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Archive: MAKE Projects

November 6, 2009

How-To: Make a Star Trek Bluetooth Communicator

Usually I write about ham radio. But looking at communication devices of the future from the past, I thought it would be fun to have a Star Trek: The Original Series Bluetooth communicator for a cellphone. I worked with Dave Clausen to hack one together from a toy Star Trek communicator, a Bluetooth module, and a microcontroller. Following are the directions and program to make your own. And of course a video to show how the Star Trek Bluetooth Communicator works.

And if you really want to geek it up, the Star Trek Bluetooth Communicator can also be used with the Yaesu VX-8R ham radio. It also makes an awesome gift. Read on for the full tutorial.

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CupCake CNC build part 1: Introduction & background

Having just arrived home from a quick trip to the hardware store, I was pleasantly surprised to see a large, unmarked, cardboard box sitting on my front steps. This isn't an uncommon event, since I am constantly checking out cool products and projects for the Maker Shed, however this box was a bit larger than normal.

Oh wow, it's the CupCake CNC kit from MakerBot Industries! I'd ordered it weeks earlier and had completely forgotten about it. (The truth is out: I have an atrocious memory, sad but true.)

And so the adventure begins! I'm going to document my "out of box experience" with a MakerBot. How many posts will the series be? I'm not sure since I've never built one. How often will I post about the build? Again, not sure, but I'll try to do at least one a week, maybe more, it all depends on how much free time I have between all my other maker-ly projects.

A little background: My CNC experiences

I've been tinkering with CNC for about 10 years, and consider myself an enthusiast, not an expert. I do own a few CNC mills, routers, and lathes. I have retrofitted old mills, and even build one from scratch. Pictured above is my mobile CNC machine, dubbed the "MobileC." I stuffed all the components into a mobile tool cart so I could bring it to hackerspaces, workshops, and events, all in the hopes of helping out fellow makers.

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November 4, 2009

Intern's Corner: Making Makey's "stretchy" body in Inventor

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 II: Creating the "stretchy" robot body in Inventor

When designing Makey the Robot for MAKE, Volume 19, I ran into a problem that plagues all kinds of designers -- how to continually redesign a body to accommodate changes in whatever's crammed inside it?

Once I'd sketched out Makey's configuration and modeled the major parts in Autodesk Inventor 3D modeling software, I really got into some of Inventor's awesome features. Inventor has three basic design types you work with: sketches, parts, and assemblies. Up to this point I had designed each individual component, including Makey's robot body, as a part, as shown in Figure A.

Fig. A: Makey's sheet metal body, near-final version, shown as a single part in Autodesk Inventor. Because I designed it as a component of an assembly, all the mounting holes and dropouts are perfectly aligned to internal robot components; if I move the components, Inventor automatically moves the holes.

Once I had these parts modeled, I placed them together into an assembly, as in Figure B. Then, I attempted to stretch the robot body as needed by making that part "Adaptive" inside the assembly. (That's what Inventor calls "stretchy" parts, and it's a powerful feature.)

Fig. B: Makey's body shown as part of an assembly in Inventor, constrained to the edges of the motors (at bottom, in blue). If I move the motors, the body automatically stretches to accommodate the new motor positions. Similarly, I constrained the battery boxes (at top, in tan) to the body, so wherever the body stretches, the battery boxes follow automatically. Nice!

Also, I cut holes into the body where I needed them for mounting the motors. This was the wrong approach! It seemed to work, but when I looked at the robot body as a part, outside of the assembly, the holes I had made weren't shown. They had simply vanished.

The reason for this is that Inventor can't know ahead of time how you're going to use a part. You could design one part that could be used in multiple assemblies, so if you alter the base part in any way inside one particular assembly, the alteration exists only in the assembly, but the base part is unchanged. Thus, my changes didn't "take hold."

The key was to create the robot body from inside the assembly. You can actually be inside an assembly and make a brand-new part. To do this, in the Assembly Panel area, instead of selecting Place Component, choose Create Component.

I ended up first creating what I called a "base plate," which existed solely to help me anchor all the parts, including the robot body. It would not be a part I would actually fabricate. I then placed the base plate, the motors, the Arduino, and the batteries into an assembly, using Place Component, and assembled it all by anchoring everything to the base plate (using constraints). This was pretty much what I had been doing before.

Now, still inside the assembly, I created a new part, via Create Component, which would become the robot body. I selected the material type Sheet Metal.ipt, since it's a sheet metal part, and created each bend and flange step by step, inside the assembly. This robot body now "belonged" to the assembly, and was adaptive inside the assembly. Any editing of it, from that point on, was always initiated from within the assembly.

Instead of making the body a specific width, I just made everything extra large with no dimensions. Once the body was formed, I finished editing, and now I was back inside the assembly with my new robot body. I then constrained the side of the body to an existing "edge" from another part, for instance, the sides of the motors (Figure B). When the constraint went into effect, the sides of the body "snapped" into place next to the motors. To make holes, I projected the motor mount holes onto the robot body, again edited the robot body part (from within the assembly), cut holes there, and then the holes "stayed put," so to speak.

