In one episode of "Survivorman" Les set up a Figure-4 trap but forgot to attach the bait (cashew nuts) to the trigger. He spread the nuts around underneath the trigger stick but failed to catch anything. Also, just getting everything balanced seemed to take a lot of work. The deadfall kept collapsing.

Two things occurred to me. First, me using a needle, pin or fishhook to more firmly attach the bait to the trigger would help. If the creature needs to tug on the bait the trap will definately be sprung.

Second, prehaps using a Y-shaped support stick to hold up the deadfall might make it more stable and easier to set.

-Blast

Never tried the needle idea, but a y-shaped support stick does work better than one stick supporting a giant wobbling rock.

In a different episode, or maybe another scene, he chewed an energy bar chunk into the end of the trigger stick. I thought that was a clever idea too.

Blast,

My oldest son tried to make a dead-fall, in a survival class, with a figure-4 trigger. His biggest problem was the log would roll off the trigger. He had to stabilize the log so it could not pivot to the side and off the trigger.

I watched Les in the episode you are talking about. I think Ron Hood does a great job showing how to carve a figure-4 trigger in his video.

Figure four traps are not too hard to balance once you get the hang of setting them, and learn to carve the sticks well enough so that they'll not only hold while setting the trap, but also fall reliably without catching.

On a side note, if I remember correctly, Les put the main support stick under the rock, and I was taught that it shouldn't be directly underneath the weight you're using to crush the prey. Not only will this make it less likely to hurt your hand if the weight falls, but also the support won't get caught under the weight if the trap fails for one reason or another. That's not to say that how Les set it was wrong or wouldn't work, but that there was a reason I was taught differently.

Of course I should mention that I had trouble setting a Figure Four before, and the diagonal stick flew up in the air and smacked me in the face! LOL

It must be noted that I believe I remember Les setting deadfalls in two different shows, and I may not be thinking about the same episode as you. One was in the Desert, and another in the Mountains unless I'm confused.

Regarding triggers and bait, I saw a Piaute Deadfall (similar to the Figure Four) set with a piece of straw (grass) with the bait on it as the trigger. It took almost no pressure at all to set off the trap so the bait only needed to be secure enough to stay where it was. Pretty much, if the piece of straw was bent even a little, in any direction, the straws integrity would be lost and the trap would be sprung.

I haven't tried it (yet), but here is a slightly different way of making a deadfall. It may, or may not, be easier than the carving methor...

I've found that when using a large rock/stone to make the deadfall, there's not much of a problem with the weight rolling off the support, because there's usually enough of an edge on the end that's against the ground that it can't move, it works more like it's on a hinge. With a log however, as was mentioned, you usually need to do something like put a couple rocks on either side of the end of the log that's on the ground so it can't roll.

I tell you what gets my goat is when I finally get the trap erected, and a sudden, unexpected gust of wind bumps it just enough to set it off. Definitely prefer to build my F-4 traps with a stable load with at least two points contacting the ground. One, like the log, is just too unstable.