This Stainless Steel Knife Build Starts With Raw Iron Ore

Making knives at home has become a popular hobby, thanks partly to reality TV and the free time and idle hands afforded by lockdowns. Depending on how far you get into the hobby, builds can range from assembling and finishing a kit with pre-forged parts, to actual blacksmithing with a hammer and anvil. But pretty much every build includes steel from a commercial supplier.

Not this one. Rather than buy his metal from the usual sources, [Thoisoi]’s first stop was an iron mine in the Italian Alps, where he picked up a chunk of iron ore — magnetite, to be precise. Smelting one’s own iron from raw ore and alloying it into steel is generally not a backyard project thanks to the high temperatures needed, a problem [Thoisoi] solved with the magic of thermite. The iron oxide and aluminum in the thermite mix react in an exceptionally exothermic manner to generate elemental iron, which under controlled conditions can be captured as a more or less pure ingot, ready for forging.

After a test with commercially obtained iron oxide, [Thoisoi] tried his pulverized magnetite. And thanks to the addition of goodies like graphite, manganese, nickel, silicon, and chromium, he was eventually able to create a sizable lump of 402 stainless steel. He turned the metal over to an actual blacksmith for rough forging; it sure seemed to act like steel on the anvil. The finished knife looks good and performs well, and the blade has the characteristic look of stainless. Not a bad result, and all at the cost of a couple of clay flowerpots.

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Super Magnesium: Lighter Than Aluminum, Cheaper Than Carbon Fiber

We think of high tech materials as the purview of the space program, or of high-performance aircraft. But there are other niche applications that foster super materials, for example the world of cycling. Magnesium is one such material as it is strong and light, but it has the annoying property of burning in its pure state. Alloys of magnesium meanwhile generally don’t combust unless they are ground fine or exposed to high temperatures. Allite is introducing a new line known as “super magnesium” which is in reality three distinct alloys that they claim are 30% lighter than aluminum, as well as stronger and stiffer than the equivalent mass of that metal. They also claim the material will melt at 1200F instead of burning. To lend an air of mystique, this material was once only available for defense applications but now is open to everyone.

It’s a material that comes in three grades. AE81 is optimized for welding, ZE62 is better suited for forging, while WE54 is made for casting processes. Those names might sound like made up stock numbers, but they aren’t, as magnesium allows typically have names that indicate the material used to mix with the magnesium. A stands for aluminum, Z is for zirconium zinc, W is for yttrium, and E stands for rare earths. So AE81 is a mix of magnesium, aluminum, and some rare earth material. The numbers indicate the approximate amount of each addition, so AE81 is 8% aluminum and 1% rare earth.

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Casting Tour-De-Force Results In Swashplate For Scale Helicopter

While quadcopters seem to attract all the attention of the moment, spare some love for the rotary-wing aircraft that started it all: the helicopter. Quads may abstract away most of the aerodynamic problems faced by other rotorcraft systems through using software, but the helicopter has to solve those problems mechanically. And they are non-trivial problems, since the pitch of the rotors blades has to be controlled while the whole rotor disk is tilted relative to its axis.

The device that makes this possible is the swashplate, and its engineering is not for the faint of heart. And yet [MonkeyMonkeey] chose not only to build a swashplate from scratch for a high school project, but since the parts were to be cast from aluminum, he had to teach himself the art of metal casting from the ground up. That includes building at least three separate furnaces, one of which was an electric arc furnace based on an arc welder with carbon fiber rods for electrodes (spoiler alert: bad choice). The learning curves were plentiful and steep, including getting the right sand mix for mold making and metallurgy by trial and error.

With some machining help from his school, [MonkeyMonkeey] finally came up with a good design, and we can’t wait to see what the rest of the ‘copter looks like. As he gets there, we’d say he might want to take a look at this series of videos explaining the physics of helicopter flight, but we suspect he’s well-informed on that topic already.

[via r/DIY]

What The Flux: How Does Solder Work Anyway?

I’ve been soldering for a long time, and I take pride in my abilities. I won’t say that I’m the best solder-slinger around, but I’m pretty good at this essential shop skill — at least for through-hole and “traditional” soldering; I haven’t had much practice at SMD stuff yet. I’m confident that I could make a good, strong, stable joint that’s both electrically and mechanically sound in just about any kind of wire or conductor.

But like some many of us, I learned soldering as a practical skill; put solder and iron together, observe results, repeat the stuff that works and avoid the stuff that doesn’t. Seems like adding a little inside information might help me improve my skills, so I set about learning what’s going on mechanically and chemically inside a solder joint.

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