Success at last -- I had modeled a fully adaptive robot body that I could easily modify to accommodate all the robot components I would be cramming inside it.

Next up: The battle to fit the brains inside.

More: How I designed Makey the robot, Part I: The first design

October 21, 2009

Intern's Corner: How I designed Makey the robot

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

Part I: The First Design

This summer I was given a once-in-a-lifetime opportunity to make a robot for the pages of MAKE Magazine (Volume 19, "My Robot, Makey"). As an intern, I had the inside scoop that an upcoming issue would focus on robotics. I talked with one of the editors, Goli Mohammadi, about including a step-by-step article showing people how to make their own autonomous robot from scratch, using an Arduino microcontroller. She took the idea to the rest of the crew, and they gave me a chance, asking for a draft article about the robot. I went into hyper-drive that weekend, designing and building a robot prototype in 44 hours over three days. This is a behind-the-scenes look at designing Makey.

The first thing I did was sketch ideas on paper. I based Makey on WALL-E, the little yellow robot hero from the movies. I quickly noticed that WALL-E's eyes are huge in contrast to his body. I knew the dimensions of the Parallax Ping sensor, which I planned to use for Makey's 'eyes,' so I realized I'd need to keep Makey's body as small as possible, to make the eyes look as big as possible.

I used Autodesk Inventor to design Makey. I can't say enough good things about this software. I've been using PCs for a good long while, and compared to big Unix workstations, I've never been impressed with what PCs can do for you. Inventor changed that. Inventor is the single best reason to own a PC, IMHO. I learned Inventor at school as part of my engineering curriculum, and this software is the "missing link" that has finally allowed me to design robots like I want to. Makey is the fifth robot I've built from scratch, and the first one I've designed on the computer, and the difference is like night and day.

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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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October 10, 2009

How-To: Time lapse movie from photos

Sometimes you want to tell a story that takes a while to unfold. One of the beauties of digital photography is that you are not limited by how many shots are on the roll of film, now you can shoot until your camera's card is full. With the high capacity cards available now, you can shoot a very large amount of high resolution photos and barely fill your card.

In this project, we'll use Windows Movie Maker, which comes bundled with the operating system on many computers. If you have a Mac or Ubuntu machine, keep looking. iMovie surely has a process similar to this, and I haven't found a good way to work with movies on Ubuntu. Add your thoughts in the comments if you know of good software for other other platforms. All the windows machines in my classroom run on XP, I have heard that Moviemaker is a bit harder to find in Vista.

Making movies and sharing them online is a great way for students to sum up what they have learned from doing a project. By using the video description, students have a place to park a written explanation of what the project helped them learn and what the photos depict. They can write the text in any word processor and then add it to the video description when it is uploaded. If they need to alter it later, they can just edit the notes by logging in and making the changes.

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October 9, 2009

Make: Projects - Pages of a forbidden tome

They could be from The Necronomicon, Unaussprechlichen Kulten, or simply Poe's "quaint and curious volume," but everybody needs at least a few tattered leaves of ancient mind-blasting arcanum lying around to impress guests. Especially around Halloween.

This tutorial presents an easy method for producing weathered "antiqued" paper with burned edges. The trick of soaking white paper in coffee or tea to give it an old, yellowed look is very familiar, but the process for selectively burning the edges of the paper is something I discovered on my own. A simple and safe chemical treatment is used to selectively char the page, only where it has been applied, upon mild heat treatment.

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October 3, 2009

Chutney jar PCB etch

I had two circuit boards nagging me to be etched this morning. Without a photo developing tray, it seemed some modifications in technique were in order. Into the recycling bin I went, looking for a smallish, wide-mouthed glass jar. Yesterday's sandwich polished off a tasty mango chutney, and the jar was just about right. A little bit of cleaning, and it was ready for business.

The leftover etchant from yesterday's vinyl PCB resist adventure was in a plastic bottle and still had some potency. The tea water was hot on the stove, so it was ready to provide some double-boiler action. I poured some hot water into a steel pan, put the ferric chloride into the jar in the pan, and dropped in the first board.

With a jar, you can tighten the lid and do more vigorous agitation than in a tray. Between the shaking and the heat, the process is quite a bit faster than when using a room temp bath and a pan. I forgot to check the time, but it was definitely quicker than yesterday. After the first of today's boards was cleared, I dropped in the second at 10 minutes to 11. This one I agitated even more than the first one, and it was easily done by 11. When it was clear, I rinsed off the boards and headed to the soldering iron.

After wiping down the boards with acetone to remove the adhesive from the vinyl sticker, I tinned the traces to get them ready for the chip, which will be soldered onto the PCB SMD-style.

This technique would be a lot simpler and safer to use with students in your maker classroom than agitating in open trays. Since the chemicals are sealed away inside the jar, there will be much less of a chance of spillage or splashing. Check out the PCB etching article in MAKE, Volume 02 for more ideas and techniques.

