Make: Projects

Flashback: The Florence Siphon Arabica Brewing & Extraction Apparatus

I thought I was really into coffee until I met John Edgar Park, host of Make: television, contributing writer to Make: Online, and author of several MAKE magazine articles. John takes his coffee seriously. Seriously. Case in point was when he devised and wrote a how-to for his Florence Siphon Brewing and Extraction Apparatus for MAKE Volume 17, our Lost Knowledge issue. This apparatus is sure to raise eyebrows (and spirits) next time you invite someone to your workshop for a cup of blessed joe. Check out the whole project in this week's Flashback, and pick up a back issue of MAKE 17 over in the Maker Shed.

Make your own mad-scientist coffee machine.
By J. Edgar Park II

Aboard the dirigible Aeroship Phaedrus, two men are seated at a table in the onboard Laboratory:

"Doctor Liepold, would you kindly prescribe something to lift my depressed spirits?"
"Why of course, Captain Heffernan. What is it that ails you?"
"My mind feels sluggish and there is still much work to be done before daylight. I am drawing up charts for the expedition."
"Ah, yes, I have just the thing. Sit a moment while I extract the invigorants from these wondrous beans."
"Very good, thank you. What is that strange device, Herr Doktor?"
"I call it the Florence Siphon. It is an arabica brewing and extraction apparatus. Allow me to demonstrate. First, I fill this boiling flask with a quantity of pure spring water. It is a vessel of my own devising that can withstand great heat and pressure. I heat the flask, which causes the water to vaporize, passing through this tube here, through a filter, and into the beaker to my left. Here, the water commingles with precisely roasted and ground fruit of Coffea arabica. I give the slurry a rapid stirring to fully saturate the grounds, then wait.
"As my boiling flask cools, a vacuum is created, causing the very atmosphere of the Earth to push the liquid through the filter, leaving the grounds and all unsavory particulate matter behind. Thus the liquid, now filled with essences, oils, solubles, flavors, and vital invigorants, is returned to the flask. Allow me to unstopper it and pour you a dose."
"Doctor! You have outdone yourself! I feel revitalized by this most miraculous potion."

The vacuum siphon coffee brewing method dates back to the 1840s. It produces some of the cleanest, smoothest-tasting coffee of any method. Commercial vacuum pots are available, but I wanted to heighten the drama of vacuum brewing by taking it into the realm of the mad scientist's lab. Thus the Florence Siphon was born!

After studying original patent drawings and existing devices, I identified these key features:
• Water is heated in a boiling flask that has a tube leading to a second vessel containing ground coffee.
• The tube must have a filter, to allow the water to flow through but not the grounds.
• The filter must be submerged during brewing, so as to maintain a seal with the boiling flask.
• The second vessel must be accessible for stirring the slurry.
• The boiling flask must be large enough to create a sufficient vacuum as it cools to "pull" the coffee back through.

One drawback to early vacuum brewers was the constant danger of exploding glass. Today, we have plenty of high-quality borosilicate glassware that's up to the task — it just happens to be found in the lab, not the kitchen.

Filtration was another challenge. I tinkered with a few options (including an unfortunate foray into shower heads) before arriving at an inverted thistle tube. This is a type of bulbed funnel that's easy to cover with filter cloth. (Thanks to Dr. Jim Callan from Avogadro's Lab Supply for this suggestion.)

I assembled my funnel, stopper, tubing, filter, and a beaker for the grounds. I filled my flask with preheated water (small burners can take a while to boil 500ml), poured 38g of medium-ground coffee into the beaker, donned my goggles, and lit the burner.

The water began to bubble quickly, and soon went straight up the glass tube and over to the grounds. After about a minute, the flask was nearly empty and I extinguished the flame. At this point, there was an abundance of expanded water vapor (steam) inside the flask, which prevented the water from returning.

I stirred up the slurry with a stick and then waited with great excitement. Would the siphon be able to draw the coffee back up? At just about the 2-minute mark, I saw the gorgeous brown liquid begin its ascent. This is due to the vacuum created by the cooling and contraction of water vapor in the boiling flask. It was tentative at first, but as the boiling flask continued to cool, the coffee started to move quickly up the tube, over and then back down to the flask below. Within another 20 seconds, the journey was complete: 420ml of coffee made it back, leaving 80ml of water behind with the grounds.

