Author: Al Williams

4475 Articles

A Different Kind Of 3D Printer: Desktop Holograms

March 12, 2021 by 38 Comments

Holograms aren’t new, but a desktop machine that spits them out could be available soon, presuming LitiHolo’s Kickstarter pans out. The machine will have a $1600 retail price and fits in a two-foot square. It can generate 4×5 inch holograms with 1mm hogels (the holo equivalent of a pixel).

The machine allows for 23 view zones per hogel and can create moving holograms with a few seconds of motion — like the famous kiss-blowing holograms.

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Historical Hackers: Hero Builds Vending Machines

March 12, 2021 by 14 Comments

We tend to think of mechanical contrivances as products of the industrial revolution and true automation as something computers handle. Yet even before computers, automation existed — using timing motors and cams and other mechanical contraptions. But it might surprise you to know that there was actually some sophisticated automation going way back. Really way back, invented in a world without computers, CAD software, or even electricity. For example, around 50 AD an inventor named Hero — sometimes known as Heron — built machines powered by steam and wind. His inventions included vending machines and music players.

It is hard to imagine what kind of music player or, indeed, vending machine you could build in 50AD. Some of Hero’s inventions were used in temples to, for example, dispense holy water. Others were used in theater to do things like automatically lighting a fire or creating thunder effects. There was even an entirely automated puppet show that used knotted ropes to put on a ten-minute production with no human assistance.

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3D Printer Air Compressor Is A Wankel

March 11, 2021 by 31 Comments

We wonder if mechanics are as annoyed when we say “engine” as we get when someone talks about a “computer” or a “radio.” Sure, you know what all three of those words mean, but there are many different kinds of radios, computers, and engines. In [3DprintedLife’s] case, he made a compressed air engine of the Wankel style.

The Wankel — a rotary engine — is most famous for its use in some Mazda cars. If you’ve done a lot of 3D printing, you know that creating an air-tight piston on a 3D printer is no mean feat. Of course, he didn’t do it right off the bat. It took what looks like a number of iterations to get it going, and he shares some of what he learned doing this project.

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3D Printed Lenticular Lens Makes 3D Display

March 10, 2021 by 32 Comments

[Bitluni] has been experimenting with resin printing lenses — in particular, lenticular lenses. You’ve probably seen lenticular lenses before in 3D greeting cards or children’s books. By presenting a slightly different image at different angles, your eyes perceive stereo vision giving the illusion of depth. You can see his results in the video below.

Honestly, even if you don’t want to make a display like this yourself, the demonstration of how a lenticular lens works using a laser is worth watching. Sure, you know in theory what’s going on, but seeing it visually exposed is great.

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Laser Focus Made Easier With IR Filter

March 9, 2021 by 13 Comments

If you’ve used a diode laser engraver or cutter, you know that focus is critical. You’d think it would be relatively simple to get a sharp focus, but it isn’t that simple. [Makers Mashup] shows in a video how to use an adjustable IR filter to cut out all the light bleed to get a sharp image to make focusing simpler.

The filter he shows adjusts from 530nm to 750nm and is made to screw into a 72mm lens, but it works fine with your eyeballs, too. [Makers Mashup] says he’ll eventually make a stand for it so he can look through it with both hands free.

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Laser Zap That Mosquito

March 8, 2021 by 98 Comments

When we first heard of [Ildar Rakhmatulin’s] plan to use OpenCV on a Raspberry Pi to detect mosquitos and then zap them with a 1 watt laser, we thought it was sort of humorous. However, the paper points out that 700,000 people die each year from mosquito bites — we didn’t verify that, but according to the article that’s twice the number of people murdered each year. So the little pests are pretty effective assassins.

It looks as though the machine has been built, at least in a test configuration. A galvanometer aims the death ray using mirrors, and with the low power and lossy mirrors the mosquitos can only be a small distance from the machine — about a foot.

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The B-2 Bomber: Those Who Forget History Are Doomed To Reverse Engineer It

March 7, 2021 by 82 Comments

The Drive had an interesting post recently, about someone noticed a procurement from the U. S. Air Force to reverse engineer the B-2 bomber’s Load Heat Exchanger (whatever that is). You’d think if the Air Force wanted to reverse engineer something, they’d be looking at another country’s aircraft. What can this mean?

Presumably, the original plans for the system have been lost, or maybe the company who made them is long gone and the tooling to create new ones along with it. Then again, maybe the assembly needs parts that you can no longer get. The Drive has another interesting speculation: perhaps the plans were so secret that were accidentally destroyed.

You don’t hear much about the B-2. There are only 20 left of the 21 built, at least that we know about. Original plans in the 1980s called for 132, but the end of the Cold War spelled the end for the stealth bomber. They get an overhaul every nine years. The Drive also speculates that this may be part of the Air Force’s desire to digitize spare parts and use 3D printing, but — honestly — it doesn’t sound that way to us. Especially since the fleet will retire no later than 2032, so whatever is replaced is only needed for a decade.

If you think you want to have a go, here’s the help wanted ad from the Air Force. If you read the text, it’s pretty clear they have some defective units that need replacement and it sounds like no one knows how to do it with existing materials. Not many of us get to design things that are still working nearly three decades later. Keeping a supply of parts and even know-how for something built in the 1990s isn’t trivial. Something to think about if you design something with a long service life.

The B-2 is a stealth bomber and while one did crash, it wasn’t shot down. The F-117A — the stealth fighter — was shot down against all odds, though. While the B-2 appears to be quite a plane, we prefer our bombers a little bit older. Still, you might enjoy the video below about the B-2’s chief engineer, although he doesn’t mention the Load Heat Exchanger.

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