October 2, 2009

Make: Projects - Hot to cold smoker conversion

This is a simple kludge, really, but it's worked out remarkably well, considering I knocked it together in about 40 minutes 5 years ago and it's seen almost monthly use since then. What I started with was a pile of junk grill and smoker components, most of which came from a Brinkmann "Gourmet" smoker (as shown below) that my mother once accidentally set on fire. Lots of electric smokers have this three-part lid/body/base construction, however, and the exact make and model are not important.

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September 19, 2009

Make: Projects - "Pepakura-cast" metal pyramid puzzle

This project began when I read the following entry [#274] in Volume 1 of Popular Mechanic's 1913 The Boy Mechanic:

The round lead weight for shot-putting or hammer throwing can be cast in a hollow cardboard or pressed-paper ball, sold in department and toy stores for 10 cents. Cut a 1/2-in. hole in the ball as shown in Fig. 1 and place it with the hole up in damp sand and press or tamp the sand lightly around the ball as shown in the section, Fig. 2. Cover over about 1 in. deep. A wood plug inserted in the hole will prevent any sand falling inside. When the sand is tamped in and the plug removed, it leaves a gate for the metal. Pour melted lead into the gate until it is full, then, when cool, shake it out from the sand and remove the charred paper. A file can be used to remove any rough places. The dry paper ball prevents any sputtering of the hot lead.

This idea of a hollow card or paper form buried in plain sand as a sacrificial mold for poured metal parts interested me. As the internet papercraft explosion has taught us, paper is really not a bad medium for 3D design, especially for the cost. Software like Pepakura Designer will convert any 3D digital model into a papercraft one that can be printed out, cut out, folded up, and glued or taped together to make a reasonably accurate real-world replica of the original. What if, instead of using the paper as a positive representation, one were to use it simply as a negative space--a volume, supported by dry sand, that would survive just long enough to impart its form to molten metal poured inside?

As a first experiment, I designed a paper template for the pieces of a classic put-together puzzle often called "The Four Piece Pyramid." The challenge is to use the four identical pieces to form a symmetrical three-sided pyramid. I chose this prototype form, first, because I think the puzzle is elegant; second, because all four pieces are identical so only one template design is required; and third, because the pieces are fairly simple, geometrically, and thus so are the templates.

Tools

Computer with printer
Scissors or an art knife
Steel or aluminum bowl
Safety gear (see below)
Suitable heat source
Melting pot
Tongs or pliers for handing melting pot
Squirt bottle with water
Hacksaw frame with coarse blade

Materials

120 cm³ (1/2 cup) metal to melt (see below)
Play sand (or table salt)
The heaviest card stock you can get through your printer
Printer ink
Scotch tape

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September 9, 2009

Intern's Corner: The Make: Labs plastic bender

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

One of my favorite tools here at Make: Labs is the plastic bender. The coolest thing about it is using the variac, a giant heavy thing that truly adds some "mad science" cred to any workshop. You plug it in and crank the ginormous dial to vary the amount of AC voltage going through the heating element. How fun is that?

I followed the instructions in MAKE, Volume 10 (Project: Plastic Fantastic Desk Set), and made this spiffy tool holder for the lab.

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September 6, 2009

How-To: Classroom vibrobots

Vibrobots are an easy project for your maker classroom students and workshop participants. Relatively quickly, you can have people build their own small vehicle, construct a simple electric circuit and have the critter move around due to its' weighted motor. The materials are cheap or free, allowing you to encourage participants to take their creation home for further inspiration.

You may want to pair the vibrobot with the CD scrounging project. After scrapping the drives, you then have an excellent collection of parts perfectly suited for the vibrobot project.

Skills in this project:
Building electric circuits
Making a transportation vehicle
Working with the design process
Use of tools and supplies
Determining positive and negative voltage

Materials:
This project is so flexible that you can substitute for just about everything on this supply list. Really, look around at the junk you have and figure out a way to use up some of the debris on hand before spending your budget.
You can get all the parts you need from scavenging computer CD drives
Battery holder, you can buy them or have participants make their own
Motors
Wire and other conductors
Rigid materials for the body
Springs are nice for feet
Zip ties
Hot melt glue
Nuts/bolts/washers

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September 5, 2009

How-To: Program a person

When introducing kids to programming, it's helpful to get them into the mindset of programming. Having this experience will help them to get the concept that they are in charge of what the code does. They should also see that there is a lot of programmed behavior in the devices and systems in our lives.

Supplies:
People
Paper
Pens/pencils
A space to work in, tiled floors can be handy for calibrating moves

Tools
None

Concepts
Programming
Communications systems
Iterative or Design process

Time frame
This takes at least 20 minutes to explain and do. After that, you could use it as a filler activity, where you use it to illustrate a concept in the language that you are learning.

