DIY Pneumatic Skeleton and Air Horn Gag to Scare Those Trick-Or-Treaters


[Rick Osgood] has been busy making more scaring gags for Halloween. This week he’s sharing great ideas for an air horn and pneumatic jumping skeleton, both actuated by 24 V sprinkler valves. These two new gags can easily be activated using [Rick’s] cardboard floor plate switch and three 9 V batteries cleverly snapped together in series for a 27 V supply (we can’t resist dropping in this link to a 2196 V supply from 9 V batteries just for fun).

The air horn construction is quite unique using a latex balloon strategically located as a reed valve for the air to vibrate over as it rushes out making a very loud honking sound. [Rick] then connected his manual bicycle pump to an air supply so that when an air valve is actuated the bicycle pump handle with a skeleton wired to it pops up. It then lowers back down via a bleed hole in the air line. Both the air horn and pneumatic pop-up skeleton seem simple to construct and his tests show them functioning perfectly.

Being the air storage chambers are small the re-trigger setup seems too repetitive to be practical for a continuous stream of Trick-Or-Treaters. Perhaps one could hide an air compressor with a long feed line to supply the gags? Plus, using an air compressor would come in handy for other scary blasts of air. Of course you would want to lower the compressor’s output regulator to safe levels so you don’t risk blowing apart your pop-up skeleton rig or any pipes.

Follow along after the break to see how to build these two great gags and get some tips from Mr. Safety.

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Tooth Fairy goes pneumatic


Kids’ fantasy figures are long overdue for some tech upgrades, so MAKE’s [Jeff Highsmith] carved a few holes in the walls and built a pneumatic transport system for his children to deliver their teeth to the Tooth Fairy. The project uses a system of 1.5″ PVC pipe with a central vacuum in the attic and two endpoint stations, one in each child’s room. Alternating which station has the closed valve and open door dictates the airflow path and shuttles a small plastic travel bottle from one station to the next.

Each station has its own iPhone interface that sends data to a Raspberry Pi and relays information, including a simulated map indicating the travel path taken by the tooth. Apart from controlling the vacuum via one of the Pi’s GPIO, the phone serves primarily as a visual distraction for the children while one parent sneaks off into the other room and replaces the tooth with some pocket change. [Jeff] made sure to add a locking door on each station to limit access and hopefully keep the mystery alive.

Watch his son’s face light up with sheer glee at the whole event in the video below, and regret that your childhood happened before the maker revolution. Then celebrate your adulthood with a beer fetching robot.

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What the inside of a pneumatic transport system looks like

While most of us are familiar with pneumatic transport systems by their use at drive-up bank windows, these systems are also commonly found in hospitals ferrying samples around. When [Aidan] was in the hospital, he asked how this series of tubes routed samples from many different floors to the lab and back again. Well, give him an old tube to play around with and he’ll eventually come up with a way to record the inside of one of these pneumatic tubes, giving some insight into how this system actually works.

When asked, a tech that uses this system on a daily basis described it as a very basic physical Ethernet that sucks and blows through rotary junctions and physical hubs to route packets to different areas of the building. [Aidan] wanted to record a tube’s travels, so he wired up a small HD camera, a bunch of LEDs, and a few batteries. Sending this recording sample container revealed some of how this pneumatic system works; the containers will travel forward and stop before reversing through one of the rotary switches. You can check out the flight of the container in the video below.

Of course there are other glimpses of how stuff travels through the unseen world of getting from point A to point B. Here’s a time lapse camera going on a trip via DHL just for kicks.

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60,000 RPM vacuum powered rotary tool was 3D printed


The whining of the turbines in the 3D printed pneumatic rotary tool might make your teeth hurt. When [Axodus] tipped us off about it he mentioned it sounded like a 747 taking off. But we hear a dentist’s drill when watching the demo video.

[Richard Macfarlane] published his design if you want to try building one for yourself. But you will need to do some machining in addition to printing the enclosure and the pair of turbines. The shaft of the tool needs to fit the bearings precisely. It accepts a center blue spacer with a red turbine on either side. This assembly is encapsulated in the two-part threaded blue body which has a flange to friction fit with the shop vacuum hose. The business end of the machined shaft was designed and threaded to accept the collet from a Dremel or similar rotary tool.

We wonder how much work it would be to re-engineer this to act as a PCB drill press?

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This Maglite is a BB Gun

Maglite BB Gun

This innocent looking Maglite houses a piston and barrel, making it into a functional pneumatic BB gun. A Maglite was chosen due to its high durability, and easy access to the internals. A schrader valve sticks out of the battery cap, which allows the gun to be charged using a standard fitting. A brass tube is used as the barrel, and a piston controls firing.

Firing the gun is simple. First, the whole thing is charged up to the desired pressure. Then the ammunition is inserted into the barrel. At this point, the rubber piston is held against the end of the barrel by the pressure in the gun. By pushing the pin of the valve in, the piston is able to move back slightly. This acts as the trigger, and causes air to rush into the barrel, firing the BB.

The results are fairly impressive. Using a chronograph, the speed of the BB was measured at 850 feet per second. Using the Gas Gun Design Tool simulator, it was estimated that the gun could fire at over 1000 feet per second, and maybe even break the sound barrier.

How to build an extremely powerful nerf gun

[TopCityGear] was trying out a piece of PVC as a blow gun barrel when he thought he’d try to give it a little more power than what his lungs could put out. What he came up with is this air-powered Nerf gun that definitely leaves a mark. The video after the break is a show-and-tell, a build log, and finally a demonstration of its power. He adds a nail to a Nerf dart and drives it through a board, then leaves a huge welt on his poor friends chest with a plain old foam dart. It reminds us of those riot guns that shoot bean bags.

The air is stored in that twelve-inch PVC reservoir. On the rear cap there’s a Schrader valve for pressurizing the tank with a compressor or even a bike pump. The grip is a gutted cordless drill whose battery doubles as the power source for the electric sprinkler valve which fires the gun. The screw fitting just in front of the hand grip lets him remove the barrel so that the projectile can be inserted.

This reminds us of that gun which shoots water-filled ping-pong balls.

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Controlling a spud gun with an Arduino

We’re a long way from the Aquanet-powered plastic pipe spud guns of our youth. [smirpab] over on the SpudFiles forum posted a work in progress of an amazing replica AS50 sniper rifle he’s building. This pneumatic cannon goes above and beyond any air-powered rifle we’ve seen with an Arduino that is able to switch between automatic, semi-automatic, and burst modes with an LCD display and a rate of fire control.

The mechanics of [smirpab]’s build are fairly normal for this level of pneumatic gun; it shoots 6mm plastic pellets from a smooth bore barrel with using air compressed to about 10 bar (145 psi). The electronics is where this project really shines, with an Arduino controlling the mode of fire (auto, semi-auto, and a 3-round burst), and the number of rounds per second adjustable with a pot.

A very cool project, and looking at the CAD renders of what [smirpab] completed project will look like, we can’t wait to see this build finished. As always, this build comes with the standard Hackaday “you’ll put your eye out, kid” warning. You can check out a video of [smirpab]’s piston after the break, along with a demo of the Arduino-powered control circuit going through all three firing modes.

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