Retrotechtacular: The Iron Giants That Built The Jet Age

In the closing months of World War II, the Axis and the Allies were throwing everything they had at each other. The tide was turning to the Allies’ favor, but the Germans were showing a surprising resilience, at least in terms of replacing downed fighter and bomber aircraft. When the Allies examined the wreckage of these planes, they discovered the disturbing truth: the planes contained large pieces forged from single billets of metal, which suggested a manufacturing capability none of the Allies possessed and which allowed the Germans to quickly and cheaply make better and faster planes.

When the war was over, the Allies went looking for the tools the Germans had used to make their planes, and found massive closed-die forging presses that could squeeze parts out of aluminum and magnesium alloys in a single step. The Soviets carted off a 30,000 ton machine, while the Americans went home with a shipload of smaller presses and the knowledge that the Russians had an edge over them. Thus began the Heavy Press Program, an ultimately successful attempt by the US military to close a huge gap in strategic manufacturing capabilities that [Machine Thinking] details in the excellent video below.

One doesn’t instantly equate monstrous machines such as the Mesta 50,000-ton press, over nine stories tall with half of it buried underground and attached directly to bedrock, with airplane manufacture. But without it and similar machines that came from the program, planes from the B-52 to the Boeing 747 would have been impossible to build. And this isn’t dead technology by any means; sold to Alcoa in 1982 after having been operated by them for decades, the “Fifty” recently got a $100 makeover after cracks appeared in some castings, and the press and its retro-brethren are still squeezing out parts for fighters as recent as the F-35.

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Building a Knife by Hand is just as Hard as you Think

Carl Sagan once said: “If you wish to make an apple pie from scratch, you must first invent the universe.” In other words, the term “scratch” is really a relative sort of thing. Did you grow the apples? Did you plant the wheat to make the flour? Where do you keep your windmill, incidentally? With Carl’s words in mind, we suppose we can’t say that [Flannagill] truly built this incredible knife from scratch, after all, he ordered the sheet steel on Amazon. But we think it’s close enough.

He was kind enough to document the epic build in fantastic detail, including (crucially), the missteps he made along the way. While none of the mistakes were big enough to derail the project, he mentions a few instances where he wasted time and money trying to take shortcuts. Even if making your own knives at home isn’t on your short list of summer projects, we’d wager there’s something in this build log you can learn from regardless.

So how does one build a knife? Slowly and methodically, if what [Flannagill] has written up is any indication. It started with a sketch of the knife on a piece of paper, the outline of which was then transferred to a piece of tool steel with nothing more exotic than a permanent marker. An angle grinder was then used to follow the outline and create the rough shape of the final knife.

From there, the process is done almost entirely with hand files. Here [Flannagill] gives one of his most important pieces of advice: don’t cheap out on the tools. He bought the cheapest set of files he could, and paid the price: he says it took up to 14 hours to complete just one side of the knife. Once he switched over to higher quality files, the rest of the work went much faster.

After filing and sanding the knife blank, it went into a charcoal fire to be hardened, followed by a total of 4 hours in a 200 C (~400 F) oven to heat temper it. Finally the handle pieces (which are officially known as “scales”) were attached, and finished with considerably less labor intensive woodworking methods. The final result is a gorgeous one of a kind specimen that [Flannagill] is rightly very proud of.

If you’re worried this process looks a bit too quick and easy for you, don’t worry. You can always go the [Bil Herd] route and make a forge out of your old sink if you’d rather start your apple pie a bit closer to the tree.

Shutter Bug Goes Extreme with Scratch-Built Film Camera

Should a camera build start with a sand mold and molten aluminum? That’s the route [CroppedCamera] took with this thoroughly impressive camera project.

When we think of cameras these days, chances are we picture the ones that live inside the phones in our pockets. They’re the go-to image capture devices for most of us, but even for the more photographically advanced among us, when a more capable camera is called for, it’s usually an off-the-shelf DSLR from Canon, Nikon, or the like. Where do hand-built cameras fall in today’s photography world? They’re a great way to add a film option to your camera collection.

[CroppedCamera] previously built a completely custom large-format view camera, but for this build he decided that something a bit more portable might do. The body of the camera is scratch-built from aluminum, acting as the lightproof box to hold the roll film and mount the leaf-shutter lens. There’s an impressive amount of metalwork here — sand casting, bending, TIG welding, and machining all came into play, and most of them new skills to [CroppedCamera]. We were especially impressed with the shrink-fit of the lens cone to the body. It’s unconventional looking for sure, but not without its charm, and it’s sure to make a statement dangling around his neck.

It’s tough to find non-digital DIY camera builds around here — best we could do were these laser-cut plywood modular cameras. Then again, you can’t beat this wearable camera for functional style.

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Buying Machine Tools: Foreign or Domestic, New or Used?

The last time we discussed machine tools, we talked about how to choose the size of the new metalworking lathe that your wallet is itching to pour itself into. The next big decision to make is “new or used?” If you’re in North America, this question has a lot of overlap with the classic question “Import or American?”. The answer boils down to what your needs are, and what you want to get out of this machine.

