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Hey makers! We’re looking for true stories about dangerous maker experiences for an upcoming issue of MAKE. Do you have one to share?

I’ll get the ball rolling by sharing one of my own:

Why You Shouldn’t Make Smoke Bombs in Your Friend’s Kitchen

When I was 12 years old I got my hands on a copy of Abbie Hoffman’s Steal This Book, a guidebook for pranks, protests, and overthrowing the system. My favorite part of the book was the “People’s Chemistry” chapter, which had recipes for making stink bombs, smoke bombs, Molotov cocktails, sterno bombs, aerosol bombs, pipe bombs, et cetera.

Here’s Hoffman’s recipe for Smoke Bombs:

NewImage.pngSMOKE BOMB

Sometimes it becomes strategically correct to confuse the opposition and provide a smoke screen to aid an escape. A real home-made smoke bomb can be made by combining four parts sugar to six parts saltpeter (available at all chemical supply stores). This mixture must then be heated over a very low flame. It will blend into a plastic substance. When this starts to gel, remove from the heat and allow the plastic to cool. Embed a few wooden match heads into the mass while it’s still pliable and attach a fuse.

The smoke bomb itself is non-explosive and non-flame-producing, so no
extreme safety requirements are needed. About a pound of the plastic will
produce thick enough smoke to fill a city block. Just make sure you know which way the wind is blowing, Weathermen-women!

After a bit of research I learned that the chemical name for saltpeter is potassium nitrate. I called the pharmacy department at the local Kmart and they told me they had it in stock. I rode my bike over and bought a pound. When I got home I set up my Boy Scout camping stove in the backyard and melted a batch of potassium nitrate and sugar in a frying pan. After letting it cool and forming it into a lump, I placed it on the asphalt of the cul-de-sac I lived in and lit it with the match. An astonishing amount of opaque white smoke gushed out of the bomb. The smoke bomb itself liquefied and bubbled like molten lava for quite a while afterward, causing damage to the asphalt.

I invited my friends over and we made more. The next day we bought every container of potassium nitrate that Kmart had in stock. The guy at the pharmacy counter gave us a funny look, but didn’t ask us why we were buying it.

With all that potassium nitrate we wanted to make a big batch so we’d have plenty of smoke bombs on hand for Fourth of July. The small camp stove I was using would not be sufficient for our ambitious plans. I asked my friend if we could cook it up in his kitchen. He thought it was a great idea. We went to his house, dumped a huge amount of potassium nitrate and sugar into a 8-quart pot and cranked up the burner on the range. His mother asked us what we were doing, and we explained that we were making smoke bombs. She asked if it was safe, and I told her that we had made it a bunch of times before, and no one had been hurt (which was true). Potassium nitrate is white, like sugar, and it looks innocuous, so she just told us to be careful and left the kitchen.

My friend and I took turns stirring the mixture with a wooden spoon, waiting for it to start to get soft and melt. But nothing was happening. We turned up the burner. Ten minutes later, still nothing. Suddenly, my friend remembered that he had the new 10 Years After record and asked if I wanted to listen to it in his room. “Sure,” I said. “We can check on the smoke bombs in about 10 minutes.”

We were in my friend’s upstairs room for less than two minutes when we heard a strange rumbling sound, kind of like a vacuum cleaner but lower pitched and more throaty. We looked at each other with fear and ran out of his room and down the stairs. We heard my friend’s father scream “Holy shit!” By the time we got to the bottom of the stairs the entire first floor was filled with opaque white smoke. I felt like I was lost inside a giant bucket of milk. In the kitchen, we could see puddles of molten smokebomb mixture on the floor, counters, even dripping off the ceiling. The puddles were glowing red, barely visible through the smoke. My friend’s dad had run to the backyard to get the garden hose and was spraying water into the pot and into the burning puddles of smoke bomb lava.

Fortunately, no one was hurt. The property damage wasn’t too bad, either, but I got grounded nonetheless. I was especially thankful that my parents didn’t forbid me from making smoke bombs. The only stipulation was that I had to go back to making it in our backyard with a camping stove.

Okay, that’s my story. What’s yours?

Mark Frauenfelder

Mark Frauenfelder is the editor-in-chief of Make magazine, and the founder of the popular Boing Boing blog.


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  1. [...] Read the full article on MAKE [...]

