Or how to cook a cat
Foreword: Recently there have been several requests for basic instructions on making a knife. Knifemaking like blacksmithing is 80% mind and 20% muscle. If you think you can make a knife you can, if you think you can’t make a knife YOU CAN’T. I continually hear people lament that “I can’t forge weld”, “I can’t make a knife”, “I can’t do this or I can’t do that”. Every time I hear someone say I can’t, I reflect on the words of Bill Epps: “I remember old I Can’t, the dumb SOB died in the poor house.” You must have confidence in yourself and your abilities before you can do anything well so park the negative attitude at the door. You can and you will make a knife. It is really not that hard. If you can forge steel, you can make a knife.
There are numerous schools around the country that will take a good chunk of your change and teach you the basics of knifemaking. They are reputable establishments and much can be learned from them. If your intentions are to go into business making knives by all means avail yourself of the finest education in the process that you can afford. But remember it will be your ability to apply what you have learned that will determine the quality of the finished product. Any instruction you get will shorten the learning curve and allow you to produce a better product sooner. If, on the other hand, your intentions are to just make a few knives for yourself and family or friends, you may not want to invest the time and money in that much education. I am by no means implying that it would be a waste of your time and money, what I am trying to say is that you don’t need a PHD to flip burgers. You will however, need to avail yourself of a little knowledge about various types of steel that make good blades and how to properly handle that steel to produce a quality blade. The reason that I can do many of the things I do isn’t because I am particularly brilliant or talented, it is because I am too dumb to know I can’t.
This article is by no means meant to be the definitive text on knifemaking. There are other knife makers that will read it and tell you that I don’t know my Gluteus Maximums from Aha (for those of you who don’t remember Biology and Science, the Gluteus Maximums are the largest muscle in the backside and Aha if a form of lava.) (Now can you figure it out)? They will probably be more or less correct in their opinion, but just as there is more than one way to skin a cat, there is more than one way to make a “cat skinner”. It used to be that knife makers were few and far between; now you can’t swing a dead cat without hitting one and all have their own method of making a blade. All this talk about cats is making me hungry; I like cats they taste just like chicken.
Just a bit more and we will get to the rat killing (Notice that I did not mention cats this time, but rat does rhyme with cat.) but first we must dispel some of the myths and misinformation surrounding this subject. There are no magical or mysterious processes that produce an exceptional blade. Each type of steel reacts to a certain set of conditions in a certain way and it reacts that way every time. You must learn how to handle and treat the type of steel you select to use.
Failures: You are going to have them they are learning experiences get used to it. Keep accurate records of what you did so that you don’t make the same mistake twice. Remember that experience is that portion of our knowledge that lets us recognize a mistake when we make it again.
Steel Types: In order to make a blade, you must know what steel you are working with. Any steel with over 60 points of Carbon is fully hardenable and therefore should make an acceptable blade. There are some alloys with less than 60 points of Carbon that are also suitable blade material. The SAE had developed a numbering system to define the types of steel. The first two numbers are the steel alloy and the following numbers are the points of Carbon. A point of Carbon is .01% or one hundredth of one percent. So 52100 (ball bearing steel) is 52 (a high Chromium content alloy) and 100 (100 points of Carbon or 1% Carbon). The chart below defines some of the most common steel alloys: For starting out in making a blade I would recommend you stay away from 52100 until you have more experience. 52100 makes a great blade, but it is very difficult to work with and a string of failures at the start is not a great confidence builder. I would recommend that you start with 5160 which is spring steel or some of the plain Carbon Steels in the 1075 to 1095 range.
Acquiring the Steel: There are two schools of thought on how to get the steel you use. They are not Petty Theft and Pay for It! They are using Virgin Steel purchased from a reputable supplier, or using Junk Yard Steel. The advantages of working with Virgin Steel is that you always know what you are working with but with Junk Yard Steel, you are never quite sure. The advantages of working with Junk Yard Steel are that it is readily available and if you screw up a piece you are out 50 cents where if you screw up a piece of Virgin O-1 you are out 20 bucks. I generally use coil or leaf springs. Truck Coil Springs are either 5160 or 1095 and Truck Leaf Springs are 1085. Auto Coil Springs are 4360 or 1095 and Auto Leaf Springs are either 5160 or 1085. There are many that swear by old files for knives. Files are 1095, W-1 or W-2. All are excellent knife material but the W series of tool steels are a bit harder to work.