Mastery Objective
Students or participants will know how to create a very simple programming language so that they can command another person to perform simple tasks and explain where programming is present in other parts of their lives.

Process
Have participants get together in groups of twos or threes. Big groups don't work as well.
Each group will need a piece of paper and a pen or pencil
Each group creates their own code of simple commands.
Their commands will be written on the piece of paper and then spoken to the programmed person.
The programmed person should not have to read the code, it should be transmitted to that person verbally, or on slips of paper in a sequence.
The programmed person will then carry out the written code as accurately as possible.
Students and participants should use the iterative process, where they try their program and refine it as they go. If they don't test out the program, it may not do what they want, their may be miscommunications or sloppy code that the programmed person does not follow well.
Have each of the groups or pairs demonstrate to the rest of the group what they have programmed.
Each group in turn has a person who calls out the code, and another person who executes the code.
Each person should think of several objects or systems that use programming techniques in their daily life.

Keep it simple
Make a code of at least five lines of code, one command on each line.
They should avoid words like: "and," "next" and "then," which will have the effect of making commands more complex. Implied in the system is that the next line of code or simple command is "next" or "then."

Don't make it impossible
Keep the commands realistic for your situation.
If you are limited on time, they should not repeat movements or events dozens or hundreds of time.
If you are limited on space, they shouldn't have commands like "run for twenty seconds" or "jump eight feet"
If you have regular human beings, they shouldn't have commands like "jump up three feet" or "lift the maple table top"

Extensions
You could have them create a common syntax for their code, making it more consistent.
Create objects of groups of participants, that could all be commanded by one person acting as the transmitter of the code.

If you try this out, please let us know how it goes in the comments. Send in some photos and video to the MAKE Flickr pool and tag it with ProgramAPerson.

August 30, 2009

How-To: CD drive scavenging for parts

Old CD drives are a decent source for parts to make things from. Since the computer industry has encouraged manufacturing churn for so many decades, it is pretty easy to find at least a few surplus drives to dissect. Inside these dusty relics, you will be lucky to find DC motors, switches, gears, springs and more. The tools you will need are pretty easy to come by as well. From the parts you will find, you can make a number of interesting projects.

You can get drives from old computers, which always seem to be at the dump, on the sidewalk of some neighborhoods, out on the loading dock of the school, in basements and garages, etc. It is important that wherever you get them they come to you legitimately free of expectations. These will not be functioning drives after a few minutes of the project.

Teach your family to solder! Take a few pictures tagged as "MAKEcation" and put them in the MAKE Flickr pool by September 9th to enter to win a $100 Maker Shed gift certifiate!

Supplies:
Old computer CD drives (older ones often have better parts)
Plastic bags for storing parts (zippered half size sandwich bags are great)
Small cardboard boxes for storing the larger metal and plastic parts
Battery holder
Tape
Paper and pen
Digital camera
Paper clip

Tools:
Safety glasses
Small phillips head screwdriver
Straight screwdriver
Jeweler's screwdrivers
Pliers, needle nose or channel lock
Utility knife
Soldering iron
Wire cutters/strippers

Concepts:
How does it work?
How is it made?
Differences in technique and age of manufacture
Identifying electrical components
Getting and organizing supplies for future use

Time frame:
An hour or more is ideal

Mastery Objective:
Students and participants will know how to safely disassemble a CD drive or similar electrojunk for parts and project supplies so that they can name the parts inside the device, compare the varieties of manufacturing techniques to solve the same problem and organize the usable parts and components for future use in projects.

Process:
What do you have?
Probably the first thing to do is look at the exterior of the drives you have.
Make note of any markings on the drive. Some things you will likely find are the manufacturer, model number, read/write speed of the drive and my favorite: Date of Manufacture.
The date of manufacture will give you some context to judge the drives in your collection by. Often the older the drive is, the more "off the shelf" the components are.

Use your camera:
Take some photos with your camera or camera phone to show the process of taking the drive apart.
You can also have participants and students take pictures of each of the systems they find, and each of the types of components they find inside.

Case disassembly:
Put on your safety glasses.
Use a screwdriver to take the metal case off the drive. It will usually be 4 phillips screws on the sides that hold it together.
In taking off the metal case, try to keep it from getting deformed. The steel can be useful later. You may find that there are plastic tabs holding one of the pieces in place.
Try to get the case to just fall apart without having to be forced. Most of the time it will just come apart after you remove the screws and press on the plastic tabs.
If you do have to tug on the parts, you may have missed a screw under a sticker. If all else fails, make sure all of the eyes are protected, and pull it apart carefully, probably below the table.
Pop open the CD drawer by straightening out a paper clip and slipping it into the hole on the front panel. The drawer should open easily. You might even find a disc inside.
To remove the drawer, you may have to pry apart the plastic sides, or it might just come apart easily. Different models have varying designs. Be careful if you put force on it that the parts don't fly and hurt somebody.

