Retrotechtacular: The Bessemer Converter

Here’s a rose-colored look into the steelworks at Workington, Cumbria in northern England. At the time of filming in 1974, this plant had been manufacturing steel nonstop for 102 years using the Bessemer process. [Sir Henry Bessemer]’s method for turning pig iron into steel was a great boon to industry because it made production faster and more cost-effective.

hot ingotsMore importantly, [Bessemer]’s process resulted in steel that was ten times stronger than that made with the crucible-steel method. Basically, oxygen is blown through molten iron to burn out the impurities. The silicon and manganese burn first, adding more heat on top of what the oxygen brings. As the temperature rises to 1600°C, the converter gently rocks back and forth. From its mouth come showers of sparks and a flame that burns with an “eye-searing intensity”. Once the blow stage is complete, the steel is poured into ingot molds. The average ingot weighs four tons, although the largest mold holds six tons. The ingots are kept warm until they are made into rail.

The foreman explains that Workington Works would soon be switching over to a more modern process. As it was, Workington ran a pair of Bessemer converters on a 40-minute schedule, ensuring constant steel production from ore to rail. Between 1872 and 1974, these converters created an estimated 25 million metric tons of steel.

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Iron casting in the parking lot

Here’s one good thing about the bitter cold Midwestern winter, it helps keep you from overheating when working around a hot furnace. Back in February this iron pour happened in the parking lot of the Madison, Wisconsin based Sector67 Hackerspace. Look, they’re making iron hearts!

Now this isn’t just a bunch of members who got together and decided to do some casting. As you can tell in the video after the break the team knows what they’re doing. The event was a collaboration with FeLion Studios, a custom cast-iron art boutique. But the Hackerspace participants did get to take part in the process of building the cast, watching the pour, and cleaning up the rough results.

One of the people from FeLion Studios just appeared on the Martha Stuart Show, along with a 550 pound cast-iron frying pan United States map.  [Chris] from Sector67 tells us the New York frying pan that [Martha] is hold was a product of the parking lot pour.

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Halloween prop: DIY fog machine

diy-fog-machine

Reader [Daniel] told us about a video detailing how to make your own fog machine. This project uses two disposable roasting pans to create a fog chamber. Inside you will find an upside-down clothes iron to convert fog liquid into a gas. The liquid is gravity-fed from a water-bottle reservoir on top, converted to smoke by the hot iron, then the newly created smoke is directed out of the chamber by a 12 volt fan.

You probably have an old iron sitting around (especially if you use the toner transfer method for making PCBs), as well as a fan of some type. The build method used in the video is not at the level we usually look for. Using one blade of a pair of scissors is not what we recommend for stripping wire insulation. We also don’t advocate hot gluing a wire to a battery for a reliable connection (for that you’d want wire glue). But with better building techniques, and perhaps an air intake fan for better fog direction, this has potential.

The project is predicated on the availability of “fog juice”. We’re probably not going to head out and buy a bottle of that so look into making some yourself from glycerin and demineralized water.

PCB toner transfer with dowel

dowel

Pulsar Professional FX has a neat tip on their site for getting a really even toner transfer when making your own PCBs. First, the PCB is cut to size, and the paper is tacked to the board. Then, the PCB is placed paper up onto a dowel and rolled back and forth with the iron. Since the board bends slightly over the dowel the toner sticks evenly to the copper. After that, just remove the paper as usual and etch with your preferred method.