Preparing the Steel: Let’s say that you have acquired a piece of leaf spring from a car, first clean it up with a wire brush to get most of the gunk and rust off of it. Inspect it for obvious cracks or fatigued areas. Then cut it into manageable chunks with a chop saw or hot cut. Use a gas axe if you must. After the material is in manageable pieces, you should anneal the steel to make it as workable as possible. Heat the piece or pieces of steel to a bright red and drop them into a bucket of ashes, lime or vermiculite. Let them cool over night. Now you are almost ready to start your blade, but first weld a piece of 3/8 inch square bar about 18 to 24 inches long on one end of the piece of spring. This will give you a nice handle to hang on to while you forge the blade and you can cut it off when you are done. Much easier than trying to handle the thing with tongs. Last, but certainly not least, before you start forging the blade, draw the shape of the knife you intend to make on something preferably a steel sheet with a piece of chalk. This will give you a ready reference to determine your progress as you forge the blade.
Forging the Blade: Decide if you are going to make a full tang knife or a hidden tang knife. A full tang knife is one where the handle scales are just riveted to the tang and the tang and the handle are the same shape. The edges of the tang are visible. The hidden tang is one where the tang goes through the center of the handle and the tang is not visible. I won’t go into great detail here, if you cannot take a piece of steel and hammer it into any shape you desire, what are you doing here? Revert to stock removal that is where you take a big piece of steel then grind or file away everything that don’t look like a knife. How close to the actual finished design you forge your blade is up to you. Check this website http://www.principalmetals.com/ > property data > for proper temperatures for working the metal. This site also had great information on heat treating and tempering various steel types.
Normalizing the Blade: Once you have forged the blade to the desired shape make sure it is as straight as possible then reheat to a bright red and let the blade cool. I sometimes just turn off the gas forge and leave the blade in it to cool down as the forge cools, other times I take the blade out and let it air cool. Do not lay the blade on a cold surface such as the face of the anvil as it can act as a heat sink and actually partially quench the blade.
Rough Grinding the Blade: If you intend on making a primitive blade, stop here, and proceed to sharpening. I use a 2” X 72” belt sander with a 36 grit belt to rough grind the blade. I take out all the forge marks and cut the blade to its finished shape but I leave enough metal that I can take out a slight warp if one occurs in the heat treating process.
Heat Treating and Tempering: Note that heat treating hardens the blade, tempering softens the blade and removes brittleness to the desired level. They are not one and the same Once the blade is rough ground, heat the blade to just above the temperature that it goes non magnetic. On some steels it is desirable to hold at this temperature for a few minutes. Check http://www.principalmetals.com/ for proper time and temperatures. I like to hold the piece at temperature for about 5 minutes. I generally heat the piece to bright red, remove it from the forge and stamp my touchmark into it, then return it to the forge and bring it back up to heat. Once the piece has reached the proper temperature, quench it in oil. I quench in a 6 gallon bucket containing about 5 gallons of oil from a deep fat fryer I got from a restaurant. I go straight in to the oil point first up to the tang and then make figure 8s till the piece is completely cool and the tang has gone back to a black heat then I quench the tang. This gives me a tang that is much softer than the blade. I remove the blade from the oil, scrub with soap and water to remove all the oil, sand lightly with some coarse sandpaper to remove the scale and then temper in the oven at 375o F for about 3 hours. The tempering process is on Logarithmic scale of decreasing value the first hour is more important than the second hour which is more important that the third etc. until a point is reached that further time spent is not worth the gain that is obtained. The tempering process allows for the transformation of the carbon structure from Martensite to Austenite. It should be noted that there are more recipes for tempering a blade than there are for cooking a cat. (So many cats so few recipes) (Notice how I craftily wove cats back into this article). Many of the tempering processes used are well founded in fact others are pure fiction and superstition. Some swear by triple quenching, that is heating and quenching the metal 3 times, others swear by triple tempering that is heating the metal to the tempering temperature 3 times and allowing it to cool. This may be necessary with some of the deep hardening steels like 52100 and M-2, but not really necessary here. There are also those that swear by selective heat treating and tempering, that is quenching only the cutting edge and allowing the spine of the blade to cool like I did to the tang when tempering the blade. This produces a blade that has a hard cutting edge and a soft flexible spine. Use what works for you.