Be careful not to Over-Disassemble!
You may find that there is a dc motor that is in a plastic housing that holds it in contact with a gear which could serve as a nice little drive wheel. Take it out, but secure it together so it can be used in a future project. If it doesn't stay together with screws or pressure fitting plastic, run a bit of tape around it to hold it.
You may also find that the CD reading eye moves nicely on its' slides. If it is controlled by a DC motor, this could be a neat system to use later.
Basically, look at the things you are taking apart, and see if they can be used as systems or components.
Securing the wires coming from the motor with a bit of tape will help keep them from breaking off later.

Motors and how to read them:
You should find two types of motors inside: DC motor and Stepper motor.

The easiest way to identify a DC motor is by looking at the number of wires coming off it. Most have just two wires. DC motors are controlled by sending electricity through the motor, causing it to turn either clockwise or counterclockwise. Sometimes you may find that there are several more wires going into another area of the case. These can be to an encoder that helps read the speed and direction of the motor.

Stepper motors have more wires coming from them, and often are built right onto a circuit board. These turn by receiving a series of pulses, each of which advances the motor one step. By controlling the timing and quantity of the pulses with a microcontroller, it is possible to precisely set the speed and even the number of degrees the motor will turn.

Save the good bits
As you go, put the useful parts into plastic bags or bins. Label the bags with scraps of paper for easy identification.
You should be able to find at least the following:

DC motors, usually one will open the tray, sometimes you will find a second to move the eye.
Gears to drive the mechanisms
Switches, either momentary pushbutton or other mechanical contactors
Headphone jack
Potentiometer
LED
Screws

Desolder the components you want from the circuit boards:
The headphone jack, LED, momentary switches and sometimes motors will be soldered directly to the circuit boards. You can use a desoldering braid and an iron to free these items from the boards. If they have fittings, you may want to keep the fittings and instead remove the headers that connect them to the board. You should be able to scrape the coating off the metal traces to solder the fittings to a wire for future projects.

Extensions:
Make a vibrobot.
Practice soldering and desoldering with the components on the boards.
Use a battery holder to power some of the things you find inside.
Use a fishing tackle box to store your parts in labeled bins.
Make a video explaining what you have found inside your CD drives.
Make a poster identifying each of the parts of a CD drive and telling what each does.
Use the parts of the drives to make something amazing!

So give it a shot!
You can try this solo, but it is definitely more fun scavenging old drives in a group with the stuff all ending up on the table. You can compare the differences and similarities between drives better in a group, and you can share observations about the systems. Having a nice collection of stuff to pick from is a great feature of the project. An added bonus is finding handwritten markings made by the people who made the drive. Give yourself and the group some time to explore what you find. In my experience, it takes a few hours to dig through the drives and then make something from the debris. You can do it in one workshop, or you can spread it over a few classes. Share your findings in the comments, and add your photos to the MAKE Flickr pool.

More:

August 29, 2009

How-To: Free DIY battery holders

In this project, we'll make battery packs essentially for free. If you need a lot, make a lot. If you need more voltage, add on more cells with couplers. If participants and students in your workshop or class all make their own, they can do it together, maybe even doing a manufacturing project to create many for future use.

For some time now, I have struggled with the expense and scarcity of battery holders. Costing anywhere from a dollar to three, they can raise the price point of a project, though they do look nice and work well. Since they are an item that most stores don't carry, you will have to order battery packs for projects that you intend to do. If you're planning a workshop or class with 25 people and want to use plastic battery holders, order ahead and pay up.

Plastic battery packs are also pretty easy to ruin if the ends of the wires are short-circuited accidentally or intentionally. A short circuit will heat up the batteries, which will then melt the plastic around one or both of the springs, causing the pack to fail. By making a battery pack, your participants and students can free themselves of the various barriers that purchased battery packs present for first run and experimental projects. For more formal projects, you or they may want to dig into the budget and buy some packs for a more polished look.

My first designs were done with cardboard from the recycling bin. I also made these with side by side arrangement. The way I am doing them these days is all in a line, which is probably not as sturdy or compact, but is definitely quicker. If you develop a better way of making these battery packs, please share pictures in the MAKE Flickr pool, and show us some links to them in action on projects.

Skills in this project:

Manufacturing
Trouble shooting and the design process
Identifying a conductor and insulator
Testing for electrical continuity
Testing for voltage
Designing for voltage

Materials you will need:

Duct tape
Tin foil
Batteries, AA or AAA are good to start with
Rubber band
Stranded wire

Tools:

Scissors
Utility knife
Wire cutters/strippers
Voltage/Ohm meter

Time Frame:
Half an hour, after you get the hang of it, you can make one in less or make several all at once.

Mastery Objective:
Students and participants will know how to make a 3 volt or more battery pack using readily available materials so that they can use them in electricity projects.