I removed the stopper and poured myself a cup. It was perfect! Smooth, bright, clear, and clean. Vacuum coffee is a step above a French press, and leagues above drip. Plus, when you brew with the Florence Siphon you get to don your lab coat and cackle maniacally. What more could you want from a cup of coffee?

Here's how to build your own Florence Siphon.

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Posted by Goli Mohammadi | Feb 3, 2010 06:00 PM
Chemistry, MAKE Projects | Permalink | Comments (5) | Suggest a Site

Make: Projects - Periodic table elements collection cabinet

Every chemist (and arguably every scientist, and arguably everyone else in the world), whether amateur or professional, should have an elements collection. Theodore Gray has written eloquently about the hows and wherefores of collecting the chemical elements, so I won't belabor the point here other than to say: chemistry has been called the central science, and arguably, chemistry's greatest achievement has been the discovery of the chemical elements, the realization of the periodicity of their properties and its implications for atomic structure, and the isolation of each of those elements in its pure or "standard" state. Collecting the individual elements lets you participate in that incredible story in a way that no amount of book-learnin' ever will.

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Posted by Sean Michael Ragan | Jan 24, 2010 07:00 PM
Chemistry, MAKE Projects, Science | Permalink | Comments (2) | Suggest a Site

Make: Projects - 15-minute ice cream with a dry ice bath

Photos by Maya Chavez-Akin.

Making ice cream with cryogens stronger than water ice is a fairly common chemistry demonstration stunt. The ideal way to do it is with liquid nitrogen, which is poured directly into the ice cream mixture, with stirring, and causes it to set up in about 10 minutes. Liquid nitrogen, however, can be rather difficult to get your hands on. Most major cities have a supplier that will sell it to you, but very often they have large minimum orders and/or require that you own an expensive dewar flask into which they may safely dispense the liquid nitrogen. At -196 C, liquid nitrogen is also fairly dangerous to handle.

Dry ice is a much more accessible cryogen; it's available at several major grocery stores in the Austin area, for instance, and I imagine the same is true in other parts of the United States. It sublimes at -78 C, and is thus vastly more effective at freezing stuff than water ice at 0 C. You can make ice cream, just as with liquid nitrogen, by adding dry ice directly to the ice cream mixture. However, because dry ice is frozen carbon dioxide, this procedure results in carbonated ice cream. Which can be quite delicious. But say you don't want carbonated ice cream?

This procedure borrows from a common technique in the organic chemistry laboratory for cooling reactions to sub-zero temperatures. Instead of using ice water to cool to 0 C, you make a bath of dry ice in some volatile solvent that will not freeze at dry ice's sublimation temperature of -78 C. Obviously, you can't use dry ice in water because the water will freeze solid. In the laboratory, acetone and isopropyl alcohol are common coolants. Acetone, however, can be dangerous if handled improperly, and isopropyl alcohol in sufficient quantities to make a large bath can be rather expensive.

I have discovered, however, that denatured ethanol, which is available in hardware stores everywhere, is reasonably priced and makes a good bath with dry ice. Denatured alcohol is also much safer to handle than acetone. Depending on the denaturant, it is also the least toxic of the various hardware-store solvents. In any case, done with reasonable care, this procedure involves no significant risk of contact between the ice cream itself and the coolant. And although denatured alcohol is quite flammable, the dry ice temperature of -78 C is well below its flash point at 13 C, which means that, once the bath is cool, there is no danger of the alcohol vapor igniting from a stray spark. To err on the safe side, however, you should be sure to work in a well-ventilated area.

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Posted by Sean Michael Ragan | Jan 16, 2010 07:00 PM
Chemistry, MAKE Projects, Science | Permalink | Comments (19) | Suggest a Site

Intern's Corner: Makey robot's sonar and maiden voyage

MAKE: Intern's Corner
Every other week, MAKE's awesome interns tell about the projects they're building in the Make: Labs, the trouble they've gotten into, and what they'll make next.

