Vacuum pressure bazooka

This vacuum pressure cannon is a design unlike any we’ve seen before. At first look it seems to have the components you see in a potato gun. But those use a combustion process to launch the projectile. This instead uses the sudden release of a vacuum.

About three minutes into the demo video below we get a look at the “ignition” system. It’s pretty scary in that a couple of really powerful springs are pulling a collar along the barrel toward your face. This is actually meant to dislodge the plug in the back which is holding vacuum in the barrel. The pressure difference causes a sudden inrush of air which shoots the 1.5 inch projectile out the front of the bazooka.

[Mr. Teslonian] built his own hand powered vacuum pump for loading the weapon. This was done with a pair of PVC pipes that fit inside of one another, and a plunger made from wood and leather. The PVC and wood projectile seals in the barrel using a skirt made from duct tape. After breech loading the projectile and plugging the back of the barrel, he layers aluminum foil over the business end and pumps up a high vacuum. His test firing is not from the shoulder, and he only gets one shot because the slug hit the target so hard it was destroyed. This thing really needs to be vehicle mounted!

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Biodiesel equipment hacks


[Oldman] took on a biodiesel project for some friends a few years ago. A fully operational processing rig was never achieved, but he did document some of the successful hacks he came up during the project.

The idea is to reclaim the waste oil from restaurants and burn it in your modified racing motorcycle or other mode of transportation. That makes it sound easy, but have you ever seen what happens to bacon fat after it cools? Granted, we’re talking oil from vegetable sources but the same type of coagulation presents itself. Pumping it through a processing rig becomes especially tough in the winter, and that’s why [Oldman] came up with the heated pump head on the right. It’s got three connections; two are part of a loop of copper tubing, allowing 150 degree water to be circulated to liquefy the grease. The third connection sucks up the melted oil. You also need to regulate the water content of the fuel. The inset images of a salad dressing jar are his test runs with applying vacuum to dehydrate the fuel. He learned that it needs to be heated slightly to reduce foaming. He had planned to scale up this concept to apply vacuum to fuel stored in propane tanks.

Thermocouple vacuum gauge teardown


We don’t know how [Ben Krasnow] gets his hands on so much cool hardware. This time around is a bit of vintage tech: a thermocouple vacuum gauge.

The part seen above, and represented in the schematic, is the sensor side of things. This is interesting enough by itself. It has an air chamber with an electric heater element in it. When air is present it dissipates the heat, when under vacuum the heat builds and causes the thermocouple to generate some voltage on its connections.

Keep watching his presentation and things get a lot more interesting. The original unit used to measure the sensor is a throwback to the days when everything had sharp corners and if you were running with scissors you’d eventually teach yourself why that’s not such a good idea. The designers were rather cavalier with the presence of mains voltage, as it is barely separated from connections grounding the case itself.

Want to see some of the other cool equipment he’s got on hand? How about a CT scanner he built.

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Wet spill vacuum cleaner attachment


You’ve got to hand it to [Lou], not only does he know how to build simple items, he also knows how to sell their worth. Here’s a wet spill vacuum cleaner attachment which you can build on the cheap. A picture of the final product fails to have the same impact as his video showing its use in cleaning up a simulated cat disgorging from the carpet.

From the picture we’re sure you’ve already figured out how it work. The air and damp matter come in one side and are dropped into the jar as the air is sucked out the other. [Lou] suggests raiding your recycling bin for the jar. The intake and outflow are both pieces from a PVC P-trap intended for a sink drain. They have a threaded flange which keeps the part from pulling all the way through the 1.5″ holes drilled in the lid.

This is going to work best with a high-flow shop vacuum. So while you’ve got the tools out, why not build a dust separator as well?

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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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Printed vacuum pump muffler quiets the lab


[Joel] made a brilliant improvement to his shop. If you think about it, most folks would hear a loud vacuum pump and either tolerate it or put in some ear plugs. But [Joel] heard a loud vacuum pump and thought: hey, I can fix that! His solution was to design and print his own muffler.

He did a bit of research on the topic and found that design complexity runs the gamut based on the application. For instance, you don’t want to affect the airflow of a vehicle’s exhaust too much or you will take a horsepower (and efficiency) hit for it. In this case the vacuum pump making all the noise has a relatively low airflow so that is not a concern. What he ended up doing is designing a baffle that will help cushion the vibrations in the airy by piping it through a maze of channels. The end result drops from about 92 dB to 82 dB. That might not seem like much, but decibel measurements aren’t linear so it ends up having a great effect. Hear for yourself in the video after the break.

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[Lou’s] haircut really sucks

Ah yes, at some point a brilliant inventor combined the electric trimmer with a vacuum cleaner and the art of cutting hair was never the same again. [Lou] is showing us how to give a haircut that really sucks up the waste. And he did it using rubbish he had lying around.

Most people will recognize this as a DIY version of the Flowbee. Not surprisingly, you can still buy one of those if you want, but [Lou] is looking for a vacuum cutter for trimming his dog’s hair so he’s not about to shell out cash for it. He already has the trimmer, and just needed a way to attach the vacuum hose to it. In the image above you can see the grey crevice attachment for his vacuum. He taped it onto the trimmers, then cut a plastic soda bottle to use as a hood near the business end of the trimmer. It’s all wrapped in packing tape to hold everything in place and seal around the joints. You can see it in action in the clip after the break.

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