By Steven Lemos, engineering intern

Making the Hydrogen-Oxygen Bottle Rocket (that Adam Savage is posing with on the cover of the new MAKE, Volume 20) was a pretty basic endeavor, with the exception of the circuit. The original schematic diagram had a flaw in it, but only after we breadboarded the circuit -- twice -- did we catch it.

I guess that's the reason we MAKE interns build the projects that run in the magazine, so it's us who bang our heads against the table and not you. I will kindly take that cookie now.

The experience showed me that, sure, when working with electronics it's easy to misplace a component or wire, or completely miss something, which I already knew, but it's just as easy to have a diagram be the culprit. So a word to the wise (a word I'm sure all the experienced hobbyists have already discovered for themselves): if you take care when putting together these tedious circuits it will pay off, for if you can trust in your work, then you'll know the culprit lies in the plans, and you won't spend hours chasing that metaphorical wild goose.

Twice we breadboarded this bad boy before discovering an error in the schematic -- so you won''t have to.

But on to the actual launch. :) We had talked to the local electronics store owner, who at the time was making his own hydrogen using a more sophisticated apparatus, and who was interested in what we were doing with ours. So he came to watch, and brought along his professional pyrotechnician friend, who showed us how to make fuses with 12V and tiny resistors (basically the resistors pass so much current that the wire heats up and can act as a fuse to light stuff -- voilà, cheap fuses).

Our beautiful 2-stage HHO rocket ready for test launching -- before being crippled by a crash.

The first launch was a success, with the two stages going off rather quickly in succession, so we dialed in a little more delay time in the circuit before the stage 2 ignition. This was good and bad. We got more height out of the rocket on our second launch, but on its return it landed electronics side down. This resulted in our circuit behaving oddly.

So, not ready yet to call it a day, we began firing off only one stage at a time, adjusting the proportions of HHO (hydrogen and oxygen gases), water, and air, and testing the makeshift fuses, which worked fine for a single stage, but due to the time they take to ignite (3sec@12V) might not work for 2 stages.

We probably launched 12 times that day, attracting passersby. Good weather, new friends (who like blowing stuff up), and multiple launches. All in all, a good day. Houston, we have liftoff.

• Related: MAKE, Volume 20: "For Kids of All Ages"

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

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.

Read full story

By Eric Chu, engineering intern

Let's admit it. We've all had thoughts of building our own robot of mass destruction. Well, I was able to do just that for my college class Engineering 102: Robotics Design Challenge ... sort of.

Last spring my class used the Lego NXT robotics platform to solve two engineering challenges. The first was to build a robot that can cross a pit filled with ping-pong balls, racquetballs, and mini whiffle balls. The second was to build a robot that navigates through a maze, distinguishes between orange and blue balloons, and pops all the orange balloons. Both challenges had a time limit of 2 minutes.

Meet Poke-e, my team's balloon-popping, maze-navigating robot:

Poke-e is made completely out of Lego Mindstorms NXT parts, except for the straight pins that are attached with green duct tape (generously donated by my friend, Dan). I felt horrible putting the non-Lego parts on, but at least it looked pretty killer afterward!

By Steven Lemos, engineering intern

For a school project in my AutoCAD class, my group and I decided to design and build a hovercraft. At first we were planning a full-size, ride-on hovercraft, but after meeting and brainstorming it was clear we didn't have enough time to build one. So we decided to build a smaller version, using R/C controls. This was made possible by a friend's surplus supply of assorted R/C airplane parts, including motors, receivers, and controllers.

The hovercraft took one month to design using Autodesk Inventor software, two months to build working mostly on weekends and some school nights -- and 1 afternoon with the MAKE interns to wreck! Check out the video:

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.

By Ed Troxell, photo intern

When I landed my internship here at MAKE it was my real break into the magazine industry. I remember telling myself that if I could just get my foot in the door, the rest would fall into place. Well, it did. Since joining MAKE over a year ago, my life has not been the same -- not only have I worked at a great magazine, I've launched my own magazine, MIX IT UP.

I was hired a MAKE editorial intern, which really helped me get a sense of what goes on when putting together a magazine: finding topics to write about, finding writers, assigning deadlines, making sure people meet those deadlines, fact-checking articles, proofing them, all while having staff meetings and conference calls with those who work in other locations.

While learning all this, I was finishing up my studies in communications at Sonoma State University in Rohnert Park, Calif., where I was photo editor on the school newspaper, The Star. About 6 months later, I was switched over to become MAKE's photo intern, which turned out to be perfect since I was already doing photography.

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.

By Eric Chu, engineering intern

Hammers have been used for millions of years, evolving from a primitive stone tool to the combinations of metals, woods, and plastics commonly seen today. Here's my version in solid steel.

I made this steel hammer in my beginner's manual machining class, for the class final. This is no ordinary hammer. It's roughly twice the weight and size of a normal hammer, so it has lots of power behind it when swung! I made it using a manual lathe and utilizing most of the lathe's tools. Check out my results:

The hammer is actually made of 2 parts: the head and the handle.

Here at MAKE, we're lucky enough to have a rotating stable of interns who build and test most of the projects before we go to print each issue (and sometimes photograph any missing step shots). They also haul supplies from the warehouse, shop for tools and materials, and come up with projects of their own on a surprisingly regular basis. We also work them to near death before, during, and after each Maker Faire -- packing pallets and building projects to send to the fairgrounds beforehand; setting up booths and greeting the public for 12-plus hours a day during the event; and unpacking trucks when everything comes back to our offices after the fact.

In exchange, they get to have one of the most highly coveted jobs in the land. Seriously. I've had top-level editors ask if they could trade their job for an internship at MAKE, not to mention engineers, the parents of our interns, and just about anyone who gets a look at the Make: Labs, where the interns build, sew, hack, hammer, drill, and solder day in and day out.

Now we're offering our website readers a look into the fabulous lives of the MAKE interns. Twice a month, the current interns will offer up stories about the projects they're working on, the trouble they've gotten into, and what they plan on building in the near future.

Jacob McKenzie, one of our two original interns who began working for us in the fall of 2005, has always said that we've pretty much ruined him for life in terms of ever having a cooler job. Nonetheless, Jake left his internship in 2007 to finish his bachelor's degree at UC Berkeley. He graduated with a 4.0 GPA and a degree in mechanical engineering. During the 2008 winter break, we called him up and asked him to demonstrate a few of our previous projects for the TV show, Quest, which were well-received and a blast to see get filmed in our very own Make: Labs. Most recently, Jake was accepted at both Stanford and MIT for graduate school. After much thought, he chose MIT, where he'll begin the next part of his journey this fall. He's promised to keep in touch, and let us know if he ever finds a cooler job than MAKE Intern. He remains unconvinced that he will, but his future looks bright to us.

Tune in on Wednesday, July 29, for the first of many first-person accounts about interning at MAKE!