Process:
Gather your supplies.
Make the tubes
For each battery pack, cut 3 four inch strips of duct tape. One will be the coupler, two will be for end caps.
On each strip, cut a 1 inch square out of one end.
fold the strip in half, leaving exposed a 1 inch section at the end. Be careful that the other adhesive is not exposed (it could stick to the battery later)
Roll the strip onto a battery to make a tube. The exposed adhesive tab in the previous step should be the last section on.
Do this to make three of these tubes.
Make a coupler and end caps
Crunch up or fold up some tin foil and put it in one of the tubes. This will help ensure that there is good electrical contact between the batteries.
Put a battery into each side of the coupler. One should be positive end in, the other should be negative end in.
Slide a tube over each end of the exposed batteries.
Fold up a 1" x 2"section of tin foil so that it makes a flat band of foil. Make two of these.
Fold over the end a couple of times so that it is a bit thicker.
Put this thicker end over the end of one of the batteries in turn.
Place a 3/8" to 1/2" wide section of tape over the end of the battery and end cap.
Hold the end caps in place with a piece of tape. You will want to remove the tape when the battery dies or needs to be recharged, so maybe fold over the end to make a pull tab.

Extensions:
Test for continuity
Put your meter on either the continuity setting or the ohms/resistance setting. When you touch the probes to an object that is a conductor like two ends of a stripped wire, you will have continuity: the meter will beep in the continuity setting or it will show numbers in the ohms/resistance setting. Electricity can travel between these two points. If you do not get continuity, such as on a piece of plastic or glass, or if one end of the wire is not stripped, electricity cannot travel easily between these two points. This is an insulator.
Increase your pack's voltage
If your project needs 4.5 volts, 6 volts or more, you can add to the standard pack by slipping another battery onto the pack with another coupler. AA and AAA batteries are 1.5 volts each, so when you connect your batteries in series like this project, each battery you add boosts your voltage by 1.5 volts.
Add wires
Cut two stranded wires, about 2" to 4" long.
Strip the ends about 3/8".
On the end that will connect to the battery pack, spread the strands of the wire.
On the end that will connect to your circuit, twist the wires together. If you have access to a soldering iron, tin the wires to keep them together.
Test your pack and fix if needed
Put your meter in DC voltage mode and touch the probes to each of the wires.
The voltage for two batteries should read 3 volts. A (-) symbol in front of the number just means you have the probes on the battery backwards.
If you get 0 volts, you may need to press the pack together to get a better connection. In this case, you can hold the pack tighter together with a rubber band or carefully tape the caps so that they fit tightly.
Another problem that could give you 0 volts is that the batteries could be in the wrong direction. The negative of one battery has to touch the positive of the next battery.
Use your battery pack
You can use your new battery pack by twisting the wires on the pack to the wires on your circuit project.
You can also solder a 9 volt battery top onto your pack wires so you can use the standardized clip of the 9 volt system.
You can also twist your wires onto a connector cut from a power supply.

More:

Teach your family to solder! Take a few pictures tagged as "MAKEcation" and put them in the MAKE Flickr pool by September 9th to enter to win a $100 Maker Shed gift certifiate!

August 28, 2009

Make: Projects - Polycube puzzles from blank dice

A number of interesting assembly puzzles can be made from pieces consisting of simply joined cubes in various numbers and arrangements. Piet Hein's Soma Cube is a notable example, consisting of all the simply joined non-convex polycubes having four or fewer units. Generally, a polyomino or polycube puzzle is presented as an outline or volume to be filled in with a certain set of pieces. It is up to the solver to figure out how to pack the pieces to fill the specified form.

Among the more interesting of the polycube puzzles are the solid pentominoes. The flat pentominoes are commonly used in early elementary education programs, so many readers will doubtless be familiar with them. Extruding the flat pentominoes by one unit in the Z-dimension gives the set of what are traditionally called "solid pentominoes." They can be used to solve any flat pentomino puzzle, but also to create various 3D shapes. The 3D puzzles are considerably more challenging.

To make a satisfying polycube puzzle requires that the pieces be dimensioned very accurately, so they will always pack closely regardless of their arrangement. To achieve this accuracy with common hand tools is very difficult. However, blank dice provide a convenient and inexpensive source of accurate, precise unit cubes which may be joined to create the various pieces. The use of translucent dice is recommended, both because they look cool and because they're gauranteed to be acrylic and hence strongly bondable with standard acrylic cements. All the opaque dice I've tried to glue have proven highly resistant to adhesives of all types; I suspect they're made out of polyethylene.

Tools:

Combination square or other accurate inside right angle
Steel cookie sheet or other magnetic surface
About a dozen 1/4" cylindrical supermagnets
Small paintbrush, e.g. #0

Materials:

60 blank translucent dice (I used 16mm dice, 20 of each in red, green, and blue)
Acrylic cement
Soap & water
Isopropyl alcohol

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August 22, 2009

How-To: Quick, cheap soldering stand

Teach your family to solder! Take a few pictures tagged as "MAKEcation" and put them in the MAKE Flickr pool by September 9th to enter to win a $100 Maker Shed gift certifiate!

