the flame inside the forge; it worked instantly. After what seemed a very short time, I had a red hot railroad spike on my anvil. A couple hours later I was finished shaping the blade! Not bad for a first timer, I thought, and so much faster than my charcoal home-made forge..
Forged Railroad Spike Knife

Forged Railroad Spike Knife


It looks a bit like a butter knife at this stage, but a little grinding will make the blade look a tad more “aggressive.” I traced a bevel line with a black marker, and a line where I will remove a bit of metal at the tip so that it isn’t so round. You can’t see it on the photo, but the edge is pretty close to it’s final shape, about 1/16th, 1/4” at the spine. The pommel looks a bit weird, but I didn’t know what else to do. A couple holes there for a lanyard will be nice. I flattened the ends so that it could be used like a hammer. At the end of my session, I brought the blade (now I can call it that!) to cherry-red hot and switched the gas off, leaving the knife to anneal (air-cool slowly to release stress) in the forge.
[warning]That small table you see under the forge on the video caught on fire after about an hour. So, if you get a similar gas forge, make sure nothing around it can ignite! Fortunately I had the garden hose handy.. And make sure the gas hose doesn’t touch the forge or dangle close to the openings. Now, that would be trouble![/warning]

June 24: Since I have to wait to get a decent grinder, I figured, what the hell, I’ll just make another one.. This time I am trying a double-edge knife with a twist in the handle. My friend Erin surprised me by setting up my anvil on a log, putting sheets of refractory material under the forge and installing a light above the whole setup. So, he’s drinking my beers right now and I am pretty happy with the installation. Here is a new video of me starting on the new blade:

[kml_flashembed movie="http://www.youtube.com/v/2tpYsC3GzAA" width="425" height="350" wmode="transparent" /]
And below, number two:
Second knife, double-edge with a twist

Second knife, double-edge with a twist


Next steps: Grinding, heat treatment, and sharpening. I might wrap the handle with fiberglass tape and epoxy, or opt for something more traditional. I am also thinking about parkerizing the handle and maybe part of the blade, but a nice polish would probably look better..

I finally decided to fire up the forge (see: Building a Forge and Making Knives, Part One), and try hammering a railroad spike into some kind of a knife. The only item I was missing was the air source. Forge blowers on Ebay are fairly expensive, from $150 to $250 average. Considering that I could buy a new gas forge for $300-400, there is no way I am spending that much at this time, with the little I know to make an informed decision. So, I dug out an air-bed manual pump from my storage unit and taped the hose to my forge intake pipe.

I gathered all my tools in the back yard: Forge, charcoal bag, hammer and anvil (from Harbor Freight), gloved, safety glasses, pliers, railroad spike, Zippo, lighter fluid and a bottle of water (to drink!). Now, before you read further, keep in mind that I have never done this before, and have not had any instruction on the matter, or advise from anyone, except the video mentioned in Part One…

I loaded up the forge with charcoal from a bag. First problem.. The chunks in the bag are too big. Fortunately, you can brake them easily with your hands, but it is just more work to do. We had some charcoal from a past bonfire, so I added some to the bowl and sprayed on a bit of lighter fluid. Well, let me tell you that it takes a little more to get the fire going. No problem.. There is enough palm frowns and twigs around to do the job.

Lighting up the forge.

Lighting up the forge.


With a little pumping, the charcoal soon caught on fire and crackled nicely. I put the railroad spike in and covered it with bits of charcoal to heat it up on all sides. And I pumped, and pumped, and pumped.. Now I can see how a good blower can make the job so much easier! After a while, the little bit of metal I could see was turning red at last! Time to grab it and hit it hard on the anvil.
[warning]Make sure nothing around you can catch on fire, including you and your clothing. Wear something on your head to protect your hair, and of course, safety glasses. When blowing air from under the fire, a lot of red hot ambers fly out![/warning]
[kml_flashembed movie="http://www.youtube.com/v/RBh1vsauR-0" width="425" height="350" wmode="transparent" /]

