Make Your Own Pneumatically Actuated Halloween Monster

Make Your Own Pneumatically Actuated Halloween Monster
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Nothing beats the excitement of seeing a monster that -- like a movie special effect -- lunges at trick-or-treaters on its own. Making your own pneumatically actuated (or in plain English, air-powered) Halloween monster, alien, scarecrow or puppet doesn't require a load of cash or a degree in mechanical engineering. Whenever you press a hidden button, your monster comes to life. Indeed, Shane Crider from AutomationDirect, a parts supplier for props like pneumatic monsters, says that you can build your own manually-controlled Halloween prop for not much more than $100. And if you have some experience with wiring, you can add a motion detector for a fully automated monster., Campbell Hausfeld

To make a manually controlled creature, you'll need an air compressor, a pneumatic air cylinder, a manual control valve (like a joy stick or foot pedal), and some tubing and fittings to connect the creature to the control valve and air cylinder. In addition to those basics, you will also want to add a silencer to the exhaust ports to keep the noise down when air is escaping from the system., Campbell Hausfeld

An automated creature uses essentially the same system as the manual setup, except that you need something to trigger the monster's movement. Instead of a joystick or foot pedal, you can use an electrically powered controller connected to a light sensor. When someone passes in front of the light sensor, your prop will lunge or leap out automatically.

This basic pneumatic system works with air pressure. Air pressure is created in the compressor, which connects to a controller. When you activate the controller -- by moving the joystick, for example -- air passes through the controller to the air cylinder (which is the component that actually moves the prop). When you release the joystick, the controller releases the air.

You can use plastic tubing (usually 1/4-inch diameter) to connect the compressor to the controller and to connect the controller to the cylinder. And becuase the devices usually have threaded holes, you'll need to screw in fittings to hold the tubing. Check the thread size of each device before you buy the fittings and tubing.

If the pneumatic cylinder looks familiar, it's probably becuase you've seen something just like a million times on your own screen door. Your door's cylinder uses air pressure to slow the door when it closes.

When you force compressed air into a cylinder attached to your Halloween monster, the piston inside the cylinder is forced out, which moves your prop. The end of the piston is threaded, so you can screw this into a nut attached to the prop. For a homemade monster or a puppet that can be moved with strings, screw a nut to the end of the piston and then tie the string or a thin wire to the thread.

Depending on which controller you use, it most likely has more ports than you need. This joystick has two outgoing ports (A and B), one incoming port (P) and two exhaust ports (R and S). Screw a fitting into one of the outgoing ports (A) and connect it to the cylinder with plastic tubing. Screw another fitting to the incoming port (P) and connect it to the compressor with plastic tubing. Put a silencer on one of the exhaust ports (R) to reduce the noise of escaping air. Put plugs on the unused outgoing ports to keep dust and debris from getting into the controller.

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In most cases, you won't need as much air pressure as your compressor can provide you. Too much air pressure can prematurely wear out the pneumatic components, make the prop move too quickly, or even blow out a seam in your monster. To avoid this problem, install an adjustable speed control fitting on the end of the cylinder. You can then turn its screw to get the right amount of air flow so the prop moves smoothly.

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When activating a manually controlled creature, you can keep yourself out of sight by hiding under a table, around a doorway, or in some cases directly behind your prop. If you are using a full-sized mannequin style prop, for example, you can just place a curtain behind it and then hide behind the curtain.

If you want to automate your pneumatic system, use an electrically operated solenoid valve instead of a manual controller. Wire the valve to a photo sensor. When someone passes by the photo sensor, it will activate the valve, which in turn activates the prop. When the person moves away from the sensor, the valve turns off, releasing the air pressure from the cylinder and retracting the prop to the position it was in before.

Wiring the photo sensor and the electrically operated solenoid valve is not extremely complex, but it does require some skill and experience with electricity. If you don't have these skills, don't try this on your own.

To connect these components, wire the sensor and the solenoid valve controller to either a DC or AC power supply. Place the photo sensor where you expect people to arrive, like at the top of your porch stairs. When someone walks in front of the photo sensor, the prop will automatically move without you having to stand there waiting.

With a few additional uprades, you can have even more control over your monster's animation. A programmable PLC controller connected to two small solenoids, or a 3-port 5-position valve gives you the ability to pre-program the animation using your computer. For example, you could have it move in and out at varying distances and varying speeds when someone walks by. A PLC controller like the PLC Click can control a dozen or more props on your porch, each with different ranges of motion and speeds.

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