  2. [...] Hey creatori! Siamo alla ricerca di storie vere di esperienze caffè pericolose per un prossimo numero di FARE. Hai uno da condividere? [...]

  3. vk2tds says:

    I was moving a bookshelf on a brick feature wall just after buying my home. This involved drilling wooden dowels into the brickwork to hold the bookshelf using my new Rotary Hammer Drill purchased from the local Home Depot clone.

    The problem was that I was using a 12mm drill bit, and tried to drill between two bricks that had a 10mm spacing. I was standing on a chair so I had the height, and started using the drill. Unfortunately, the drill caught and rotated about 270 degrees. What stopped it was my forehead.

    As you can imagine, a 1000W drill has a bit of weight behind it, and hit me with some force. Thankfully I was not knocked off the chair, but I was left with a lot of blood and swelling. I decided to stay up most of the night in case I started getting a headache, and when I saw the doctor the next day I ended up getting 11 stitches.

    1. Craig Couden says:

      Hi vk2tds,

      My name is Craig with MAKE magazine. Great story! We are turning Mark’s post into an article for the magazine and would possibly like to include your story in the article. We’d like to include your name and location, so please email me at ccouden@makermedia.com to continue the conversation. Thanks!

  4. Ryan says:

    Too many to even remember. The most memorable was shorting 1.5KW of LiPo cells through a pair of tweezers which literally melted into a ball of metal and a shower of sparks. By some magic, I was unharmed. Kept the tweezer remains as a memento.

    Also had run-ins with smaller LiPo packs which did burn me a few times (one pack caught fire). Taken 400V off a strobe light circuit, although I’ve never been hit with wall power.

    I’ve taken a quadrotor to the arm and still have the scar. I’ve over-RPMed carbon fiber blades which got thrown *through* the drywall. Unintentionally destroyed thousands of dollars in electronics for various reasons (normally incompetence). Ive also had a quadrotor go to maximum power *indoors* and smash into the ceiling so hard that the motor shafts left a perfect square pattern of holes about an inch deep.

    Lit my hair on fire, among numerous other flammable objects while lampworking/soldering/glassblowing.

    Ive also had the occasional CNC crash which often ends with the destruction of a tool.

    I’m not actually as irresponsible as this makes me sound – most of these happened a long time ago, and I’ve picked up the habit of always wearing the appropriate safety equipment regardless of what I am doing. Its just that after going three days without sleep before a competition mistakes tend to get made…

    1. Craig Couden says:

      Hi Ryan,

      My name is Craig with MAKE magazine. Great story! We are turning Mark’s post into an article for the magazine and would possibly like to include your story in the article. We’d like to include your name and location, so please email me at ccouden@makermedia.com to continue the conversation. Thanks!

  5. Dave says:

    Too funny! Yes, probably too many to recall for me, too.
    Pyro related, as a teen: Calcium carbide chunks dropped into a can of water, with another, larger can inverted over the top. Fuse in a hole punched in the bottom of the “lid”. This would reliably throw the lid can 20-50 feet up. One went off sideways when I was demonstrating it, and nearly hit my uncle in the head.
    Sorta pyro related: We would fill dry cleaner bags (1/2 mil poly) with natural gas, tie on a fuse, and launch them at night. Tried for a massive collection of ~10 bags, with a penlight as well as the fuse. It rose up maybe 10 feet, then flew horizontally onto the neighbors shake roof. God apparently reached down and pinched out the fuse!
    Also did the same thinkg with the tweezers, but in biology class in high school. Idly tapping them on the bench while watching a film, and managed to insert the points into an AC outlet. Next day, the teacher suggested I should use two tweezers next time, one in each hand…

  6. Tom Dimock says:

    Two memorable ones. The first happened abou 43 years ago (as you can guess, I’m now a senior citizen). I was welding on the base of an 8′ tall sculpture with an oxy-acetylene torch when the sculpture fell over on me. The torch was knoked out of my hand, flipped over, and the flame made a quick pass across the back of my hand, leaving charred flesh in its wake. Very painful, but I recovered from that one with no visible damage. I was not so lucky 31 years later, when I was cutting a groove into the bottom of a piece of wood on my table saw. The wood was trying to ride up, so I was holding it down on the far side of the blade – something I had done many times before. This time the wood caught and kicked back and dragged my fingers into the blade. Lost down to the first knuckle of my middle finger and suffered lesser damage to my index and ring finger. I ordered a SawStop saw the next week (great saw, and it won’t cut any fingers off in the future).

