if there is anything incorrect in this instructable, please let me know.
Also, these pictures are from google images to illustrate my points.
Step 1: The Law
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
Step 3: Parts of a Knife
Step 4: Type of Knife
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
Step 6: Tang
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
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
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
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
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
Step 13: Knife Steel Type
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