Retrotechtacular: The Drama Of Metal Forming

It may seem overwrought, but The Drama of Metal Forming actually is pretty dramatic.

This film is another classic of mid-century corporate communications that was typically shown in schools, which the sponsor — in this case Shell Oil — seeks to make a point about the inevitable march of progress, and succeeds mainly in showing children and young adults what lay in store for them as they entered a working world that needed strong backs more than anything.

Despite the narrator’s accent, the factories shown appear to be in England, and the work performed therein is a brutal yet beautiful ballet of carefully coordinated moves. The sheer power of the slabbing mills at the start of the film is staggering, especially when we’re told that the ingots the mill is slinging about effortlessly weigh in at 14 tons apiece. Seeing metal from the same ingots shooting through the last section of a roller mill at high speed before being rolled into coils gives one pause, too; the catastrophe that would result if that razor-sharp and red-hot metal somehow escaped the mill doesn’t bear imagining. Similarly, the wire drawing process that’s shown later even sounds dangerous, with the sound increasing in pitch to a malignant whine as the die diameter steps down and the velocity of the wire increases.

There are the usual charming anachronisms, such as the complete lack of safety gear and the wanton disregard for any of a hundred things that could instantly kill you. One thing that impressed us was the lack of hearing protection, which no doubt led to widespread hearing damage. Those were simpler times, though, and the march of progress couldn’t stop for safety gear. Continue reading “Retrotechtacular: The Drama Of Metal Forming”

Retrotechtacular: Forging In Closed Dies

It is the norm for our Retrotechtacular series to concentrate on a technology that has passed out of use but is still of interest to Hackaday readers, so it is perhaps unusual now to feature one that is very much still with us. Drop forging is a technique for forming hot metal in dies under huge force, and while it is still a current technique the 1950s educational film we are featuring is definitely retro.

An automotive connecting rod, sectioned and acid treated to show the grain structure. (CC BY-SA 2.5)
An automotive connecting rod, sectioned and acid treated to show the grain structure. (CC BY-SA 2.5)

If you have followed our occasional series on blacksmithing, you’ll be familiar with the process of forming metal by heating it to a temperature at which it becomes malleable enough to deform under pressure, and using a hammer to shape it against an anvil. This process not only shapes the metal, but also forms its inner grain crystal structure such that with careful management the forging process can impart significant resistance to fatigue in the finished item. Think of drop forging as automation of the manual blacksmithing process, with the same metallurgical benefits but in which the finished product is shaped in a series of dies rather than by the blacksmith’s hammer. It loses the craft of the smith over the process, but delivers an extremely consistent result along with a high production turnover.

The film that we’ve placed below the break is an in-depth introduction to the industry in a very period style and with components for the automotive, aerospace, and defense industries of the day. It takes the viewer through the different types of press and examines the design of dies to produce in stages the required grain structure and shapes.

Of particular interest is the section on upset forging, a technique in which a piece of steel stock is forged end-on rather from above. The components themselves make the video worth watching, as we see everything from jet turbine blades to medical forceps in production, along with many parts from internal combustion engines. The smallest piece shown is a tiny carburetor part, while the largest is a huge aircraft carrier catapult part that requires a special vehicle to load it into the press.

Drop forging is generally the preserve of a large metalworking factory due to the size of the presses involved. But it’s not entirely beyond the capabilities of our community given the resources of a well-equipped hackerspace or blacksmith’s shop. My father made simple forging dies by assembling a basic shape in weld and pieces of steel stock before grinding it to his requirements and heat treating. Mounted in a large rotary fly press for repetitive small scale shaping and forming tasks in ornamental ironwork, I remember bumping them out from red hot steel bar in my early teens.

This is one of those techniques that’s useful to know about in our community, because while the need to manufacture significant quantities of ornamental ironwork may not come your way too often, it’s still worth having the capability should you need it. Meanwhile the video below the break should serve to provide you with enough heavy machinery enjoyment to brighten your day.

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Reducing Drill Bit Wear The Cryogenic Way

There are a lot of ways that metals can be formed into various shapes. Forging, casting, and cutting are some methods of getting the metal in the correct shape. An oft-overlooked aspect of smithing (at least by non-smiths) is the effect of temperature on the final characteristics of the metal, such as strength, brittleness, and even color. A smith may dunk a freshly forged sword into a bucket of oil or water to make the metal harder, or a craftsman with a drill bit might treat it with an extremely cold temperature to keep it from wearing out as quickly.

Welcome to the world of cryogenic treatment. Unlike quenching, where a hot metal is quickly cooled to create a hard crystal structure in the metal, cryogenic treatment is done by cooling the metal off slowly, and then raising it back up to room temperature slowly as well. The two processes are related in that they both achieve a certain amount of crystal structure formation, but the extreme cold helps create even more of the structure than simply tempering and quenching it does. The crystal structure wears out much less quickly than untreated steel, therefore the bits last much longer.

[Applied Science] goes deep into the theory behind these temperature treatments on the steel, and the results speak for themselves. With the liquid nitrogen treatments the bits were easily able to drill double the number of holes on average. The experiment was single-blind too, so the subjectivity of the experimenter was limited. There’s plenty to learn about heat-treated metals as well, even if you don’t have a liquid nitrogen generator at home.