  7. dbarak says:

    Back when I was young and stupid (I’ve since graduated to much more mature mistakes), I was casting some small resin parts using silicone molds. Some had a few bubbles, and I’d read somewhere (no, I can’t blame it on MAKE – damn!) that a vacuum chamber would draw the air out of the resin.

    I’m a pretty smart guy, with an IQ somewhere around 8, so I cobbled together a vacuum chamber. I took a plastic cereal bowl, cut a hole in the bottom, stuck a plastic hose through it, and sealed it with some sort of caulk. I poured resin into the mold and placed the bowl over it. I may have added caulk to the rim of the bowl, I’m not sure. I flipped the switch on the little vacuum pump and waited.

    Have you ever heard the huge boom that an imploding cereal bowl makes when it shatters into dozens of sharp pieces? Thankfully I was living in a suburban area Ohio at the time, where big booms make up the soundtrack of a normal day.

  8. dbarak says:

    @Ryan, your LiPo story reminded me of another fun time for me, this time just a couple years ago once I moved up to more elaborate near-death experiences.

    I was taking apart an old UPS unit whose batteries were dead. I felt a bit of a tingly buzz and I figured some capacitors must have still had a bit of a charge. I finished my demolition project for the day and set it in a plastic trash bag to insulate it from the carpeting and the cats.

    I came back to it a day or two or three later and began to work on it again. I felt another tingly buzz and… yep, it was still plugged into the wall socket.

    My wife only lets me play with rubber hammers now.

  9. Flecko says:

    While installing a giant industrial machine (that’s all the more specific I can be) one of my crew members hooked up the 440 3-phase incorrectly to a power supply. I had worked with him for a good long while, so I wasn’t worried about checking his work before turning the mains power back on to the machine. I asked everyone if they were done with their work, everyone said yes, so I flipped the switch.

    Smash cut to the power supply exploding, and me being angry. I walked over and knelt down to see what was wrong. I put my hand on the outside of the power supply while I was kneeling down, and my elbow grounded to the machine’s chassis. Well, it turns out he had hooked up all 5 of the wires incorrectly, so the outside of the chassis was 1 leg of the 3 phase power, and the machine chassis was ground. So, with my hand on the outside of the chassis (which was now hot) my elbow touched the machine chassis (which was ground) which blew me off the machine.

    Lesson learned. (I was 26 at the time keep in mind.) ALWAYS turn the mains off before investigating failures. ESPECIALLY when high voltage multi-phase AC is involved! Man…that tickled…

  10. Paul Shemeta says:

    I’ve had so many it’s not funny. Here’s just one. I live in Seattle, every year we have unlimited hydroplane races on Lake Washington. The Blue Angels fly over, and back in the day 100,000 people would show up for Seattle’s biggest beer bash. The place to watch the action from was out on the lake. The problem was, unless you paid to get on the front row of boats you couldn’t see anything. No problem, we built a series of bigger and bigger floating platforms, our final one would hold 10 people 18 feet off the water with a seat on top 26 feet off the water. The structure of this thing was 3 pieces of 40 foot long 8″ aluminum irrigation pipe arranged to make a big pyramid, the deck hung off the pyramid. It floated on foam blocks in 150 feet of water.

    Problem – traffic control! In our earlier days we used a rope ladder, if it got too crowded we’d just pull up the ladder. Later on we got lazy and just hung an aluminum ladder overboard, it was much easier to climb but a real hassle to pull up so we just left it down.

    We became victims of our own popularity – too many people climbed up, sinking one of the floats and making the whole thing with 12 people on it to topple over in slo-mo. Fortunately nobody got hurt, but the Coast Guard came to see if everybody was OK and after that, the boat race people changed the rules out on the water to outlaw our tower! Now only 1 row of registered floating vessels can be out on the water watching the races.

    1. Craig Couden says:

      Hi Paul,

      My name is Craig with MAKE magazine. Fun story! We are turning Mark’s post into an article for the magazine and would possibly like to include your story in the article. We’d like to include your name and location, so please email me at ccouden@makermedia.com to continue the conversation. Thanks!

