Introduction: Profiling a Knife Shape, From Concept to Execution.
As a knifemaker, whether you're a first-timer or a veteran, one of the most basic skills you need to develop is blade profiling. Essentially, that amounts to developing the basic blade shape that will eventually become your finished knife.
There are two general approaches to making a knife. On the one hand, you can forge a blade from a piece of steel, bending the metal to your will such that it reflects your ability and taste. If you've seen the last Rambo movie, you have an idea of what this entails.
On the other hand, you can do what's commonly known as stock removal, wherein you begin with a piece of raw bar stock and basically take away what doesn't look like a knife.
While both methods are quite effective at producing superior knives - in fact, many knifemakers employ both approaches at some point in the fabrication process - for the purposes of this instructable, we will be focusing on the stock removal method.
When you finish the profiling process, it should look something like the first picture.
As we go through this tutorial, you will see some pretty cool tools. If you're lucky enough to live near a Techshop, take advantage of it. I made it at Techshop. They have awesome tools, lots of light, and plenty of space.
Step 1: What You Need:
Just as there are different ways to profile a blade, there are different tools that you can use to perform the task. Some are convenient, others are absolutely necessary. While one absolutely can perform the entire knifemaking process using only hand tools, I prefer to use power tools. But in case you only have access to the basic ones, I chose to minimize the tools we use here.
For this task, you will need:
Layout table (or kitchen table!)
Pen/Paper or CAD program (I used Inkscape, a free downloadable program that can do practically everything Adobe or Corel can do for our purposes here.
Pedestal grinder/bench grinder
Water bucket (for dunking hot steel)
Metal for the knife
Step 2: A Note on Safety
Before we go further, let me stress the importance of being safe. Power tools are dangerous. Be careful. While the ear protection is optional, eye protection absolutely is not. When hogging off metal using a pedestal grinder, sander, or angle grinder, each of these tools produces substantial amounts of metal particles. Believe me when I tell you they hurt when you get one in your eye.
Don't believe me? Check out all the grits of metal on the floor beneath the pedestal grinder. If I remember correctly, I was about halfway through the profiling process at this point. If any of those grits gets into your eye, you will need a doctor to pull it out. So please, be careful
Step 3: Choosing the Knife Steel
Now, this is one of those questions where, if you ask 50 knifemakers what their favorite steel to use is, you'll get 100 answers. The reason for this is simple. Each steel has its own benefits and deficiencies. Likewise, each knife type demands different things of the steel from which they're made.
I prefer to use 5160, which is in my opinion the very best knife steel for knives that will be used for chopping, heavy cutting, camping/hunting, zombie killing, and, believe it or not, swordmaking. There are a number of reasons for that.
First, 5160 is a remarkably stable, tough, and deep-hardening steel. This is due to the fact that 5160 contains substantial amounts of chromium, which allows for deep hardening, and "only" 60 points (0.60%) carbon, meaning that while it can be hardened through proper heat treatment, it doesn't have so much carbon that it becomes brittle. Brittleness can be a problem with higher-carbon steels. I should also add that 5160 is relatively forgiving when it comes to the heat treatment process. You can make a lot of mistakes, and still come out with a functional blade. The same cannot be said for many other knife steels.
All of the camp knives, combat knives, even chef's knives I make, I use 5160. But you choose your own. And feel free to experiment. O1 tool steel is a particularly good choice for hard use, as it has more carbon (allowing it to harden more) and similar amounts of chromium as 5160. It also is relatively forgiving when it comes to heat treatment. Still, it is not as forgiving as 5160.
The picture here is what your typical hot-rolled bar stock looks like. Note the matte finish. Yes, that has to eventually be ground off somehow, but that's a separate instructable.
Step 4: Developing a Blade Shape
When designing your blade shape, it's important to keep in mind your desired use. No knife will do everything. And typically, a knife designed to perform many tasks will not perform any of those tasks particularly well. Usually, such a blade will do one or two things decently, and a number of other things passably, and other tasks terribly.
Take for example a throwing knife. It's really only good for, well, throwing. You could conceivably stab with it, or open a letter pretty well. But you probably couldn't cut your steak with it very well, and you definitely couldn't baton wood to make a campfire.
On the other hand, consider a camp knife. It is probably pretty good at batoning wood. It's probably pretty good at cleaning game and cutting meat. But throwing it? You'd be better off throwing a stick instead.
