Hack a Bike Electroetching

[Melka] wanted a track bike, but never quite got around to buying a nice one. Then he found an inexpensive abandoned project bike for 10 Euro. He had to do a lot of work to make it serviceable and he detailed it all in a forum post. What caught our eye, though, was his technique for electroetching.

The process is simple, but [Melka] says the procedure caused hydrochloric acid fumes as a byproduct. Your lungs don’t like HCl fumes. Apart from the danger, you probably have everything you need. He used electrical tape to create a stencil on the metal (although he mentioned that Kapton tape might come off better afterward) and a saturated solution of common table salt as the electrolyte.

Power comes from a bench power supply set to about 24V. The positive lead was connected to the metal and the ground to the sponge. From the photos, it looks like the particular piece and solution caused about 600mA to flow. After 10 minutes, the metal etched out to about 0.2 mm. After the etching, [Melka] brazed some brass into the etched area to make an interesting looking logo.

If you have a laser cutter, you can skip the chemicals. We’ve even seen laser etching combine with a 3D printer to produce PCBs. [Melka’s] method is a little messier and probably would not do fine lines readily, but if you need to etch steel and you don’t mind the fumes, it should be simple to try.

Propane Tanks Transformed Into Extreme Sandblaster

The [Make It Extreme] team has been racking up the builds lately, and a lot of them are heavy with metalworking. When you’re doing that kind of work, and you put as much care into finishing your builds like they do, it’s a good idea to have access to a sandblaster. So naturally, they built a really nice one.

We’ve featured a couple of [Michalis Mavros] and team’s build recently; you’ll no doubt recall this viciously effective looking spot welder and a sketchy angle grinder cum belt sander. The sandblaster build, centered as it is around scrap propane tanks, has some lethal potential, but luckily the team displaced any remaining gas from the tanks with water before doing any cutting. The design allows for a lot of sand in the tanks, with plans to provide a recycling system for the grit, which is a nice touch. And it works great – they even used it to clean it up before final finishing in the trademark [Make It Extreme] green and black paint job.

What we really like about the video, though, is that it’s a high-speed lesson on metalworking techniques. There’s a ton to learn here about all the little tricks needed to bring a large-scale metalworking project to fruition. It also demonstrates that we really, truly need a plasma cutter and a metalworking lathe.

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Designing a 360 Degree All Metal Hinge

Looking for a 360 degree hinge that had no slop was harder than [Mr. LeMieux] thought it would be. Add to the fact it had to be made completely out of metal with no plastic components — and basically fireproof. He was coming up blank.

You see, [Mr. LeMieux] is casting metal components, and needed a hinge to close two halves of a mold. When he couldn’t find anything commercially available, he decided to design his own. Using aluminum, he machined the two halves with an interlocking mechanism between the two. Essentially, it’s a 3-bar linkage, but if he stopped there, it would have too much slop. So he actually designed in two fixed gears that roll over each other — this ensures the hinge stays perfectly smooth throughout its entire range of movement — it’s actually quite ingenious.

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Building a Taller Drillpress

[BF38] bought a mid-range miniature drill-press, and discovered that it was just too short for some of his applications. “No problem,” he thought, “I’ll just measure the column and swap it out for a longer one.” It sounds foolproof on paper.

He discovered, after having bought a new 48.3 mm steel column, that the original was 48 mm exactly in diameter. He’d have to make it fit. But how do you bore out a 48 mm diameter hole, keeping it perfectly round, and only increase the diameter by 0.3 mm? A file is out because you’d never get it round. A lathe is out because [BF38] doesn’t have a lathe.

[BF38] ended up making a DIY honing head, which is a gadget that presses (in this case) two pieces of sandpaper evenly against the sides of the hole to be widened. The head in question is a little bit rough — it was made as a learning project, but it looks like it served the purpose admirably.

Retrotechtacular: Blacksmithing To The Stars!

When most of us think of forge work, the image that comes to our mind is likely to be a rather traditional one, of the village blacksmith’s shop, roaring coke-fired hearths, and an anvil ringing to the beat of hand-wielded hammers. Iron and steel, worked through the sweat of the human brow.

Precision metalwork probably doesn’t figure in there, yet there is another type of forging used to create some of the most highly stressed components on rockets, missiles, and aircraft as well as the more mundane ironwork of your garden fence. Drop forging allows reproducible shapes to be forged while maintaining tight control over the metallurgical properties of the finished product, exactly what is required for such high-performance applications.

The video below is a promotional film about drop forging in the aeronautical industry from the late 1950s, made for and about Wyman Gordon, still specialists in the field. With the charming optimism of the period and a very catchy title it goes into the detail of the plant, development, and quality control of a range of parts for the missiles and rockets of the day, and along the way shows the cutting edge of machine tooling in the days before CNC. A whole Periodic Table of metals are forged with an expertise probably not seen in many other places in the world.

There are also some sights you’d never see in today’s safety culture, for example a running press with men darting in to adjust the position of a forging while it is still moving. It’s not a short video, but definitely worth watching all the way through.

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Laser Removes Rust Like Magic

If you’ve worked with steel or iron, you will be very familiar with rust. You will have an impressive armoury of wire brushes and chemicals to deal with it, and your sandblasting guy is probably in your speed-dial list.

We’ve had more than one Hackaday reader contact us of late with videos showing an apparently miraculous handheld laser unit effortlessly stripping away rust, and leaving a near-perfect surface with little mess. Can it be real, they ask, is it an internet hoax? After all if you have done battle with the dreaded iron oxide you’ll know there is no miracle fix to the problem, however you deal with it there has traditionally been hard work involved.

So after a bit of research, we find CleanLaser, the German company whose products feature in the videos. Quoting their website: “Powerful, very short, rapid and moving laser pulses produce micro-plasma bursts, shockwaves and thermal pressure resulting in sublimation and ejection of the target material”. So yes, it seems they’re real.

The website is at pains to stress the environmental benefits of the devices over comparable sandblasting or similar technologies, but has very little information on their safety. They are available in power ratings from 12W to 1KW which is a hell of a lot of laser power to be projecting, yet the operators seem only to be wearing goggles. Perhaps this comes back to the “Powerful, very short, rapid and moving” bit in the quote above, is there no point source to sear your retina? Laser experts please enlighten us in the comments.

If you work with metal or grew up in a metalworking business, this machine probably has you salivating. Sadly for hackers and makers though it’s probable that it and ones like it will be out of our price range for quite some time. Still, the prospect of a guy with one in an industrial unit appearing in most towns can’t be too far away, and that can only be a good thing

The video shows the machine in action. Rusty fire-grate in, perfect shiny surface out. Perhaps only those of you who have spent many hours with a wire brush will understand.

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Cake Knife Tessellates Cake

Rectangles? Squares? Pie slices? Who says dessert has to come in that shape? Why not triangles, circles, or even hexagons? Master of all things woodworking [Matthias Wandel] decided to solve this problem, and delved into a bit of metal working.

Using a strip of 26 gauge stainless steel, [Matthias] threw together some wood clamps in order to bend the metal into funky looking blade. He then put slits into a nice wooden handle and assembled the whole thing with a very slight positive curve, allowing you to roll the knife as you cut your confectionery.

As you can see in the following video, it works pretty well — and always, it’s a pleasure to see this man work.

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