  11. Some_dude says:

    Not much here, but at the age of around ten I got shocked with a ~20Kv spark from a tool made to find leaks in seals.

  12. To quote a magazine recently in the news, it’s NOT a good idea to “make a bomb in the kitchen of your Mom.”

  13. Kyle Brinkerhoff says:

    i was about 18 at the time but i had just created a massive shoulder fired pneumatic air cannon that i was going to use like a air soft bazooka, for playing soldier in my backyard, i was tired of always getting creamed by my friends when we played so i was getting a little “surprise” ready for them, this cannon consisted of a tank with 200 psi in it with a piston actuated valve, with a 3 foot long barrel that was 1 1/2 inches in diameter, for a test to prove to my parents that it was going to be “safe” to fire at my friends i poured soft air BBS down the barrel until it was about half way full and then capped the BBS with a milk jug cap so they wouldn’t roll out, then i pointed it at the wooden fence in our small backyard and fired. to my surprise i quickly learned the ricochet’ing nature of the plastic BBS fired out of a cannon with 200 psi behind them while striking a hard surface. needless to say i was now placed on the receiving end of around 500 BBS, luckily i had the sense to put on safety glasses and hearing protection but the rest of my body was pelted mercilessly in a maelstrom of red plastic BBS, yeah it was stupid, and yes did it hurt, but was it worth the money to build such a device? definitely!, after that i repurposed it as a potato cannon and its been a blast “literally” ever since.

  14. randomjnerd says:

    Lets see, there were a lot of them. Self imposed limit of before I graduated high school.

    I was on a Junkyard Wars/Scrapheap Challenge team (we were the first Americans, back in 2000 http://the-nerds.org ). A standard topic of discussion between teams (usually while in a van getting hauled 3 hours to a testing site) could basically basically be summed up as “How the hell did we survive our childhoods, especially with all our fingers still attached?”

    I blew my first fuse before I was walking. It was 1958, long before caps for outlets occurred to anyone. I must have seen my parents plugging things in, so I did too. A pair of scissors. It might not have done much, but the outlet had a metal cover plate. My parents didn’t replace the now scarred plate, to serve as a reminder.

    I have always known how to solder. I learned at such a young age, that I can’t remember there ever being a time when I didn’t know how. My father had a business that involved him soldering stuff together on a table in the spare bedroom (before my sister arrived, and it became her room). Apparently I watched, and taught myself how. (I also apparently began by plugging in the iron, and just melting solder on top of everything.) My mother said I never burned myself back then, but at around 6 or 7 when I tried to assemble my own radio gear, she said she would hear a yip every 5 minutes or so.

    You can tell when I got access to propane (my very own bernzomatic) in my youth, as pictures of me ceased to show eyebrows. (think it was my 10th birthday present, might have been 9 – my friends got bb guns that year, I got tools. I like how my parents thought).

    I was working on my oscilloscope (a venerable even then Dumont) and brushed against the high voltage terminal on the CRT. (tho most of the injury was due to the stuff my arm scraped when I yanked my arm away).

    I got an 11kv/50ma filtered DC power supply out of some mil spec device, likely having to do with radar. Did you know that a one foot piece of plywood at normal basement humidity levels is enough to complete a circuit? You likely only got a few uA of current to flow, but the coronal effects were impressive. (and for once the current was not flowing into my body).

    Last electrical folly – Back in the days of vacuum tube, and especially around the time that everybody was ditching their old black and white set, for a color one, you could go to the dump and get a great source of electronic parts. A couple of tv sets worth of parts, and a copy of the ham radio handbook, and you could build something capable of screwing up radio reception for several miles around your house. I wound up with a bunch of high voltage (by today’s standards) electrolytic’s I decided to make a big composite capacitor, so I could play with high currents. 1 Farad at 400 volts, using the packaging of the day was a cube a bit smaller than a desk. I could charge it off rectified 220. It was interesting to say the least. (Yea, dump. it didn’t get its name upgraded to landfill, and later transfer station, till long after I moved away) By then I was even wise enough to fit a plastic cover over the output terminals.