If you are looking to introduce soldering to your classes this school year, you should consider having students use a soldering vise or other holder to secure the circuit board. Keeping the components in place will help students get the hang of soldering quicker than if the board and parts are loose on the table or held by hand. I've been messing with this idea more since using the PanaVise my brother employed to solder the boards for his HeathKit amateur radio back in the day. While super nice to use, a well-made vise like this is too expensive and too easily broken for classroom use. This design can be easily made from readily available supplies from the supply cabinet and a few pieces from either maintenance or home.

My first iteration of the design was pretty simple, a scrap of 1"x3" strapping placed onto a scrap of 3/4" plywood. On the strapping, I screwed down a binder clip with a washer to help the sheet rock screw hold down the handle of the clip. I had some ideas of using water bottles from the recycling bin to hold parts, but plastic near hot iron is a bad combination. There were a few problems with the design, so I made another run at it. The idea behind this project is to create a functional tool, which should be something that kids could make themselves for use at home, or a teacher could bang out a bunch of them pretty quickly and inexpensively to set up several soldering stations.

Skills in this project (you can pick which ones you want to focus on):

Measuring for a cut
Cutting with a handsaw
Cutting with a power saw like a miter box
Designing with CAD (extrusions, assembly, or if you want to get hard core, you can even design the screws with a revolve and put threads on them too)
Making and following drawings for manufacturing
Manufacturing processes
Mass production of a single design

Materials you will need:

2 Binder clips
6" Scrap of 2"x4"
6"x9" Plywood, 1/2" or 3/4"
5 Sheetrock screws 1 1/4" or longer
2 Washers to fit the screws

Tools:

Ruler or tape measure
Pencil to mark your cuts
Saw (hand or power)
Screwdriver or screw gun
Safety goggles/glasses

Process
Start with a scrap of plywood. 6 inches by 9 inches should be plenty, but you can make it bigger.
Measure for your cuts and mark them on the wood in pencil.
Cut the 2"x4" to fit the short dimension of the plywood.
Align the 2"x4" so that it is about 2 1/2" from one end and mark the plywood. This will allow you to attach a holder such as a mint tin for solder and other supplies later.
Flip the plywood over, ideally, put the 2"x4" in a vise to keep it secure and screw the plywood to the 2"x4" with three screws.
Flip it over and place the two binder clips on the 2"x4" so that they are evenly spaced.
Place the washers on the screws and secure the binder clips in place.
Your soldering stand is ready for action!

Extensions
Storage
You may want to screw a mint tin or two on the board. This will allow you to hold things like short lengths of desoldering braid, solder, LEDs, switches, resistors etc. You will need screws that are at least 1/8" shorter than the thickness of the wood you are screwing into.
Soldering iron holder
You could make an iron holder with a 3/4" screw eye on the side of the upright. Making sure the heat from the business end of the iron is shielded should be part of your design, this could probably be done with a soda can, which can be cut with scissors and held with a short screw or two.
Soldering iron cleaner
Brass or copper pot scrubbers make good tip cleaners. Use a short screw with a wide fender washer (small hole, wide disk) to secure it to the plywood. Steel wool should not be used for a couple of reasons, apparently it scratches up the tip of the iron, and sooner or later, kids will discover that it is flammable, which could invite a visit from the local fire department or its' representatives.
Computer Aided Design
You can introduce students to the powerful ideas around CAD by having them make a virtual model of the stand either before or after building.

For well under $5, you can have a soldering station for your students to hold their work. If they use this as a way to also learn about manufacturing and computer aided design, you can wake up some other useful interests as they get ready to explore electronics.

More:

In the Maker Shed:

Discoverelectronics Kit Crop

DIY Design Electronics Kit

August 14, 2009

Make: Projects - Bottle cutting

There are lots of ways to do this particular trick. You may have seen bottles "cut" using a bucket of ice water, a string soaked in fuel and set alight, a hot narrow gauge resistive wire, or some combination of the above. I've tried all of these ways, at one point or another, with varying degrees of success, and I'm reporting here the method that gives most consistent results for me. But if you're interested in trying some other way, by all means experiment. Glass bottles are freely available just about everywhere, and you can always recycle your mistakes.

Regardless of which of these methods you favor, "bottle cutting" is generally a misnomer, as what's really going on is a process of controlled breakage. (Unless, of course, you're actually using a tile saw or something similar, in which case I'm prepared to agree it's really "cutting.")

Anyway. Glass, molecularly, is mostly silicon dioxide, but it's distinct from crystalline solids like ice or table salt in that the molecules are not well-ordered in space. You may have heard some balderdash about how glass is really a liquid with practically infinite viscosity; generally the swelling of ancient cathedral windows at the bottom is sited as evidence to that effect. Well, it's not true: There is, to my knowledge, no reliable evidence that glass will flow at room temperature regardless of how long you wait. Turns out cathedral glaziers made their windows thicker at the bottom on purpose.

