Fetching Etchings for Stainless Steel

What do you do when you have a 10-gallon brew kettle (or any other stainless steel or aluminium thing) with no volume markings (or Hack a Day logos)? If you’re [Itsgus], you use science to etch some markings with a few household items and a 9V and you call it a day.

[Itsgus] used 1/4c vinegar and 1/4tsp of salt to form an electro-etchant and applied it with a Q-tip connected to the negative terminal of a 9V. He used tape to connect a wire between the positive terminal and the kettle. The vinegar dissolves the salt, creating negatively charged ions. Connected correctly to a 9V, the process removes metal where the current flows. If you were to connect it in reverse,  you would add a small amount of metal.

The process only takes a few seconds. When the etchant starts to sizzle and bubble, Bob’s your uncle. Even though the stainless steel’s natural coat re-oxidizes over the etches, you should probably wash that thing before you brew. If you prefer adding metal to removing it, try electroplating copper on the cheap.

Copper kettle just for the hipster coffee scene


Handmade coffee is a feature we need to write. But for now we present this copper kettle which is designed to pour out the boiling water very slowly in order to achieve the perfect cup of slow-drip java.

[CHS] made the kettle for his friend [Nate]. The entire process starts off with an arc of flat copper sheet which makes a slightly conical cylinder when curved until the two ends meet. Getting a water tight seal on this seam is imperative and it took four or five tries to reach perfection.

To get the kettle in shape [CHS] improvised a mandrel out of a thin slice of railroad track. After polishing it smooth it goes on the inside of the copper and gives him something to hammer against. We think this step is magic… It’s kind of like the old sculpting adage that you remove everything that isn’t what you’re trying to end up with. The beauty of the piece really pops out as the final curves are hammered into the work.

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Double-kettle boiling rig for and easier brew day

[Dave] built a controller that lets him boil two kettles at once when brewing beer. The setup uses electric heating elements in each of the kettles. We prefer to use gas as it’s a bit easier to control temperature. But an electric system like this can be used inside during the winter months while propane is relegated to the outdoors. The other thing that immediately comes to mind is partial mash recipes that require steeping in one kettle, then sparging (rinsing off the grains) with water of a different temperature. That kind of thing is a snap since the two are controlled individually by the trimpots on the front of the control box.

Inside you’ll find two 220V solid state relays. The box itself plugs into the 220V outlet in his basement which is normally occupied by his clothes dryer cord. So as not to blow a fuse, the MSP430 chip driving the relays switches back and forth between them rather than turning both on at once. The system uses entirely manual control, but it should be an easy modification to add a thermocouple and PID algorithms if so desired.

After the break [Dave] shows off the system in a video clip.

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Pulse jet tea kettle

[Colin Furze] is just showing off in this picture. His pulse jet tea kettle is built well enough to get by without help from a blow torch, but who can blame his showmanship? In fact, once it’s running there’s no flame to be seen. That’s because the combustion happens at an earlier stage of that pipe, heating a segment that is submerged in water so that you may have your tea in no time.

Once this thing is tuned up it roars like a robotic lion. [Colin] yells his commentary at the camera, but it is picked up as nothing more than a blip of distortion. Pressurized propane and air both feed into the jet. they’re regulated by the two knobs on the base of the unit (that enclosure is actually just a pie tin). There is also a 9V battery-powered igniter built into the base. You can see how the unit was built in the video after the break.

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Steam fife

This auto-flute does it with steam. Well, electricity gets its piece of the action too as the tone holes are opened and closed using a set of solenoids.

We’re at a loss on how the sound is actually produced. We would think that a penny whistle has been used here, except if that were the case the solenoid nearest the kettle would have no use. Then again, after watching the demo after the break we’re not sure that it does have much of an effect. It may be meant to stop the sound but it doesn’t really work all that well.

At any rate we’d love to see some spin-off hacks. Assuming the plastic can stand up to the steam heat this would be a perfect robot controller for recorder controlled snake. You can get a recorder for a buck at the right dollar store, and solenoids can be made out of simple materials. If you know of a way to produce the sound yourself, all it takes are a few careful calculations to place the tone holes.

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