Thanks to [baldpower] for the tip!

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Making A Mediaeval Nail

If for some reason I were to acknowledge the inevitability of encroaching middle age and abandon the hardware hacker community for the more sedate world of historical recreation, I know exactly which band of enthusiasts I’d join and what period I would specialise in. Not for me the lure of a stately home in Regency England or the Royal court of Tudor London despite the really cool outfits, instead I would head directly for the 14th century and the reign of King Edward the Third, to play the part of a blacksmith’s wife making nails. It seems apposite to pick the year 1337, doesn’t it.

The woman blacksmith forging a nail depicted in the Holkham Bible. British Library (Public domain)
The woman blacksmith forging a nail depicted in the Holkham Bible. British Library (Public domain)

Why am I so sure? To answer that I must take you to the British Library, and open the pages of the Holkham Bible. This is an illustrated book of Biblical stories from the years around 1330, and it is notable for the extent and quality of its illuminations. All of mediaeval life is there, sharply observed in beautiful colour, for among the Biblical scenes there are contemporary images of the people who would have inhabited the world of whichever monks created it. One of its more famous pages is the one that caught my eye, because it depicts a woman wearing a blacksmith’s apron over her dress while she operates a forge. She’s a blacksmith’s wife, and she’s forging a mediaeval carpenter’s nail. The historians tell us that this was an activity seen as women’s work because the nails used in the Crucifixion were reputed to have been forged by a woman, and for that reason she is depicted as something of an ugly crone. Thanks, unknown mediaeval monk, you really don’t want to know how this lady blacksmith would draw you!
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Retrotechtacular: Making Chains

We take the everyday materials of engineering for granted, as ubiquitous components rather than as complex items in their own right. Sure, we know that an integrated circuit represents the pinnacle of a hundred years’ development in the field of electronics, but to us it’s simply a black box with some wires. Even with more basic materials it’s easy to forget the work that goes into their manufacture, as for example with the two videos below the break. They both take a look from a very different angle at the creation of the same product: metal chain. However, the approaches couldn’t be more different as the two examples are separated by about a century and with vastly different techniques and material.

The first film follows the manufacture of the chain and anchor that would have been found on a ship around the turn of the twentieth century. One of the text frames mentions Netherton Works, allowing us to identify it as being filmed at N. Hingley & Sons, a specialist anchor and chain manufacturer based in the area to the west of the English city of Birmingham known as the Black Country. It’s a window on a manufacturing world that has entirely disappeared, as large gangs of men do almost every task in the process by hand, with very few automated steps. There is scant regard for health and safety in handling the huge pieces of red-hot metal, and the material in question is not the steel we’d be used to today but wrought iron. The skill required to perform some of the steps such as forge-welding large anchor parts under a steam hammer is very significant, and the film alone can not convey it. More recent videos of similar scenes in Chinese factories do a better job.

The other video is contemporary, a How It’s Made look at chain manufacture. Here the chains involved are much smaller, everything is done by automated machinery, and once we have got over marveling at the intricacy of the process we can see that there is far more emphasis on the metallurgy. The wire is hard drawn before the chain is formed, and then hardened and annealed in a continuous process by a pair of induction heaters and water baths. I’m trying really hard to avoid a minor rant about the propensity of mass-market entertainment such as this for glossing over parts of the process. A keen eye notices that each link has become welded but we are not shown the machine that performs the task.

Most of us will never have the chance of a peek into a chain factory, so the medium of YouTube industrial films and videos is compulsive viewing. These two views of what is essentially the same process could not be more different, however it would be wrong to assume that one has replaced the other. There would have been mechanised production of small chains when the first film was made, and large chains will still be made today with fewer workers and from arc-welded steel rather than wrought iron. Plants like the Hingley one in Netherton may have closed in the 1980s, but there is still a demand for chains and anchors.

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Hand-Forged Cases Make Nixie Clocks Into Works Of Art

Both “Nixie” and “Steampunk” are getting a bit overused. It’s hard to count the number of clock projects we’ve seen recently that combine the two, and normally we’d be loath to feature yet another variation on that theme without a good reason. This is a good reason.

The single-digit Nixie clocks that [Claes Vahlberg] built are, simply put, works of art. There’s a small version of the clock, featuring a single IN-16 Nixie, and a larger version that uses a Dalibor Farny custom Nixie, a work of art in its own right. Each clock has features like time and date, temperature and barometric pressure, and even days remaining in the current lunar cycle. The cases for the clocks, though, are the real treat. Hand forged from steel, they remind us of steam whistles on top of a boiler.

[Claes] doesn’t have many details on the build process — we’ve been in contact and he says he’s working on documentation — but it doesn’t matter. As if all that weren’t enough, the clocks are controlled by a remote, which has its own IN-16 tube and is motion controlled. The last bit is a nice touch since there are no buttons to distract from the smooth lines of the hammered metal case.

We gush, but we think this one really shines. That’s not to take anything away from previous Nixie-steampunk mashups, like this single-digit clock or this solar power meter. But these clocks are a step beyond.

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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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