How to make a knife – Part 2 by Anthony Bear
Before you get stuck into this blog post which is full of some really great information be sure to check out the first part of Anthony’s Blog which looks at how to get started in knife making!
Making the knife…
Ok then now it’s time to have some fun and get our hands dirty and make this blade come to life.
We will work on the bushcraft design mentioned in the last blog, which will be a rat tail design and using mainly hand tools.
To start off lets look at the very basic tools you will need to make this knife. As I mentioned in the first blog I made my first blade using only hand tools and with 1095 high carbon steel but for this project we will use the angle grinder and O1 tool steel, as its easier to get your hands on in the UK.
As you can see the very basic tools consist of hack saw flat, half round, bastard and mill files ( these are the only tools I used for the first blade ) angle grinder with cutting and flap sanding discs. It is also a good idea to use something like a sharpie to mark the steel as welders chalk doesn’t give you a clear enough line and pencil is near invisible.
I personally use a liquid chalk marker as it easily writes over the oil that comes on the steel and it doesn’t fade when the steel heats up when cutting with the angle grinder.
Transferring the design to the steel.
All of my designs go in to my A3 sketch pad as a lot of my designs have little variations and so I can put them full size on the same page for good referencing. Now all that’s needed is to simply trace the design on to some A4 paper, cut it out and trace round it on the steel. If you do your design on the computer then pretty obvious just print it, cut it out then trace onto steel.
If you are happy to go free hand with the design then that’s perfectly fine as its your creation so whatever works for you. Remember these are the steps I use but I am in no way saying that they are the best, they just get me good results.
Now if you are no stranger to working with metal then you will have no problems going to town with the angle grinder. If you are not familiar with the angle grinder then please, please, please be safe wear protective gear gloves, goggles, mask and have a fire extinguisher at hand just in case. Remember you wont get the exact shape at this point even with a hack saw, you simply need to get the rough outline as you fine tune everything later with the files.
There are a few things to remember when doing the initial cut out. One is don’t remove your outline as this is your reference when filing. Two is, when doing a rat tail blade, make sure that the tail is longer than it will need to be, I will explain why a little later. Three is, try not to have any right angle cuts where the tail meets the blade, if they can be rounded off with the files later that’s perfectly fine but it is a very bad idea to leave right angles at this point which will later be explained.
Note that the rough cut right angle edges have been filed round. This is important when we get to heat treating the blade as its at these right angle points, during the quench, that stress fractures occur which means a blade that will last all of about 5 seconds being put through its paces.
After these areas have been sorted its time to get to work filing the rest of the blade to near final shape. I do recommend going stead at this point as filing can be a little laborious and it is easy to fall in to the trap of going crazy to get finished quicker and end up taking it too far.
Of course, now it’s time to think about the cutting edge or grind. There are a few different types of grind you have the option of doing, such as convex, flat, hollow and chisel. As you may see with many mass production blades, they have a double grind. That’s not to say that they aren’t good blades. It is simply a matter of production. I personally like the convex grind and here’s why;
It holds an edge very well especially when put under stress when performing tasks such as chopping wood etc. This means it is less likely to chip therefore reducing the need to spend extra time resharpening. As with all blades, maintenance is very important but if you constantly need to do a total resharpen then to me it isn’t a good blade.
Before you go ahead and get to the filing or grinding you need to mark out the centre of the blade. This can be done a few ways, you can simply get a nail or a screw and scribe the edge or you can at the very least use a pencil. I use a centre scribe simply because I came across one for sale and also because of the number of blades I produce.
Here’s the scribe
If you are going down the route of filing the grind, you will have a better chance of controlling how much material is being removed but it is time consuming. Using the angle grinder is much quicker but, it is easy to remove too much material and mess up the blade so you must remember to really go steady.
It is important when doing the initial grind that you don’t take the cutting edge too far. By that I mean don’t try and make the blade sharp at this point. You need to leave material to be removed later on after the quench.
Another good thing about the convex grind is, it is a grind that doesn’t need to be perfect as you’re doing the initial filing or grinding. The smoothing out of the blades surface can be easily done later.
Threading the rat tail
This step is simply the way I prefer to secure the pommel to the handle material. I have, in the past, tapped all the way through the pommel but as I mainly use brass I didn’t want to see the rat tail through the brass after being screwed down. So it is simply a case of only tapping 2/3 into the pommel.
First round of polishing up the blade
Ok so as you will have noticed, after doing the first grind, that the blade surface is far from smooth and so a little tip before heat treating is to go to work with the 120 grit sandpaper to try and get out some of those scratches. You don’t need to bring the surface to a mirror finish, this step is simply to help you out after the heat treatment and tempering because remember, you are working with annealed steel which means that its soft and workable. After the heat treatment and tempering the steel is much harder and less easy to work.
There are quite a few ways knife makers heat their blades for heat treatment but for now, with this size blade, I will tell you the simplest way to heat the blade. Turbo torch! Rather than trying to set up a forge pit or anything like that simply purchase a turbo torch with MAP gas.
Now here is where you need to keep your cool because as the blade gets to normalising temperature you need to be ready to go from your heat source to your quench bucket.
First of all I will give a quick explanation of normalising. Normalising is basically heating the steel to a point where it no longer has a magnetic signature. So the easiest way to check this is as the blade gets to an equal orange/red glow use a magnet to see if it attracts, if it does keep the heat on making sure to get equal distribution of the heat across the blade. Once the magnet does not stick then its a super quick transition to your quench bucket. Now different people use different quenching mediums. Right now I use cooking oil but, now there may be people wanting to scream at this, when I did my first blade I used nothing more than water and earth. I researched the old school blacksmithing methods and found that simply using earth and water worked absolutely fine and it did for me with my first blade, I can still shave hair with that blade even after chopping wood! Just remember that you must raise the temperature of the earth and water mix to avoid the blade cracking. This can be done by heating a scrap piece of steel to red hot and dunking it in the quench solution just before you start heating the blade. The ratio of water to earth was roughly about 4 litres of water to 4 handfuls of earth.
Hold the blade in the quench bucket for about 60 seconds then simply allow to cool to ambient temperature on a piece of timber.
PLEASE NOTE: SO THAT NOBODY GETS INJURED, REMEMBER NOT TO HOLD THE BLADE WITH YOUR HANDS WHILE HEATING! THATS WHAT THE GRIPS ARE FOR. ALSO PLEASE USE THE CORRECT SAFETY GEAR.
So the blade has been heat treated and is now cool enough to handle. It is now time to quickly give it a rub with the sandpaper to remove the scale that forms during the heat treat, you don’t need to go crazy just remove the bulk.
Pre heat your oven to around the 350-400 f mark once you have it heated up pop the blade in take a note of the time and now you have 2 hours to clean up and have a cup of tea. Try to avoid opening the oven during this time as you really want the temperature to be maintained.
After 2 hours has passed remove the blade from the oven and allow to cool to room temperature. You should notice that the steel has gone to a straw colour which is exactly what we need to see. If its only slightly tinted with a straw colour then it needs another 2 hour round in the oven.
I did another blade just so that you can see the colour you’re looking for.
So that’s it for this installment next time we will cover the steps to adding the handle and sharpening the blade. Hope you enjoyed it and remember this is just how I do things. If you get a taste for knife making you may find new better methods that work for you.