I have included a couple of designs here to give you an idea of how to do this.
Once you have decided what type of knife you want to make, it's a simple matter of drawing the desired profile on paper. You then cut out the paper and use the blade shaped paper as a template to transfer onto your bar stock. See below. This is where the pen, paper, Exacto knife, and Sharpie pen come in handy. Also, make sure (using the tape measure) that the knife shape you desire will fit onto your barstock.
Certainly, there are other ways to do this. Some knifemakers, particularly those who make many knives of the same shape make a blank that they then employ to scribe out the shape onto their barstock. But for our purposes, since we're talking about your first knife, or perhaps just a single knife, this process is cheaper and easier.
Once you have cut out the blade shape, simply place the paper form onto your barstock, and carefully color the metal, making sure you leave a sharp (pun intended) line that will be visible to you while grinding away on this hunk of steel.
I included pictures from a couple of my knife projects to give you an idea of what it will look like.
Step 5: Grinding the Knife Shape.
Assuming you successfully transferred the overall shape of your desired blade to your barstock, you should have a nice, clear template outline on your steel. Now comes the fun part.
Put on your goggles and your ear protection first. Then, go over to the pedestal grinder (or bench grinder, if that's what you have) and adjust the plastic shield so that it rests between your face and the work. Once you turn it on, SLOWLY proceed to hog off metal from the bar. Go slowly because the steel heats up quickly (necessitating the dunking of it into water) and because the pedestal grinder is a dangerous tool if you are unfamiliar with its functions and uses. In case you're wondering, typically (though not always) the left wheel is the lower grit (meaning it will more aggressively remove material). It will also heat up your work faster, so be careful.
I prefer to never wear gloves while operating machinery like this, as it's really easy for your glove to get caught (in this case, by the rotating wheel) and literally rip a finger (or worse!) off of you. So again, BE CAREFUL!
Make sure you press ONLY into the flat edge of the wheel. Otherwise, the centrifugal force of a damaged wheel can literally blow it apart, sending shards of abrasive stone everywhere... into you. So BE CAREFUL!
Anytime the work heats up, dunk it into your bucket of water. Continue this process until you've gotten as far as you can with the pedestal grinder.
Step 6: Optional Step: Using the Angle Grinder
Sometimes, you will get to a point where using the pedestal grinder to remove material is just too difficult, or even impossible (depending on your blade profile). This happened for the project knife I posted for this Instructable.
Notice in the picture that there are clearly large chunks of metal that have not been removed yet. Often, you'll find that if you need to do this, it may be easier to employ an angle grinder. Just be careful, because it can be a bit difficult to control if you don't have a lot of experience using one.
Chuck the work piece into your vice in such a way that you have good access to the parts you need to remove.
Also, make sure that you have a CUTTING wheel on your angle grinder. Each wheel type gives you different capabilities. A cutting disc is great for, well, cutting! And a grinding disc is great for... you guessed it... grinding. Just be aware of what you're using, and you should be fine.
Step 7: Cleaning Up Your Burrs
So now that you have managed to get most of the material off, and you have what looks to be a hunk of steel that looks like a knife, it's time to clean up the piece, and deburr it. When you remove steel using either a pedestal grinder or angle grinder, there's a tendency for the steel to leave sharp edges that can cut you really badly.
CAREFULLY handle the blade. It's way more dangerous at this point than you know. You have a couple of options here, and you can employ both. For this project, I did.
Swap out the cutting disc for the deburring or grinding disc on your angle grinder. Carefully clean up the sharp edges, being aware that you don't want to remove any more material than necessary, since it can affect your overal blade profile. The angle grinder is great for small areas that you can't reach with the disc grinder.
Next, walk over to the disc grinder and refine your shape. The disc grinder will give you a very clean, flat finish, perfect for setting yourself up for finishing the knife. Go slowly. Taking a little extra time here and there can and often does mean the difference between a piece of crap and a really nice, functional knife.
Step 8: The End! for Now...
Well, there you have it. You've successfully profiled a knife! It should feel good in your hands, and have the general shape you originally planned. keep in mind that as you grind in the bevels for the blade edge (the next instructable!) the blade end will get lighter. So don't worry if it feels a bit tip-end heavy. That will sort itself out.
I will be posting the next part of the process to make a knife, very soon. Stay tuned!