***** MAILBOX TRAUMA *****
(c) by Carl Chetta 1997
Text written by Larry Lund
The little ones come to your front door
and press your doorbell, suddenly, the mailbox adjacent to the door bell flies
open and a hand comes out to grab them. This is accompanied by a loud horn. By
the time you get to the front door, the kids will probably be halfway home. You
can sure save on the treats this way!
How it works:
Inside the mailbox is a screen door
closure to open and close the door of the mailbox. Then there is a 12 inch lawn
sprinkler body mounted horizontally that has the scare (a hand?) attached to the
riser which comes shooting out when activated. The doorbell just completes the
circuit to activate the device. Pretty simple, and very effective.
- 1 Mailbox, standard T1 size.
- Toro 12 inch 570 series pop-up sprinkler body.
- Toro 1/2 inch male elbow (for funny pipe).
- Toro 570 fixed spray nozzle, any kind will do.
- Garden Hose washer.
- 1 1/4 Pipe flange base.
- 3 foot piece of 1 1/4 PVC.
- 1 1/4 male to PVC adapter.
- Dish Washing machine solenoid valve and line cord.
- Washing machine hose to connect to valve and screen door closure and
- "L" shaped bracket.
- Screen door closure and hardware.
- Rubber hand or whatever you want to use for the effect, maybe a rat, use
- Assorted nuts and bolts and pipe clamps.
- Piece of 2x4 for mounting the sprinkler.
- Dryer spring.
- Compressed air to run the effect (compressor or refillable air tank.)
- Preparing the door opening cylinder: This
step is necessary to allow the door to open first. You will be attaching a
weak spring externally to allow the door to close automatically. First
remove the bleeder screw from the base of the screen door cylinder. This
will take any compressed pressure off the cylinder. Next, you must remove
the return spring from the inside of the cylinder. This will be fairly easy
to do. At the top of the cylinder you will see the ram coming through what
looks like a washer. This is really an inverted
cup which is there to retain the spring and guts of the mechanism. Use a
pair of needle nose pliers, diagonal cutters or regular pliers (I found that
the diagonal cutters worked best for me.) By slightly depressing one side of
the cup you will be able to get at the crimped end of the cylinder.
Carefully work your way around the cylinder, open the crimped end, and you
will be able to remove the cup, and then remove the spring. While doing this
step, remember that this system is under pressure from the spring - don't
let the piston and rod fly out and damage something - or someone!
On some closures, there may be a small spring inside the larger spring.
(Carl discovered that setup in the version he used, and he advises that you
leave the small spring in, if you encounter one.) Put the cup back in and
pull the ram out to approximately the location of the cup before you opened
the cylinder. Drill 2 small holes through the cylinder and cup, and secure
the cup in its original position with 2 sheet metal screws. This entire
operation only takes about 15 minutes. You will notice now that the ram can
easily be moved in and out. Replace the bleeder screw but do not tighten it
all the way. This step is necessary to allow the door to open first. You
will be attaching a weak spring externally to allow the door to
automatically close. This cylinder must operate with hardly any restriction.
- Installing the flange: Install
the flange in the bottom of the mailbox by drilling and bolting, install
the PVC to pipe adapter, then cut a hole in the center of the flange to
run the air hose and electric wire.
- Preparing the Toro sprinkler: The
Toro pop-up sprinkler body has 2 holes for attaching the water supply.
We will be using the one on the side so install the 1/2 inch male elbow
there, and plug the other hole. Unscrew the spray nozzle and put the
garden hose washer between it and the riser, this will cushion the riser
when it returns.
- Install the "L" bracket: This
bracket will hold the effect. Remove the adjusting screw from the
sprinkler nozzle. Using a sheet metal screw, mount the "L"
bracket so that the "L" is on top and facing backwards.
Attach your effect to the "L" bracket. Using 2 pipe clamps,
screw them into the 2x4 and attach the sprinkler to the 2x4 until
until the rear of the sprinkler is even with the end of the 2x4.
Attach the air hose to the sprinkler and a tee to the horn if you are
going to use one. Use another tee to branch off to the air supply and
the screen door opener. This completes the preparation of the
- Attaching the screen door cylinder: Attach
the screen door hardware that normally attaches to your door jam to
the inside front of the mailbox door. Mount it as close to one side
of the door as you can so it won't interfere with the effect. Attach
the other end to the side of the mailbox by drilling a hole in the
mailbox and bolting the stationary hardware to the inside. Note that
it becomes very tight working inside the mailbox, but if you take
the back panel off the mailbox it will be much easier. Slide the 2x4
into the mailbox until it is in the right position that the effect
will be just inside the closed door to the mailbox. Then drill
through the bottom of the mailbox and secure the 2x4 with screws.
- Install the return spring: Drill
a small hole in the side of the mailbox near the rear of the
screen door cylinder. From the inside of the mailbox insert one
end of the return spring into the hole. The other end will be
looped over the screen door mounting hardware. This will pull back
the mailbox door when the air is released.
- Complete the electric and air
circuits: Connect the air line to the
Washing machine solenoid. Try routing the air as follows: Output
of the washing machine solenoid to the screen door cylinder then
to horn and finally to the Toro sprinkler. Connect the input
side of the washing machine solenoid to your air supply. Connect
the electric supply cord, routing one side through a dummy
doorbell and then to the washing machine solenoid. I would not
use a real doorbell for this, go to your electrical supply house
or ask an electrician what you could use and still be safe. If
you don't want to use a doorbell, you could use a remote switch
to activate it.
- Final preparations: We
poured 4 to 5 inches of concrete into a 5 gallon bucket and
centered the 3 foot piece of 1 1/4 PVC vertically in it. When
it set up, we removed the bucket and drilled a hole large
enough to run the air supply and electric up and into the
mailbox. We put this hole just above the top of the concrete.
Glue the PVC to the PVC adapter and paint the pipe and base to
You must be very careful that no one is
in striking distance of the effect when it is triggered. A lot
of force is generated by the compressed air.
to my Halloween page.
design (c) by:
Lund Consulting Service
Phone: (631) 231-8790
by Lawrence H. Lund Last Modified on: November 2004