Finish Grinding and Polishing: Once the blade has been tempered, check it for any warping that may have occurred in the heat treating and tempering process. You can do this by laying it on a perfectly flat surface, first one side then the other. Look to see if there is any daylight under the blade. If the blade is slightly warped, you can take the warp out with the belt sander. If there is serious warping, the blade will have to be reheated and hammered back into shape. I use a 120 grit belt to remove the grind marks from the 36 grit belt. Once the rough grind marks have been removed, you must decide how much finish you want to put on the blade. Some people stop here, I prefer a mirror finish on my blades. I start by clamping a piece of angle iron in the vise, and then use a C-clamp on the tang to secure the blade to the angle iron. This gives me a rigid flat surface to work on. I take a piece of 1” X ¼” flat bar and wrap the sand paper around it. I start with 150 grit sand paper and remove all marks made by the 120 grit belt. Then I progress to 220, 320, 400 and 600 grit making sure the all marks from the previous grit are removed. Once I have finished with the 600 grit, the blade has a fairly polished appearance. I then move to the felt wheel on the buffer. I buff the blade with black compound first, then switch to white and buff again. This gives a very high polish to the blade. I then finish by hand sanding with 2000 grit wet or dry sandpaper followed by red rouge on a cloth and finally polished with paper towel.
Other finishes that are commonly used and nice are a satin finish that is put on with a Scotchbrite Wheel on a buffer. Another beautiful finish is the jeweled finish that can be made by chucking a pencil in a drill press with the eraser down. The eraser is then dipped in valve grinding compound and pressed to the blade as the drill press turns. Move to the edge of the polished circle you have just created and repeat the process.
A word or two about belt sanders and buffers. The belt or felt wheel will grab and throw a blade with more force than you can imagine.
Belt sanders eat skin and flesh faster than steel
The edge of the belt will cut you like a knife.
Do not stand directly in front of the buffing wheel.
Do not let the edge of the blade that is away from you contact the wheel, this will immediately cause the blade to catch and be thrown.
Do not sharpen the knife before you buff it. If the blade catches a sharp knife, the knife and your fingers will hit the floor at the same time.
Always wear safety glasses AND a face shield when grinding or buffing. Safety glasses alone will not protect your eyes. They are meant to protect from straight on impact. Small particles can come in from the side or under them. Trust me, having a piece of steel fished out of your eyeball is no fun.
Putting on the Handle: If you haven’t already, decide what you want to use for handle material. The selection of materials range from local Hardwoods, to exotic Hardwoods, to bone, various horns, man made materials like Micarta, Corain, and other plastic and resin products. Keep in mind that the term hardwood has absolutely nothing to do with the hardness of the wood. Hardwood comes from trees that shed their leaves, softwood comes from trees that have needles and don’t shed them. Balsa wood (model airplane stuff) is a hardwood. Douglas Fir (harder than Chinese Arithmetic) is a soft wood. As a matter of information, I cannot recommend any portion of a cat that is suitable for handle material. You should also decide what material you intend to use for hardware that is the hand guard and the butt cap. Here the choice of materials range from the exotic, Mokume Gane, to the mundane, Mild Steel. Some say that the only difference between a $50 knife and a $500 knife is finish and hardware. Once again you have the choice of purchasing new material, or finding your own. Some of my personal favorites are
Full Tang Handle: If your choice is a full tang handle, you must first cut and fit the hand guard or bolsters and rivet in place. Many people like to put some solder or silver solder under bolsters or solder the guard in place before riveting. This forms a tight seal to the blade and keeps moisture out from under the hardware. A butt cap or bolsters, if you are planning to use one should also be secured to the end of the tang. The scales, slabs of handle material, are then just fitted and glued in place. Some people drill the tang for rivets before putting on the scales, I prefer to glue everything in place and then drill the whole works at one time. If you do it this way, put a piece of wood under the knife handle to prevent the drill bit from tearing out a chunk when it comes through. Your choice of rivets range from store bought to home made. Some people use 1/8 inch brass welding rod for pins and peen over the ends. There is also a wide variety of store bought mosaic pins that are available or you can once again make your own. Use a rasp, belt sander, file and sandpaper to shape the handle to your taste.