    I lied, writing the above reminded me of another one. My high school had an “electronics” shop. Most of what we played with was still vacuum tube operated, so we were used to dealing with those sorts of voltages. We were also teenage males. Take one 60uf 450 volt capacitor. Fit straightened paperclips to the two terminals, and charge it from the bench supply. You then had a weapon you could use against a similarly armed classmate. You would try and get one of your “blades” (the paper clip prongs) to short out your opponents weapon, and render it harmless, so you could use the charge left in yours, to zap them.
    The size of the capacitor, 60uf, and the “blade length”, one standard paperclip, straightened were set by some long (2 maybe 3 years ago, tops) arms limitation talks, and the “rules” were passed down from senior to sophomore….

    Ok, enough electricity, onto chemistry and physics.

    Not particularly dangerous, but: An old model rocket engine got dropped and its ceramic nozzle broke, rendering it non-flyable. So I took out the propellant, put in a small metal dish, and lit it to see what happened. I was outdoors, but I did so next to an open window. The big cloud of smoke it made mostly wound up in the basement.

    I almost got myself thrown out of HS chemistry class for making TNT in class. (actually since they really didn’t have strong enough nitric acid, it was likely Di-NT. – and only a gram or two at that).

    We had a long driveway at home, that was fairly steep, and the low point was away from the street. So it was a regular activity to build some sort of gravity racer, and compete against each other. Needless to say, control and braking (especially braking) were afterthoughts at best. I remember leaving the skin of more than one palm in the blacktop.

    Did you know that aircooled VW transaxle cases are half magnesium? Melt one down in a propane powered foundry, and the result is “entertaining”. How were we to know we needed to melt it under an argon gas shield, it sure looked like scrap aluminum. Luckily we were at a reasonable distance.

    Other home casting projects used lead. In a small space in my basement. (from the old cast iron sewer pipe days, where you would ram in something fibrous (likely asbestos) cover it with melted lead, then when the lead had cooled and shrank, beating it into a seal.) The pot and gas fired melting stove were left over from when my father built the place. There wasn’t much lead left around, till I discovered tire weights.

    Thermite is entirely too easy for the young to make. All you need is a file a wire brush and a pile of rusting metal. You don’t even have to spend any of your allowance. Yea it works better (and is easier to light) if you use powdered aluminum, but your parents won’t get you another etch-a-sketch after the first one got harvested for that purpose.

    Imagine a crossbow built with a leaf spring from a wrecked semi, and some 1″ wire rope for the bowstring. You cock it hydraulically. You use 3/4 inch rebar for your bolts. It wasn’t as powerful as you might imagine at first (I only used two leaves from the spring) but it would happily come out the other side when fired at a car. (an engine block would stop it)

    Time I got some sleep..

  15. John T says:

    Back in school, a few of us were involved in a project to create a rocket car (Plan was to race it). There was a few safety systems in place like guide wires, keys to control ignition etc. Unfortunately, during an early test our procedures for a launch failed slightly. Turns out the ignition system wasn’t disabled properly and the guide wire…well, it wasn’t attached like it should have been. Skip to the final steps of the setup and the motor ignites and the vehicle flies off, does a few loops and hits the ground rather hard. Luckily some very careful diving and running away later and no one is hurt, bar a slightly warm thumb. Very close call that day, one we’ll never forget, and certainly don’t want to repeat. Safe to say that following that, extra precautions were taken and the accident never came close to repeating itself. Although it certainly wasn’t the last time rockets have flown in my general direction, I seem to attract them unfortunately.

  16. Chrisw says:

    This isn’t exciting, but very dangerous anyway. I helped build our high school’s first TV studio. We came in on the weekend and without any supervision pulled all the wires for the lighting grid. We crammed as many wires into the conduits as we could and had a half dozen guys pulling on the wires. Then went around with an ohmmeter to find which wires had their insulation stripped and were shorted to the conduit or other wires. Be they black or white, those became neutrals. We didn’t use grounds.

    Oh , and I found a shotgun shell in the woods, disassembled it, and lit the powder off in the basement in my mother’s aluminum lasagna pan. I expected a flash, but I didn’t expect to be blinded and coughing. I protested my innocence when the smell drifted upstairs. I miss her lasagna.

    One more, at my first job in electronics, I found a 5KW RF dummy load and wanted to see what was inside it. I removed the locking ring, but still couldn’t open it so I turned it on its end to get a better grip. That worked and to my horror, it was full of oil! If I hadn’t turned it over, gallons of PCB laden oil would have poured onto the workshop floor.