But as an analogy, "infinitely viscous liquid" is not a bad way to understand the random molecular ordering of bulk glass. The upshot of this anisotropy is that glass does not cleave in orderly ways: Cracks tend to wander off in random, unpredictable directions, and shattering can easily occur due to internal stresses. There is, therefor, an element of luck involved in the bottle cutting operation, but with a bit of practice and good technique you can make it work most of the time.

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August 12, 2009

Intern's Corner: Chladni Plate, the alternate build

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 Meara O'Reilly, projects intern

I'd been wanting to make a Chladni plate for years, and testing out Edwin Wise's Chladni plate project for MAKE, Volume 16, was just the jump-start I needed to start tinkering around with making my own voice coils and drivers, like this one:

One of my heroes, David Tudor (an experimental music pioneer and John Cage collaborator), used drivers as the basis of his famous Rainforest installations, turning ordinary household objects into speakers and creating suspended "forests" of whispering resonant frequencies.

The transducers that Tudor often used to drive these objects are still available today (Rolen-Star transducers from Stockton, Calif.), and I built a plate reverb a few years ago using a drum cymbal as the plate, driven by a Rolen-Star, and picked up and amplified by a contact microphone.

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August 7, 2009

Make: Projects - Giant snow globe

What's that you say? You don't need an 8-inch diameter snow globe? Especially not one featuring a vignette of Al Pacino as Tony Montana in the climactic battle scene from Brian De Palma's Scarface? I say you're wrong: You need one of these. You need one so badly you don't even know it yet.

This project began when I, myself, realized that need; that deep need that every man knows sooner or later, in his life, which can only be satisfied by a say-hello-to-my-little-friend snow globe. I scoured the tubes looking for a suitable Tony Montana figurine, and though I found several, the only one featuring suitable full-auto-enraged-coke-frenzy action was MezCo Toys' Tony Montana ("The Fall" version), which is 7" tall. That's way too big for even the largest empty snow globe I could find. (It turns out, incidentally, that sourcing empty snow globes online is a bit of a trick. There a couple of crappy kits on Amazon, and a predictable selection of snow-globe photo frames, but for the real stuff you have to go to snowdomes.com.)

So I was forced to consider other options. Then one day at the hardware store I looked at a shelf full of glass lamp globes and the light bulb went on. And although the round, perfectly clear variety is a bit harder to find, I was able to run one down on eBay without spending too much time on it. The globe I used is made of glass, 8" in diameter, and features a 3.5" opening, which are ideal dimensions for the MezCo Tony Montana. Turns out the same globe is available in clear acrylic, and frankly that would be a better choice because of the reduced weight and danger of breakage.

Next I had to figure out how to seal the opening. It wasn't long before I remembered seeing, in some lab that I worked in at some point, a really giant black rubber stopper. It took a bit of research, but it turns out the biggest rubber stopper manufactured, which is #15, fits very well into a 3.5" globe opening. These stoppers are commonly available in natural (i.e. off-white) and black rubber. I found a black #15 rubber stopper on eBay for not too much, and was able to figure out a clever way to seal it tightly into the neck of the globe without having to use adhesive, sealant, or tape.

The final problem was the snow itself. Turns out the composition of snow globe snow is a closely-guarded trade secret, and although you can buy small packets of it as part of commercial snow globe kits, I couldn't find anyone selling it in bulk. Glitter can be used for this purpose, but it was totally inappropriate to serve as snow in the context of my vignette. A craft site put me on to the idea of using crushed eggshells, but it took some experimentation to figure out how to treat, clean, and grind them to make good snow.

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July 31, 2009

Make: Projects - Mold concrete pots in scrap styrofoam

About a year ago Marc linked to the original version of this tutorial on my personal page. This is a revised version with more detailed and user-friendly instructions.

The idea here is to use a simple, inexpensive concrete mixture to cast decorative containers using common trash items as sacrificial mold elements. Styrofoam packing inserts, in particular, are available in an endless variety of shapes; the trick is to cultivate an eye for the negative spaces that are molded into these inserts, and set aside the interesting ones to use as outer forms. Inner forms, obviously, should be simpler, because the inside of the pot is not going to be visible.

Tools:

Wheelbarrow or other mixing bin
Shovel or other mixing tool
Tamping rod, e.g. 1.5" wooden dowel or closet rod, about 12" long
Knife or other metal straightedge
Old towel, preferably undyed
Saw or plastic pipe cutter
Hammer
Punch

Materials:

Styrofoam packing insert with interesting negative space
Beverage cup, food container, or other suitable inner mold
Play sand
Portland cement
Water
Plastic garbage bag
Short section(s) 1" pipe or other suitable drainage hole mandrel

Step 1: Gather your mold elements

I used a Styrofoam block I found discarded in a hallway in the UT chemistry department as an outer mold. It contains four identical cylindrical recesses and was originally used to package 4L glass solvent bottles. The inner forms are nested polyethylene tubs of the type provided at many grocery stores to package bulk dry goods.

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