Hidden Tang Handle: First you must cut and fit the hand guard if you have not purchases a pre made one. I use 3/8” thick brass stock to make my own. I cut the piece for the hand guard, mark the size of the tang on it then drill it with the appropriate sized drill bit. I use a cold chisel to cut out the material between the holes then do the final fitting with a file. Once this is fitted, I put heat stop paste on the blade just below the guard and silver solder the guard in place. I don’t know what it is called, but I find the silver solder with the blue flux works the best for me. It melts at a low temperature and is very strong. I then cut off the end of the tang to a suitable length and braise on a quarter inch coarse thread bold that has the head cut off. You can use a smaller size machine screw if you desire. I take the piece of brass stock I will use for the butt cap and drill a half inch hole approximately half way through it. I set a ¼ inch nut in the hole and silver solder it in place. Putting a bolt in the nut and taking it out as soon as the solder is set will keep the threads free of solder. Have a couple pairs of pliers handy for this. Now grind off the nut flush with the brass. Now all you have to do is put a groove in each handle scale, then place them over the tang apply 10 minute epoxy to the edges and clamp them together. Now pull them off the tang still clamped together before the glue sets. Decide what spacer and accent material you want to use and cut them the same size as the handle and then cut the hole in the center for the tang. Some common spacer materials are pieces of various colored plastic, thin pieces of brass, copper, or aluminum, thin pieces of wood of a contrasting color, or leather washers. You are only limited by your imagination. Once the glue on the scales has dried, dry assemble the handle and screw on the butt cap Adjust the butt cap for the tightest possible fit by adding spacers or by using the belt sander to grind off a small portion of the bolt on the end of the tang. Once everything fits tightly, disassemble the handle, mix a good amount of 5 minute epoxy then apply glue to each side of each piece as you assemble it. Get as much glue inside the handle as you can. Once everything is in place, apply glue to the butt cap and screw it securely into place. Once the glue is dry, use a belt sander, rasp, file, sandpaper or more likely a combination of several of the preceding to shape the handle to you taste and fit. I shape the butt cap and hand guard at the same time I shape the handle using the belt sander. Any imperfections in the handle can be repaired by taking some of the sandings, mixing them with super glue and packing them into the crack or imperfection. The super glue dries almost immediately and then it can be sanded smooth leaving an undetectable repair.
Finishes: Once the handle is shaped and sanded smooth, a finish of your choice can be applied. Materials like Corain and Micarta require no finish as do stabilized woods. Otherwise you must put some sort of finish on the handle. Penetrating oil finishes like Tung oil are the best. They penetrate deep into the wood and bond with the wood to seal it. Apply several coats, sanding between coats. Lightly sand the finished coat and buff with a felt wheel and red rouge. With stabilized woods and some of the resin materials like Corain and Micarta, just sand out to 600 grit then buff with a felt wheel with red rouge for a high polish finish.
Sharpening: The last thing I do is sharpen the knife. Why, because I like my fingers that why all 9 and ¾ of them. I put tape on the blade to protect all but the area I will be sharpening. I use a 120 grit belt on the belt sander to do the rough sharpening. Then I clamp the knife to a board or piece of angle iron in the vise and carefully sand out any scratches made by the belt sander. By working on the slack part of the belt on the sander, scratches are kept to a minimum. Once the scratches have been removed, finish sharpening on a wet or oil stone, then polish the edge of the blade with 2000 grit sandpaper.
Afterword: You cannot make things Idiot Proof. If you follow these instructions and end up hurting yourself, take responsibility for your own actions and don’t blame me. You could sue me, but getting any money out of me would be like trying to poke butter up a wildcat’s backside with an ice pick. You can do it but you are apt to get scratched up a bit. (geez, I slipped a cat in there and you didn’t even notice did ya?) For most of you who know me or know of me, did you really expect me to sit down and write 7 serious pages of material? If you did, I suspect you may have been drying your hair in the microwave again. Some will go through this article with a fine toothed comb to see how many times I mentioned cats. I don’t know and you really need to get a life. For a relative few who actually try this, there is nothing more rewarding than making something beautiful with you own two hands. A well made knife is a thing of great beauty. If you ever make one that you are completely satisfied with, you are giving up too soon. Like I said in the beginning this is not meant to be a definitive text on knifemaking. It is merely one mans way. Others have their ways and they are also correct. Learn from many, then take what you have learned and develop your own style. Remember that it is not the destination that counts, it is the journey to get there. Enjoy the ride.