  17. Jerry Carter says:

    As a teenager, the simple act of stepping into a basement closet, barefoot, on a damp floor, to reset a breaker switch caused an interesting event I’ll never forget. It wasn’t the breaker panel that got me. In the gloom I put a hand on top of a 220v AC electric water heater tank and closed the circuit between it and the floor through my bare foot. What a ride! Fortunately my center of gravity shifted me away from the tank and thus ended my 15-20 seconds of screaming at the top of my lungs with no way to stop. I kind of understand whit it must be like to be an electric motor. I have no fear, but massive respect and caution, for electricity these days. I always cut the mains when doing electrical work in the house.

    I survived a spectacular “failure to control tool” episodes at the wood lathe in shop class when the chap behind me failed to have an over grip on his gouge and sent it flying into the wall above my head. It ricocheted off and clattered harmlessly across the shop floor. Thankfully the lathes were all set at an angle for just this eventuality.

    Tried clearing a small section of field of weeds to facilitate digging an underground fort. Unfortunately I had no idea that dried grass was so flammable and wound up burning about an acre before the FD got it under control. The wind that day was uncharacteristically westward. had it been a normal day, the wind would have blown the fire towards my parents house.

    As an adult, I did exercise quite a bit of stupidity with a drill press. On one occasion I was putting a 1″ hole in a 5″ x 5″ x 1″ piece of red oak. I stupidly held it with my hand instead of clamping. The Bit locked up and gave me some nice bruises and sub-dermal lacerations. I also had the stupid idea to try to make a router out of it. After making a fence and mounting a bit I tried to do a bit of routing work. After turning it off I realized how dangerous it was to be pushing a piece of wood towards a spinning router bit without a push stick.

    I must conclude that God is merciful: I still have all my fingers and both eyes. May others learn from my mistakes and potential, rather than actual, results.

  18. Eric A. Beatty says:

    I must have a subconscious hatred to drill bits.

    During my CNC training program, I misplaced a decimal point in the feedrate for a drilling cycle when I was putting a 1/4″ hole in 3/8″ thick stainless steel. The combination of the 10X fast feed rate with the drill RPM quickly had the tip of the drill bill glowing bright red (even under the flood of coolant) until I hit the E-stop. I melted the drill tip into a nice sharp vee and thoroughly hardened the workpiece to the point that even a carbide center cutting end mill wouldn’t cut thru it.

    Several years later, I was in a rush to finish some spacers for a customer’s project. The spacers were both 1″ and 3″ thick. I recycled my NC program for the 1″ spacer to create the 3″ spacer. I used a peck drill canned cycle on the 1″ spacer to poke a set of 13/64″ holes thru. When I switched over to run the 3″ spacers, I edited the final Z-depth to the correct value but didn’t change the peck drill cycle to a full retract/chip clearing cycle. The first hole seemed to go OK as I ran the program, but on the second hole, suddenly I heard a high pitched whine followed by a sudden loud clunk and the mill spindle stopped dead!. I nailed the E-stop again and discovered that the drill bit was now a permanent part of the work piece. Since the drill bit wasn’t fully retracting to clear the deeper hole, the chips continued to swirl around in there, getting heated up by friction until they got hot enough to weld themselves to the wall of the hole and the flutes of the drill bit (which must have lost all of its temper and started deformng down in the hole). We tried all manners of twisiting tools to grab onto the bit’s shank and try to loosen it even a little and there was NO budging it!

    Anyhow, to this day, that workpiece sits at eye level on my desk shelving, Written on the face of it, in bold black Sharpie is this advice: “ALWAYS use FULL RETRACT drill cycles on any hole deeper than 1inch !”

    That seemed to cure me – I’ve never mangled a drill bit since then.

  19. Karel says:

    It’s nice to see most people have a repertoire instead of a single incident :-) I can safely say “A lot of the above”, including sending lathe parts flying, putting fingers in rotating propellers and putting stuff in 220V wall sockets when I was young. I’ll mention the more exotic ones.

    Putting liquid nitrogen in 0.25 liter PET bottles is fun: it gives a nice boom, does not smell and does not leave residue (apart from strangely deformed pieces of plastic). We’d fill the bottle, close it with glue, and throw it outside. Within a minut they’d go boom due to pressure buildup. After scaling up to 1.5 liter bottles, nothing seemed to happen for a long time. There must be a leakage. Just after the decision had been made to recover the bottle (after ~10 min waiting) an enournous BOOM tought us to be more patient.

