How to Build a Live Trap for Small Animals

Reader Contribution by Instructables
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Reposted with permission from Instructables.

Built from nothing but scrap plywood and spare or recycled hardware, this innovative swing-door trap will help you catch backyard pests without harming them.

Step 1: Tools and Supplies

1/2″ plywood
1/2″ x 1/2″ strip
4 hinges
2 small washers
Bailing wire / metal hanger
Twine / String
Drill / Driver
Tape Measure
Side Cutters
Razor Blade
Drill bit

Step 2: Measure and Cut

Measure, layout and cut the following pieces of plywood:

(1) 12″ x 48″ for the base
(3) 12″ x 40″ for the walls and ceiling
(2) 10 7/8″ x 11 3/4″ for the doors
(2) 3″ x 10″ for the locks
(2) 5″ x 10″ for the triggers

and cut the 1/2″ x 1/2″ strip into:
(4) 3″L for the door jams
(2) 6″L for the lock plates

Step 3: Assemble the Doors

(Do this step twice: once for each door.)
Attach one end of a hinge to the lock. Center the lock side to side and 1 1/2″ in from the 11 3/4″ side of the door. Attach another hinge to the other 11 3/4″ side on the back or edge that will allow the door to be both open and closed without binding the hinge.

Step 4: Build the Body

Screw the walls to the ceiling (assemble upside down).

Step 5: Attach the Doors
(Do this step twice: once for each door.)

Line up the door with the lock right next to the ceiling and attach the door hinge, then, holding the door in what will be the closed position, attach the door jams.

Step 6: Attach the Base

Attach the base so that the walls are centered.

Step 7: Space and Install the Lock Plate

(Do this step twice: once for each door.)
Check that the doors swing freely without binding against the walls or base. If you used a larger hinge, you may need to shave a little more off the door.

With the door in the closed position, lift up the lock and set the lock plate next to the door. Then slowly pulling the door open, find the point at which the door swings without moving the lock plate, then pull the lock plate another 1/4″ to 3/8″ further away and screw to the base.

Step 8: Making the Sear

(*Some parts of this step require you to do them twice: once for each door.)
Drill a hole in the middle of the ceiling. Using the drill bit as an anvil, bend the wire around it to make a loop. If you’re using a coat hanger, it’s a lot stiffer, and you’ll need to use the cutters or a pair of pliers to bend.

* Loosen one of the screws on the lock hinge and tie the twine around it and re-tighten the screw. Run the twine behind the lock.

* Prop the door so that it is about 1/2″ from being all the way up. Tie the other end of the twine to the washer at the length needed to line the washer up with the hole.

Stick the sear in the hole from the inside, put the washers around it and let the weight of the doors hold the sear in place. Make sure the sear is all the way against the ceiling and that the washers are all the way down in their natural resting position. Trim the wire so that there is an extra 3/8″ over the washers.

Step 9: Making the Trigger

Set the two trigger boards on top of each other and drill a hole through both boards about a 1/4″ in from the edge, centered from side to side.

Then tie a semi-loose loop through the two holes so that the triggers can hinge freely yet still pull immediately on the twine.

Tie the other end of the twine to the loop in the sear at the length needed so that the top of the sear clears the top of the ceiling when the triggers still have another 1/8″ of travel down. This roughly equates to the trigger plates being a 1/2″ off the base at the underside of the peak.

Try to keep the triggers low as best you can. If they are too high, there will be too steep of an angle and will reduce the sensitivity of the trigger. The lower they are, the more sensitive the trap will be.

Step 10: Adjusting the Sear

Now that the weight of the triggers helps pull down the sear, we need to adjust the pull weight. While holding the sear up with your hand, set the washers into place and, using your thumb, gently push on the sear in the opposite direction of the top washer until the trap stays set. If you’re using a coat hanger, it’s a lot stiffer, and you’ll need to use the cutters or a pair of pliers to bend. You’re not trying to put a hard bend in it – just a slight arc to help overcome the weight of the triggers. Bend it too much, and the weight of your prey may not activate the trap. The less you can bend it, the more sensitive the trap will be.

Place some bait (dry cat food) on either side of the peak of the triggers right next to the twine and a little on either side of it just inside the door jams. This will entice the animal to walk further in for a better chance of attracting and trapping.

You can see more photographs of this project on my original Instructables post.

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