If you are new to machining, and want to learn the skills, I recommend starting with an Asian import machine. If you’re careful which one you select, you’ll end up with a very reasonably priced lathe that can do precise work right out of the crate. If your interest is in learning how these tools work, and in doing a restoration project, an old American machine is a great choice. Let’s look at these two routes in more detail.

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Building a Tricorder Prop Worthy of Mr Spock

We’ve all been there. You want to assemble a proper Star Trek: The Original Series landing party prop set, but the TOS tricorders you can find on the market are little more than overpriced toys. Imagine the embarrassment of beaming down to Cestus III with a plastic tricorder. The Metrons wouldn’t have even bothered with the trial by combat with such a sorry showing.

Unhappy with the state of Star Trek props, [Dean O] decided to take matters into his own hands. He purchased a TOS tricorder from Diamond Select Toys and set out to modify it into something a bit closer to Starfleet standards. Anything painted metallic silver on the toy was replaced with a machined aluminum duplicate, adding some much needed heft. He even spruced up the controls and display.

To start, [Dean] stripped the tricorder down, separating all of the silver plastic parts and finding aluminum stock that was close enough to the desired dimensions. This ended up being .125″ plate for the sides, and .500″ bars for the horizontal dividers. To make the side panels he placed the original plastic parts over the aluminum, marked the mounting holes with a punch, and used the belt sander to shape them.

[Dean] then put in a more screen accurate Moire disc, and went as far as to get real watch crowns for the buttons (just like the prop used in the show). In a particularly bold move, he even drilled out the center of watch crowns to install plastic light pipes for LED illumination.

Last year we saw a build that crammed a Raspberry Pi into the same Diamond Select tricorder toy to excellent effect. Now somebody just needs to combine both projects and they’ll have the slickest tricorder in the Alpha Quadrant.

The Fine Art of Acid Etching Brass

If you were building a recreation of the James Watt micrometer, where would you start? If you’re [rasp], the answer would be: “Spend a year trying to find the best way to make etched brass discs.” Luckily for us, he’s ready to share that information with the rest of the world. While it’s rather unlikely anyone else is working on this specific project, the methods he details for getting museum-quality results on brass are absolutely fascinating.

The process starts with sanding down the bare brass and applying a layer of clear packing tape to the metal. [rasp] then covers the piece with LaserTape, which is a special tape designed to make laser-cut masks for sandblasting. But the masking principle works just as well for painting or chemical etching.

With the LaserTape in place, the piece is then put into the laser and the mask is cut out. Once cut, there’s the tedious task of peeling off all the cut pieces of tape, which [rasp] does with a dental pick. Once the pieces are pulled off, the brass is ready for its acid bath.

Anyone who’s etched their own PCB with ferric chloride will recognize these next steps. The piece is put into the acid bath and agitated every 10 minutes or so. It’s interesting to note that [rasp] places the piece in the bath upside-down, using little 3D printed “feet” to suspend the brass sheet off the bottom of the container. This allows the debris from the etching process to fall down and away from the piece. After about an hour out in the sun, the piece is pulled out of the bath and carefully washed off.

Once clean off, the piece is sprayed with black spray paint to darken up the etched areas. The moment of truth comes when the paint has dried and the layers of tape are carefully peeled back to reveal the etching. [rasp] then wet sands the piece with 1000 and 2000 grit paper, and a final pass with polishing compound brighten up the surface to a mirror-like shine. It’s quite a bit of manual labor, but the end result really is spectacular.

In the video after the break, [rasp] breaks down the entire process, including the additional machine work required to turn these brass plates into functional components of the final machine. As an added bonus, he even includes a lot of his failed attempts in an effort to keep others from making the same mistakes. Something we love to see here at Hackaday.

The process used here is similar to the snazzy brass name plates we showed earlier in the year, and has even been done without a laser using photoresist.

[via /r/DIY]

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3D-Printed Punch and Die Stand up to Steel

When you think of machine tooling, what comes to mind might be an endmill made of tungsten carbide or a punch and die made of high-speed steel. But surely there’s no room in the machine tool world for 3D-printed plastic tools, especially for the demanding needs of punching parts from sheet metal.

As it turns out, it is possible to make a 3D-printed punch and die set that will stand up to repeated use in a press brake. [Phil Vickery] decided to push the tooling envelope to test this, and came away pleasantly surprised by the results. In fairness, the die he used ended up being more of a composite between the carbon-fiber nylon filament and some embedded metal to reinforce stress points in the die block. It looks like the punch is just plastic, though, and both were printed on a Markforged Mark 2, a printer specifically designed for high-strength parts. The punch and die set were strong enough to form 14-gauge sheet steel in a press brake, which is pretty impressive. The tool wasn’t used to cut the metal; the blanks were precut with a laser before heading to the press. But still, having any 3D-printed tool stand up to metal opens up possibilities for rapid prototyping and short production runs.

No matter what material you make your tooling out of, there’s a lot to know about bending metal. Check out the basics in our guide to the art and science of bending metal.

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