Step 1: Materials.
You will need:
- 1 inch diameter pipe.
- 3/4 inch diameter wooden dowel.
- 3/4 inch diameter washer.
- 3/4 inch diameter spring (ID # C-756).
- Screws, 1/4 inch diameter.
- Fishing line.
- Smaller dowel.
- Small metal dowel.
- Suitable safety pin wire.
Step 2: Cut to Length.
Step 3: Build the Mechanism.
First you need to drill a 1/8 inch guide hole through the center of both your plugs. Use a clamp to hold the plug in place. Now for the tricky part. Place your 3/4 inch washer over the base of your spring and line it up with the plug, try to make it as flush as possible. Tightly screw the washer and spring in place, you can do this through the side of the spring. Repeat this for both ends of your spring.
Step 4: Safety Pin Hole and Securing the Mechanism.
. Reinsert the mechanism, making sure it slides smoothly. Make sure that the base plug is flush with the bottom of the pipe. Drill a guide hole through both sides of the pipe and plug, roughly 3/16 inch from the bottom. Secure the mechanism with a screw on both sides of the pipe.
Step 5: Finishing Touches.
Epoxy a 71/2 inch metal dowel slightly below the pin hole. This serves as a stake, allowing the trip mine to be secured to the ground.
Use another small wooden dowel for the tripwire's stake. Whittle one end to a point and split the other end. The tripwire will be fastened to the split. Tie the other end of the tripwire to the safety pin.
You can spray paint the trip mine to blend in with it's surroundings. I did a base coat of black and misted light green over it. The prototype is a base paint of green with a mist of black. I used some ghillie left over from my ghillie suit to further camouflage it. You can also attach local flora with a black rubber band.
Step 6: Operation.
View the video below to see the trip mine in action. YouTube's quality is horrible, I'm using Metacafe instead.
This is the detonation of the trip mine at 1200 frames per second:
Step 7: Measurements.
You can pour a good amount of BBs into this, I'd say about twenty or thirty. These average twenty-eight feet. Combine BB's and powder for the best effect.