Water-blob Launcher

December 3, 2010 by Mike Szczys 39 Comments

This rifle-shaped water cannon looks great and packs a big punch. We guess you could say that it’s a water balloon launcher, but the balloons are torn off and drop like the wad from a shotgun shell when fired. So we think this launches water blobs, or orbs, or something along those lines.

[Wolf] built it using PVC and some brass fittings that allow for the injection of compressed air. There’s a slick valve system that he developed which we don’t get a great look at in the build pictures. Fortunately, there’s an animated GIF that shows the various stages. Using his valve there’s no need for any electrical system like a lot of other pneumatic launcher systems use.

Just like the water-filled ping-pong gun, you’ve got to be careful with this thing. As you can see in the clip after the break there’s lethal force behind these projectiles. Especially when [Wolf] swaps out the water balloons for big steel darts.

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BendDesk Multi-touch Furniture

December 3, 2010 by Mike Szczys 23 Comments

The BendDesk is a horizontal and a vertical multi-touch display connected as one curved surface. Think of it as a smart white-board and a multi-touch desk all in one. It can be used to sort and edit information, or to play games. Check out “Bend Invaders”, a game demonstrated in the video after the break. When you touch two fingers to the display the two points are used to aim a laser at the oncoming monsters.

The system uses a combination of two projectors shining on the surface from underneath and behind. A series of LEDs around the edges of the display bathe it in infrared light. Three cameras with IR filters peer at the underside of the acrylic surface and detect touches by distinguishing variances in the IR pattern through a process called Frustrated Total Internal Reflection. If you’re interested in more of the math and science involved there are a couple of papers available from the project site linked at the top of this post.

We’ve seen so many displays using the Kinect lately, it’s refreshing to see one that doesn’t.

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Vacuum Forming At Home

December 2, 2010 by Mike Szczys 50 Comments

A little dumpster-diving let [Nick Skvarla] build his vacuum form machine for around $5. He pulled a vacuum cleaner out of the trash, which was tossed away because of a broken power plug. He put it into a box which had been sealed with spray foam and used a piece of pegboard for the top side of the enclosure. He takes a piece of 40 mil PETG plastic from the hobby shop and mounts it in a wooden frame. That goes into the oven on broil until the entire sheet is sagging, then onto the vacuum former. Above he’s making forms out of some figurines which he’ll walk you through in the video after the break.

There’s a whole world of manufacturing processes that use these forms as a starting point. What would you use this for?

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Make Your Own Solenoids, Then Play The Xylophone

December 2, 2010 by Mike Szczys 25 Comments

Learn to manufacture your own solenoids and then use them to play the xylophone by watching the tutorial video after the break. [Humberto Evans] and the team at Nerd Kits do a great job of not only manufacturing the coils, but the xylophone itself. The bars are machined from some aluminum stock and they take you down the rabbit hole with they why’s and how’s of engineering the keys.

We’re unlikely to replicate this machining process but the solenoids are another story all together. Starting at about 3:30 you can learn about designing, building, and using these little marvels. They’re basically an electromagnetic cuff with a metal slug in the middle. The solenoid seen above uses a body milled from HDPE and wrapped with magnet wire. The slug in the center is steel, with a few rare-earth magnets at the top. When you run current through the coil it repulses the magnets on the slug, witch then strikes the xylophone key. Using a MOSFET and a protection diode, actuating them is as simple as sending a digital high from your microcontroller of choice.

We’ve seen solenoids used to play a vibrophone before, but those were commercial units. Making your own hardware is far more hardcore.

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Heater For Bending Acrylic

December 2, 2010 by Mike Szczys 22 Comments

We like using acrylic in our projects but there are a couple of tricky techniques, particularly getting clean cuts for glued edges and bending the material into curves. [Giorgos Lazaridis] has a great solution to the latter, a dedicated acrylic heater. Instead of using an oven to warm the material for bending he’s using localized heat produced by a high-powered lamp pulled from an old laser printer. The next part of his solution is to keep the heated area of the acrylic as small as possible. This was achieved by creating heat sinks on either side of the bulb. The metal bars seen above have water running through them to help isolate the softening of the material to a narrow strip. See how well this system works in the video after the break.

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Steam-powered Rickrolling

December 2, 2010 by Mike Szczys 28 Comments

This is a steam-powered record player; awesome. But wait, that’s not all. Watch the video after the break for about two and a half minutes and you’ll realize that it’s also a Rickroll. No, you’re not getting baited into clicking through to Rick Astley’s music video, the LP that’s playing on the turntable is a copy of “Never Gonna Give You Up”; all kinds of awesome.

This all started with a steam engine machined from a stainless steel bolt and a brass cylinder. It was tested using compressed air before building the boiler. But what’s a steam engine without a purpose? The problem with using a steam engine as a turntable motor is speed control. This is where we move to modern technology, using an Arduino to measure the RPM and adjust the steam engine using a servo motor.

The builder makes a comment that this sounds terrible, but considering it’s steam-powered we think it sounds just fine.

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J1: A Small, Fast, CPU Core For FPGA

December 1, 2010 by Mike Szczys 25 Comments

[James Bowman] of the Willow Garage published a paper on his J1 CPU core for field-programmable gate arrays. This was originally developed and used for the Ethernet cameras on the PR2 (you know, that incredibly expensive beer delivery system?) robot. It uses a 16-bit von Neumann architecture and lacks several processor features you’d expect a CPU to have such as interrupts, multiply and divide, a condition register, and a carry flag. None-the-less, its compact at just 200 lines of Verilog and it can run at 80 MHz. [James] compares the J1 to three different FPGA CPU Cores commonly used and discusses how the system is built in his 4-page paper that has the details you’re interested in but won’t take all day to dig through.