Drilling holes is easy; humans have been doing it in one form or another for almost 40,000 years. Drilling really tiny holes in hard materials is more challenging, but still doable. Drilling deep, straight holes in hard materials is another thing altogether.
Luckily, these days we have electric discharge machining (EDM), a technique that opens up all kinds of possibilities. And just as luckily, [Ben Krasnow] got his hands on some EDM gear to try out, with fascinating results. As [Ben] explains, at its heart EDM is just the use of a small arc to ablate metal from a surface. The arc is precisely controlled, both its frequency via an arc controller, and its location using CNC motion control. The arc controller has always been the sticking point for home EDM, but the one [Ben] tried out, a BaxEDM BX17, is squarely aimed at the small shop market. The whole test platform that [Ben] built has a decidedly home-brew look to it, with a CNC gantry rigged up to a water tank, an EDM drill head spinning the drill rods slowly, and an airless paint gun providing high-pressure process fluid. The video below shows that it works remarkably well nonetheless.
While we’re certainly keen to see [Ben]’s promised videos on EDM milling and cutting, we doubt we’ll line up to shell out €2,950 for the arc controller he used. If you have more courage than money, this mains-powered EDM might be a better fit.
Blacksmiths were the high technologists of fabrication up until the industrial revolution gained momentum. At its core, this is the art and science of making any needed tool or mechanism out of metal. Are you using the correct metal? Is the tool strong where it needs to be? And how can you finish a project quickly, efficiently, and beautifully? These are lessons Blacksmiths feel in their bones and it’s well worth exploring the field yourself to appreciate the knowledge base that exists at any well-used forge.
I had an unexpected experience a few days ago at the Hacker Hotel weekend hacker camp in the Netherlands. At the side of the hotel our friends at RevSpace in The Hague had set up a portable forge. There was the evocative coal fire smell of burning coke from the hearth, an anvil, and the sound of hammering. This is intensely familiar to me, because I grew up around it. He may be retired now, but my dad is a blacksmith whose work lay mostly in high-end architectural ironwork.
The trouble is, despite all that upbringing, I don’t consider myself to be a blacksmith. Sure, I am very familiar with forge work and can bash metal with the best of them, but I know blacksmiths. I can’t do everything my dad could, and there are people we’d encounter who are artists with metal. They can bend and shape it to their will in the way I can mould words or casually solder a tiny surface-mount component, and produce beautiful things in doing so. My enthusiastic metal-bashing may bear the mark of some experience at the anvil but I am not one of them.
It was a bit of a surprise then to see the RevSpace forge, and I found myself borrowing a blacksmith’s apron to protect my smart officewear and grabbing a bit of rebar. I set to and made a pretty simple standard of the dilletante blacksmith, a poker with a ring on one end. Hammer one end of the rebar down to a point, square off the other end for just over 3 times the diameter of the ring, then bend a right angle and form the ring on the pointy end of the anvil. Ten minutes or so of fun in the Dutch sunshine. Working a forge unexpectedly brought with it a bit of a revelation. I may not be a smith of a high standard, but I have a set of skills by virtue of my upbringing that I had to some extent ignored.
Where others might have put effort into learning them, they’re things I just know. It had perhaps never occurred to me that maybe all my friends in this community didn’t learn how to do this by hanging round the forge next to the house they grew up in. If I have this knowledge merely by virtue of my upbringing, perhaps I should share some of it in a series of articles for those in our community who’ve always fancied a go at a forge but have no idea where to start.
When designing parts on a screen, it’s very easy to type in a bunch of nice round numbers and watch everything slot together in perfect harmony. Unfortunately, the real world is not so kind. A 10mm shaft will not readily fit in a 10mm hole, and producing parts to perfect dimensions simply isn’t possible. This is where fits and tolerances come in, and [tarkka] have created a practical demonstration of this on Youtube.
Hole and shaft tolerances are important to ensure parts mate correctly and as intended. If a shaft is to fit into a hole easily and the dimensions aren’t critical, a clearance fit is called for. If assembly should be easy but the part is required to locate accurately, a running fit is called for. Alternatively, if the parts are intended to be pressed together permanently, an interference or force fit should be used.
The video covers the basics of fits and tolerances in an easy to understand way, with visual examples. The fits discussed are based in Imperial measurements, but the metric standard of hole and shaft tolerances (ISO 286-2) is also noted.
So, a little hard to choose a topic, but we asked Simon to talk a bit about his recent Enigma watches. He has managed to put an electronic emulation of the Enigma cypher machine from World War II into both a wristwatch and, more recently, a pocket watch. They’re both gorgeous builds that required a raft of skills to complete. We’ll start there and see where the conversation takes us!
