This is my guide for how to choose the right survival knife. This is by no means a definitive list, because it depends on your personal tastes and the situations you are likely to be in, but I hope to tell you some of the main features you should consider for a general purpose blade.
if there is anything incorrect in this instructable, please let me know.
Also, these pictures are from google images to illustrate my points.
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Step 1: The Law
In the UK, the law is fairly tight. I am not going to go too in depth about it, but my source of knowledge is here if you want to check up on it, or get some examples. In general:
You may not carry a knife with more than 3" of cutting edge, and it may not lock open. Butterfly knives, flick knives, or other assisted opening knives are also banned; if you are caught with one in public, you will end up in jail.
Knives over this length may not be carried without good reason. The exception to this is :
1. Knives carried for work
2. Knives carried for religious reasons
3. Knives carried as part of national dress
As for what a public place is:
The Prevention of Crime Act 1953 section 1(4) provides that;
'a public place includes any highway and any other premises to which the public have or are permitted to have access, whether on payment or otherwise'
This also includes your car (even if it is locked).
Step 2: Film Knives
Before I start, DO NOT be tempted by knives you see on TV and in films, such as Rambo. This is almost always the least practical knife you can have. it is much to big to be used comfortably and for delicate jobs. It is also the wrong type of tool for bigger jobs.
Step 3: Parts of a Knife
I think the picture below just about covers it. There may also be a pommel, or butt cap at the bottom of the handle, and a guard at the bottom of the blade. There might also be a lanyard hole near the end of the handle.
Step 4: Type of Knife
For day to day jobs, a small folding pocket knife will suffice, with or without a lock (depending on where you are/the common uses). For general bushcraft and survival, a fixed knife is best, as a hinge provides a weak point. I will be concentrating on fixed knives in this instructable.
For use in the jungle, i would recommend taking a large machete or axe as well, to cut your way through dense undergrowth.
Step 5: Size
For the length of the blade, I find between 4" and 6" is the ideal length, short enough to get control for finer jobs, such as carving, and large enough for heavier jobs.
Step 6: Tang
The tang is the piece of metal attached to the blade that runs inside the handle. The top tang is a a hidden partial tang or push tang. This may be useful if there is a hollow handle with a survival kit in it (a feature I would STRONGLY recommend you do not have, due to the loss of strength). The middle blade has a hidden rat's tail or stick tang. It extends the length of the handle and the handle is pressed or threaded on to it. The bottom blade has a full tang, which conforms to the shape of the handle.
Having a partial tang may not be a sign of weakness, because it all depends on craftsmanship, but I would recommend getting a knife with a full tang or rat's tail tang. This means that even if your handle breaks, you have something to wrap a cloth around or use instead.
Step 7: Knife Edge Grinds
There are many different grinds, but there are 6 main ones.
1. Hollow grind : This has a very sharp edge, and will cut through things very easily, but will not hold its edge well with use.
2. Flat grind : The blade tapers from the spine to the edge on both sides.
3. Saber grind : Saber grinds hold the edge well, but do not cut as easily as a hollow grind. it is similar to 2, but it starts further down the blade.
4. Chisel grind : As like a chisel (hence the name), only one side is ground.
5. Double bevel or compound bevel : The blade is thinner just behind the edge, which improves cutting ability. The actual edge, however, has a wider angle, so lasts longer, but does not cut as well.
6. Convex grind: This is the opposite of a hollow grind. There is a lot of material behind the edge, so it holds an edge well, and is fairly sharp. it is often used on axes, and tools for heavy use and chopping.
For a survival knife, I would recommend a saber grind or compound bevel, as these are easiest to sharpen without specialist tools, and hold their edge well.
Step 8: Blade Shape
As you can see, there are many different shapes. I am going to concentrate on the ones I would want on a general purpose knife.
1 Clip Point: The clip point blade has a fine tip, so is good for digging and picking. You can also sharpen the curved section above it, to make a lethal hunting weapon.
2. Spear point: A spear point or drop point is the standard blade shape used in penknives. it has a fair amount of material, so is very durable, and is good for cutting. It is not quite so good for delicate tip work, but is still a very useful blade shape.
I can't tell you which one is best, it all depends on what you intend to do with the knife. You would use all of the below shapes for different purposes, so think about what you are likely to be doing, and make an educated choice. Personally, I would choose a Clip point, because I do quite a lot of delicate work, but it is up to you.
If you are likely to be doing much skinning or gutting, then you might want to consider a serrated or wavy blade, which cuts through flesh like butter, but is harder to sharpen in the field.
Step 9: Blade Hardness
The hardness of the blade is measured using the Rockwell Count scale (RC scale). It is determined by teh heat treating of the blade as it is made.
High hardness (~ RC 60-65):
This is more brittle, but holds an edge very well. Impacts may cause the blade to chip, so it is suited for small knives and general cutting.
Medium hardness (~ RC 58-60):
This is suitable for a wide range of tasks, and is what you would want for a general purpose survival knife. It holds an edge fairly well.
Low hardness (~ RC 52-58):
This is the least brittle, but does not hold an edge as well. It is used for impact blades, such as meat cleavers and axes.
Step 10: Handle
Handles are made from a wide range of materials, such as plastic, bone, horn, wood, leather and rubber. Rubber provides good grip, even when wet. Bone and horn are durable, and also provide an aesthetically pleasing finish. Wood and leather have a nice finish and a good grip, but will need some treatment to stop them deteriorating. Plastic is strong and not absorbent.
The handle should comfortably fit your hand, and not leave blisters with prolonged use. This is down to personal preference.
A guard between the blade and handle will help protect your hand. A single guard is generally better than a double, because it enables a range of different grips.
Step 11: Sheath
A knife should have a sheath, to protect both it and you. A sheath should be made from a strong material, such as leather or Kydex, and have a tunnel belt loop. Also, the handle should have a strap to stop it sliding out of the sheath. Some sheaths have a small pocket for a sharpening stone, which is extra weight but could be useful. It is up to you where you where your knife, on you belt or leg or wherever, but the police may not like the idea of a concealed blade! In public places, you should take it off and put it deep into a bag, or better stilll, not carry it unless absolutely necessary.
I think I have covered everything, if you think of anything else, then tell me. You may have noticed, but there is no perfect survival knife. Nobody can predict exactly what will happen to them, so a knife has to adapt. Finally, be safe when using a knife, I have seen many injuries due to carelessness, but enjoy the outdoors.
Step 13: Knife Steel Type
There are countless different types of steels, but for a survival knife they fall into two categories - stainless and carbon. Stainless is more rust resistant, and can be more brittle, but does not hold an edge so well and is harder to sharpen. Carbon steel is tougher, easier to sharpen and holds an edge well, but may rust if not cared for.
I have no experience personally, but i found a list here of some recommended survival knife steels.
Recommended Stainless Steels
CPM 154 (this is my favorite stainless steel)
Recommended Carbon Steels
A2 (this is my favorite carbon steel)
If you want to do more research, then this link is very good.
Step 14: Image Sources