And this is why I should have bought a pair of real blacksmith tongues.. Not to mention that the forge gets really hot, and I burned my hands a few times under the gloves. My air source must not have been sufficient, because I couldn’t get the heat quite high enough, and only had a few hammer blows per heat to work with. I should have started by lengthening the spike instead of flattening the blade first. Now it will be harder for me to do it later. I bent the spike like for a drop-point blade to make up for the curving that will happen when I hammer the edge in. Hammer control is pretty difficult. Not only do you have to hit the blade where you want, but you also must keep the hammer face parallel to it at the same time. Right now I am just rough-shaping the knife, but later, any mistake will leave gouges on the metal that will be hard to correct. I also had to be careful to work on both sides equally to keep the blade aligned with the handle. As the edge became thinner, it had a tendency to fold on itself, so every three heats, I would hammer it gently back in. After four hours of efforts, this is what I had:
Side view.
Top view after four hours of work.

Top view after four hours of work.


Pretty slow work.. I will try to find some kind of electric blower for part three. Advise would be welcome, please use the comments. At least I am making progress. I want to get the blade as close as possible to it’s final shape before using any tools on it, most likely a file. If I really get into this hobby, I might get a gas forge, but I want to finish this one with th charcoal forge, just to be able to see what can be done without much technology and experience. If I get a usable knife, if not good looking, I will be pretty happy.

Continue to Part Three.

I finally decided to go ahead and build a charcoal forge to make knives out of railroad spikes, motorcycle chains, suspension springs and other junk steel. I have never done this before, but as always, I researched the subject thoroughly before diving in. My goal is to produce crude knives at first, without using any electricity. Using a grinder is thus not an option and the shape of the blade will have to be hammered as closely as possible to it’s final size. Forging a knife is one of those basic skills I think I ought to learn. Not that I expect to ever do it out of necessity. I want to experience the satisfaction of building the most basic tool with my own hands..

My first step was to find an expert on the web, and that turned out to be Tim Lively. His washtub forge seemed to fit my bill pretty well. Problem is, Home Depot didn’t have the washtub, so I settled on a large terra-cotta bowl. I hope that lining it with adobe (50/50 earthen clay and sand) like the washtub forge will prevent it from cracking.

To be able to reach forging and welding temperatures, you need to supply the burning charcoal with fresh air. I bought a bunch of pipes and fittings for that purpose:

Steel pipes assembly for forge air supply.

Steel pipes assembly for forge air supply.

I used a cheap drill press from Harbor Freight to drill 1/4 inch holes in the pipe that lays at the bottom of the bowl:

Drilling 1/4'' air holes in the top pipe assembly.

Drilling 1/4'' air holes in the top pipe assembly.

The assembled result looks pretty good:

Terra-cotta bowl and pipes assembly.

Terra-cotta bowl and pipes assembly.

Using galvanized pipes isn’t the brightest idea since they release toxic gases when heated. I’ll have to work upwind to avoid poisoning myself! I suggest anyone building a forge to use something else! Forge blowers on Ebay go for about $150 to $250; more than I care to spend for an old rusted piece of cast iron. I am not sure yet what I’ll use as an air supply. Any suggestions?

Now that I have the hardware, and while the adobe dries, I need to learn how to actually forge a blade. Fortunately, Tim Lively has an excellent DVD on the subject:

Mixing the sand and clay took forever. I had to use my Khukuri to chop fist-size blocks of clay, wet them and take little flakes out until the whole thing was gone. You have to be carefull not to add too much water. I tried to obtain the consistency of peanut butter. I started packing it under the pipe. Hopefully I didn’t leave any air bubbles in the adobe. Now the mix needs to dry for a few days.. I can see little cracks already, but it’s a forge I am making, not a teapot, so it doesn’t really matter, I’ll patch them up later. I also want to raise the sides a bit so that the charcoal stays in the middle, over the air holes.

Adobe drying in the bowl, aroud the pipe with air holes.

Adobe drying in the bowl, aroud the pipe with air holes.


Part two promises to be more interesting. The adobe will be dry and I will actually fire the forge up and try to hammer a railroad spike into a useable blade. I will film my efforts and post the video. Continue to Part 2.