    Together with my brother I bought some small solid fuel rocket engines. We build our own rocket – not expecting it to fly high, we left out a parachute for safe recovery. The first launch: 3, 2, 1: Ignition! The rocket went up, made some strange turns and propelled itself into the ground 5 meters away. Seconds later, we heard a small ‘foomp’ – this was the SECOND stage of the rocket engine (which fires in the opposite direction), which is intended to break up a rocket to release the parachute. Instead, our rocket launched its own very hot engine, which landed less than a meter away from me and my brother. Lesson: distance is good, more distance is better.

    At work I made a load-lock for a vacuum chamber. It could bake out samples to remove the last bit of water, to minimize contamination of the UHV system. While testing one day, I bypassed the safety of the 2kW heater… and forgot about it. Some short time later, strange sounds from the chamber alarmed me… After cooling down the chamber, I found that the aluminum (600 degrees melting temperature…) sample holder and some other parts had melted together. It took me more than a whole day to take the load lock apart (sawing aluminum in an unaccesible place), before I could repair it. I won the ‘fail trophy’ that year. Lesson: never remove the safety. Or at least remember to put it back. In any case, write down if you removed the safety.

  20. Whew… Well, guess what… I got bit!!! I build Arduino DIY quad-copters and FPV drones and Oh man… did I get bit today…. Blood everywhere and just about passed out from the shock and the adrenalin hit!!

    I was trying to mess with the code in the Mega chip on the quadcopter with the props on in the Arduino configurator – I know STUPID, and I was in a hurry(double stupid) and was just gonna change one little thing in the code and then head back outside to test out my new FPV gear and BANG… It went full throttle on my desk, I blocked my face and slammed it down on the desk and it took about 1/4″ of my thumb as a tax… OUCH!!

    God saved me though big time, it shut off (I removed the auto off safety switch in the ESC’s when I re-flashed them with some custom code) so it turned its self off and then I unplugged it and delt with my thumb!!

    Anyway, be cautious out there gang… No matter how “quick” your fix is… Take some time and relax and do it by the book for safety. This was something that I had done a million times over the years and thought I had it done pat and I just didn’t want to take the time to do it the safe way… was in a hurry and shouldn’t have been. It cost me about 1/4″ of my thumb, which is healing up nicely but it could have been my life if that quad hit my neck or my eye sight had it hit my eyes; by the grace of God only. So… TAKE YOUR TIME out there and MAKE SURE you triple check before you rush to do something.

    PS- Quad is fine and back up and running just fine… Just a few broken props and a bit more blood on the electronics!! LOL

  21. Daniel L says:

    I blew myself up when I was 8 years old, 20 times in one night.

    I am now an engineer and one of the main people (2nd Tier or so) at the Makerspace, Artisan’s Asylum. I am a member of the Project Hexapod Project, maker of the Wifi-Deploying Node.JS Tank robot, and a graduate student at Northeastern University. Before that, I was a Local #3 Electrician in NYC.

    I grew up in an electrician’s household, and I held with great regard what my dad did. He was a 3rd generation electrician, and I was set to be a 4th generation electrician. So naturally, I wanted to try to be a big boy and do what dad was…..but without dad knowing, because he would stop me.

    I had a really cool closet, but there was no light in it. However, I there was a 2 foot long flourescent light fixture just sitting in a box in the garage. There was also, extremely conveniently, an outlet on the outside of the closet.

    So I waited for one night when my parents went to the movies, and I was left with the babysitter. Being the oldest, I assumed authority to do whatever I can’t do when mom and dad were home, because the babysitter would be stuck with my younger siblings.

    So, I proceded to mount the light fixture to the inside of my closet wall, grab some nomex cable from the garage, along with some wire nuts, a pair of linemans pliers, electrical tape, and a screw driver.

    I poked a hole on the inside of the closet to feed the nomex cable through, and I took the outlet cover, off, dismounted the outlet from the gem box, and removed the gem box from the wall, so I could grab the nomex cable. Remeber, I was 8 years old at this time.

    So I neatly routed the nomex cable into the gem box and remounted it in the wall, I then connected the other side to the ballast in the light fixture. So far all was OK.

