Some were interested in seeing this post so I'm reposting it.
This is the same post I made a few years ago but got lost in the last board clean up. Luckily I had copy & pasted it to a hiking board that I'm a member on and I came across it today....
Figure 4 Deadfall Trap
I will start off by saying that this pictorial is just to show how to assemble a figure 4 deadfall trap and should ONLY be used if you ever find yourself in a true life or death survival situation.
There are three parts to making a figure four trap and I will refer to them as:
1) The upright (vertical stick)
2) The support (angled stick that supports the rock or log)
3) The trigger (horizontal stick)
The stick diameters and lengths will vary depending on what your trying to trap.
I start by carving a "chisel point" in the top of the upright.(see the third picture down to see the "chisel point".)
Next I put a notch in the top of the support stick. I do this a couple inches down from the top of the stick.
I use the saw on my Swiss Army Knife (SAK) and saw straight in.
Then I use a blade and carve in toward the saw cut on an angle down to the bottom of the saw cut.
This is what they look like and how they fit together.
Next I make another chisel point on the bottom of the support stick. Make sure that the chisel point and the notch on the support stick are lined up correctly.
Then make a notch on the back and the top side of the trigger stick.
These are the same as in the pic's above.
Next I put everthing together and hold it in place. Then I make a mental mark on the upright where the trigger stick rides. You can use your knife to mark this spot but its hard to hold everything together and mark it.
At the mental mark you carve a flat spot on the side you want the trigger stick to be on (its not important what side its on). Then you carve a flat spot on the front of the upright. The two flat spots should give you a clean square edge.
Now you need a notch on the trigger stick to "lock" onto the square on the upright.
I hold it all together again and make another mental note on the trigger stick where the notch should be. The notch is the same as the notches pictured above but the part you carve in needs to be longer (start back farther away from the saw cut) and flat.
This is what the square and notch should look like.
Here they are put together.
Here is a picture of the "front" and "back" of everthing put together.
I put the upright in place
next the support
next I put my stone/log
then while supporting the whole thing I put the trigger stick in place and allow enough pressure from the stone/log to "set the trigger".
then slowly let go and back away.
The weight from the log/stone you use holds pressure on the whole thing untill something comes along and trips the trigger.
A few things to know when setting.
*Keep the area clean of "lumps", you want your stone/log to be able to come straight down without any obstructions.
*When using on soft ground place a small flat
stone under the upright to keep it from sinking into the ground.
This was just a simple one I made for practice.
There is much more that can go along with this. Like placement, making a hair trigger, baiting, ect.
If there is enough interest I can go into it further.
Thanks for looking and feel free to ask any questions.