The figure 4 trap trigger is the classic three-stick deadfall release: an upright post, a diagonal, and a horizontal bait stick that lock together in the shape of a numeral 4. Cut correctly, it holds a heavy rock steady and drops it the instant an animal moves the bait arm. Cut sloppily, it either collapses on its own or never fires.
The three sticks
- Upright (post): roughly pencil-thick, 8–10 in, flat bottom so it stands on hard ground.
- Diagonal: same thickness, slightly longer than the upright, carries the weight.
- Bait stick: the longest of the three, runs horizontally under the deadfall.
The three cuts
- Chisel the top of the upright to a flat wedge (a screwdriver tip, not a knife point).
- Notch the diagonal near its top so it seats on that chisel and cannot slip sideways. Cut a matching square notch partway down the diagonal for the bait stick.
- Notch the bait stick so it locks into the diagonal's notch, and chisel its inner end flat so it presses against a shallow catch on the upright.
The whole system relies on friction and geometry. If the diagonal's notch is rounded, the trap creeps and fires early. If it is too deep, it binds and never releases.
Setting it
Stand the upright, seat the diagonal, then walk the bait stick in last while supporting the deadfall with your free hand — never with your fingers under the rock. Test the release with a stick before you leave. The rock should fall clean, flat, and fully cover the bait area.
Why it fails
- Green, springy wood flexes and unlocks the notches.
- The deadfall is too light — a flat rock should be several times the weight of the target animal.
- The bait stick sits too high, so the animal feeds without loading the trigger.
- Uneven ground lets the deadfall land on a rim instead of the target.
Legality
Deadfalls are a survival and practice skill. In almost every jurisdiction they are not legal for recreational trapping. Practice on your own land with bait and no target animal, or check your state and provincial regulations first.
Related skills
Pair this with cordage, notch-cutting practice, and knife control — see our survival skills library and the Top 10 knife and axe lists.
FAQ
What is a figure 4 deadfall trigger? A three-stick trigger — upright, diagonal, and bait stick — notched so they interlock and hold a deadfall weight until the bait stick is disturbed.
What wood works best? Straight, dry, hardwood sticks. Green wood flexes and causes misfires.
Is a figure 4 deadfall legal? Generally not for recreational trapping. Treat it as a survival and practice skill, and check local regulations.