Please join us for this Hack Chat, where we’ll discuss:
Where the fascination with Enigma came from;
Tools, techniques, and shop setup;
Melding multiple, disparate skill sets; and
What sorts of new projects might we see soon?
You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the All Things Enigma Hack Chat and we’ll put that in the queue for the Hack Chat discussion.
Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
For most of human industrial history, the blacksmith was the indispensable artisan. He could fashion almost anything needed, from a simple hand tool to a mechanism as complex as a rifle. Starting with the most basic materials, a hot forge, and a few tools that he invariably made himself, the blacksmith was a marvel of fabrication.
If you have any doubt how refined the blacksmith’s craft can be, feast your eyes on [Seth Gould]’s masterpiece of metalwork. Simply called “Coffer”, [Seth] spent two years crafting the strongbox from iron, steel, and brass. The beautifully filmed video below shows snippets of the making, but we could easily watch a feature-length film detailing every aspect of the build. The box is modeled after the strongboxes built for the rich between the 17th and 19th centuries, which tended to favor complex locking mechanisms that provided a measure of security by obfuscation. At the end of the video below, [Seth] goes through the steps needed to unlock the chest, each of which is filled with satisfying clicks and clunks as the mechanism progresses toward unlocking. The final reveal is stunning, and shows how much can be accomplished with a forge, some files, and a whole lot of talent.
If you’ve never explored the blacksmith’s art before, now’s the time. You can even get started easily at home; [Bil Herd] will show you how.
Where there’s a will, there’s a way. Similarly, where there’s a paying customer and a well stocked metalworking shop, there will also be a way. That’s about all the backstory you need to understand this latest creation from [Richard Day] of 42Fab. A customer asked him to build something that didn’t exist, and in a few hours he not only fabricated it from scratch but documented the whole thing for our viewing pleasure.
The object in question is a mount that would allow the customer to pull a “Burley Bee” kid trailer behind their electric scooter. The trailer is only meant for a bicycle, but the expected stresses of getting pulled around by a scooter seemed similar enough that [Richard] figured it should work. Especially since the ride height of the scooter lined up almost perfectly with the trailer’s tongue. The trick is, he wanted to avoid making permanent changes to either the scooter or the trailer.
On the scooter side, [Richard] came up with a clamp arrangement that would squeeze onto the frame. This gave him plenty of strength, without having to put any holes in the scooter. To create the clamp he took two pieces of 1/4″ x 2″ steel flat bar and welded 5/16″ nuts to them. By drilling the threads out of outer nuts they act as bushings, so cranking down on the bolts draws the two pieces together. To simplify the alignment, he welded the nuts to the bars while the bolts were threaded in, so he knew everything would be in place.
For the trailer side, he took another piece of flat steel and turned it into a “U” shape by cutting almost all the way through the back of it and then folding it over in his vice. A bead of metal was then laid in the cut with the welder to strengthen it back up. [Richard] used this opportunity to demonstrate the difference between pushing and pulling the torch while welding, which is an interesting tip to file away. A hole drilled through the two sides and a little grinding, and it’s ready to mount.
Between the two fabricated components is some flat stock welded at an eyed up angle. As [Richard] says in the video, the nice thing about these one-off projects is that you can basically design on the fly. Plus you can always use a hammer to make some final adjustments.
If you are in the habit of seeking out abandoned railways, you may have stood in the shadow of more than one Victorian iron bridge. Massive in construction, these structures have proved to be extremely robust, with many of them still in excellent condition even after years of neglect.
When you examine them closely, an immediate difference emerges between them and any modern counterparts, unlike almost all similar metalwork created today they contain no welded joints. Arc welders like reliable electrical supplies were many decades away when they were constructed, so instead they are held together with hundreds of massive rivets. They would have been prefabricated in sections and transported to the site, where they would have been assembled by a riveting gang with a portable forge.
So for an audience in 2018, what is a rivet? If you’ve immediately thought of a pop rivet then it shares the function of joining two sheets of material by pulling them tightly together, but differs completely in its construction. These rivets start life as pieces of steel bar formed into pins with one end formed into a mushroom-style dome, probably in a hot drop-forging process.
A rivet is heated to red-hot, then placed through pre-aligned holes in the sheets to be joined, and its straight end is hammered to a mushroom shape to match the domed end. The rivet then cools down and contracts, putting it under tension and drawing the two sheets together very tightly. Tightly enough in fact that it can form a seal against water or high-pressure steam, as shown by iron rivets being used in the construction of ships, or high-pressure boilers. How is this possible? Let’s take a look!