    Then it hit me….and again….and again. I had never worked ‘live’ before, with the 120Vrms, or to put it another way, 342V peak to peak (because that is what the actual voltage variation inside your single phase outlet), present and ready to blast me with the first, and second, and third, wrong move.

    So I started to take the screw driver and remove the first wire. ZAP, through my chest, because I was holding the whole outlet in my right hand, and the shaft of the screwdriver on the hot with my left hand. Then I figured out that that hurts. I got the wire removed, but then the fun started. I kept shorting out everything and shocking myself through the chest or through the hand each time.

    My house was a Levitt House, with the old lightbulb-base fuses in the fuse box. The lights in my bedroom were also on the same circuit as the outlet, meaning that each time I managed to electrocute myself, the lights would go out, and I would be in darkness.

    So each time I electrocuted myself, I went down to my parents closet, and replaced the fuse I bew up. First replacing the 15A fuse with a 20A fuse, and then again after each time I electrocuted myself, a rate that increased because after each time I shocked myself my hands became more sweaty and conductive.

    I went through an entire box of fuses that night installing that light, unsupervised, Hacking house electricity, when I was 8 years old.

    I finally reinstalled the outlet, with the new wire tapping off the feed. I installed a light to the fixture, and it turned on. That was my first experience in hacking something and making it work.

    I then had to pretend I had no idea why there was an empty box of fuses, and I hid the light in my closet for about a year, before my mom found it. By then, statute of limitations for a elementary school kid had expired, and I was in the clear.

    1. Daniel L says:

      Also, just to show that I learned my lesson as a kid, when I was teaching an intro to robotics class at Artisan’s Asylum in March, I thought it was a good idea (or maybe just not a bad idea) to touch both ends with my left and right hands the end terminals that my friend, Joe. Sch. (see: Hexy Robot) created, connecting 50 9V batteries in series. I was speaking about internal resistance of batteries, and showed that it only flowed 0.5A when I shorted that array. Then I touched it and put 450V DC across my heart from 9V batteries.

      I am pretty sure I am an idiot.

  22. SkUrRiEr says:

    I had an old AT power supply and wanted to use it as a bench power supply, however it only produced 11.5 volts, not 12. So I had the brilliant idea of opening it up and seeing if there was anything I could fiddle with to get an extra half volt.

    Turns out that the fan, power connectors and a couple of other components were glued to one half of the case, while the main board was glued to the other, so it ended up sitting on the desk in a heap while I used my plastic handled jewlers’ screwdrivers (big chunk of plastic between me and the hot electric death? Safe!) to twiddle the trimpots. After some fiddling, I got it up to 11.8 volts.

    Then I decided to move it 10cm along the desk so I could reach something else. Grabbed both halves of the metal case in my hands and lifted it slightly to slide it across the desk. I got the biggest and most dangerous shock I’ve ever experienced, dropped it, yanked out the power cable, turned the switch off at the wall and swore off ever working on anything that may have mains power in it unless there was someone else in the house.

    1. Craig Couden says:

      Hi SkUrRiEr,

      My name is Craig with MAKE magazine. Great story! We are turning Mark’s post into an article for the magazine and would possibly like to include your story in the article. We’d like to include your name and location, so please email me at ccouden@makermedia.com to continue the conversation. Thanks!

  23. Chrisw says:

    I needed to drill a 1/2 inch hole in a 2″ thick 10 pound block of lead. I didn’t have a vise, but I figured if I used the slowest speed on the drill press, lots of cutting fluid and was very patient, it would be fine. About halfway in the bit seized and the whole block was wrenched from my hand and started spinning. Since the hole was not near the center, the tabletop DP started shaking violently and I couldn’t reach the switch. The power cord was plugged in directly behind the DP. Good thing the DP started walking to one side and I was able to finally unplug it.

    1. randomjnerd says:

      Lead is always gummy, grabby stuff. Its never failed to get stuck every time I have tried to drill it. Its great to turn, ok to saw, but it doesn’t like drill bits.

    2. Craig Couden says:

      Hi Chris,

      My name is Craig with MAKE magazine. Great story! We are turning Mark’s post into an article for the magazine and would possibly like to include your story in the article. We’d like to include your name and location, so please email me at ccouden@makermedia.com to continue the conversation. Thanks!

  24. […] we’ll just need to try and heed mark frauenfelder’s advice to not make them in the kitchen. […]