By Kris Magri, engineering intern

How I designed Makey, Part III: The Ping sonar rangefinder and maiden voyage

As we return to our robot design saga, making Makey the Robot for MAKE, Volume 19 ...

The actual robot is still just a prototype with 2 wheels and motors and no sensors, electronics, or brains inside. The better body exists only in the computer. Maker Faire is looming. I've been tapped to give two "Make Your Own Robot" workshops, and I reckon that having a working robot would be a very good idea.

I'm trying to get the Arduino into the robot body. Suddenly I learn a profound lesson regarding computer-aided design. In real life, circuit boards cannot morph through walls into their desired resting place. In the computer, it happens all the time. With a simple motion of the mouse, the Arduino circuit board has glided into place, right through the aluminum robot body ... but in real life, it won't fit. There is no possible angle or tilt that will get the Arduino into the robot. Out come the Vise-Grips and hacksaw. I saw, bend, and twist off the offending aluminum tabs. This is reality-aided design.

The battery pack doesn't fit because it hits the nuts and bolts that hold the motors in. It fit just fine in the computer model, since I didn't bother including the nuts and bolts. I'm ready to toss the computer out the window.

I show up at the Make: Labs with my fail robot. Our crew has been working like demons for weeks getting ready for Maker Faire -- preparing demos, packing everything under the sun, buying materials -- the lab is a madhouse. Eric, myself, and Steven are practically tripping over each other. I'm frantic to get the Arduino into the body and get the sonar sensor mounted somehow. Eric suggests double-stick tape. I refuse. Tape and glue, I assert, are for people who don't know about bolts and rivets. Eric manages to cram the Arduino in sideways. It barely fits, actually, it doesn't quite fit, it sticks up a little. When I drill a mounting hole, 1/3 of the hole isn't there. But the bolt manages to hold.

At this point I only have a vague idea of what motor will be turning Makey's "eyes" or how to fit it inside. We zoom off to the local hobby shop and pay way too much for the smallest servomotor they have in stock.

Steven offers to take on the servomotor/sonar sensor mounting problem. He's making detailed measurements and calculations, trying to figure out how much space there is and where the servomotor will fit into this 3D space without hitting the electronics. He marks everything and explains his calculations to me. I can't follow them, but it sounds good and looks like it might just fit. I drill the holes, we put the servo in, then close up the robot. It fits! There is much rejoicing.

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From MAKE magazine:
make volume 19 cover.gif

In MAKE, Volume 19: Robots, Rovers, and Drones, learn how to make a model plane with an autopilot and a built-in robot brain. We'll also show you how to make a comfortable chair and footstool out of a single sheet of plywood, a bicyclist's vest that shows how fast you're going, and projects that introduce you to servomotors. All this, and lots more, in MAKE, Volume 19! Subscribe here. Buy the issue in the Maker Shed.

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Posted by Keith Hammond | Jan 13, 2010 09:33 AM
Arduino, Intern's Corner, MAKE Projects, Open source hardware, Robotics | Permalink | Comments (0) | Suggest a Site

CupCake CNC build, part 7: Building the Y-stage and adjusting the Z-stage

Before we go ahead and make the Y-stage, lets go ahead and level the Z-stage. It's a really easy process. All you need to do is adjust the nuts on the Z-stage threaded rods until they are all the same height. You did add an extra nut on each of the threaded rod, didn't you? I used a mechanical pencil as a reference point, but you can use anything, just get them all at the same height. Note: It's always best to get a second opinion, be it human or feline.

Now it's time to build the Y-stage. This only takes about 30 minutes and goes together fairly easily. One thing to note, some of the parts are laser etched on the wrong side. Take a close look at the pictures and make sure everything is going together the proper way. Apparently this is only an issue with CupCake CNC machines from batches 6-9.

Let's start by assembling the build platform. My kit came with a few extra, which is a good thing since the one in the picture doesn't work! The build platforms need to have (3) holes in the top to accommodate the (3) screws that are on the Y-stage assembly. I guess they redesigned the Y-stage and forgot to change the build platform. Oops! However, I received (2) additional build platforms in the kit, and both of them have the (3) holes allowing them to sit flush with the Y-stage. Problem solved!