Experiment 41: Growing Sulfur Crystals

In this experiment, I recrystallized garden sulfur (90% pure) to make pure sulfur crystals that gleam in the light and are a light yellow color.  First, I acquired a solvent for sulfur.  Since sulfur dissolves well in toluene, xylene, and carbon disulfide, I picked the most common option--xylene.  My xylene came from paint thinner (it listed xylene as an component).  To separate the xylene from the methanol and acetone also in the paint thinner, I mixed equal volumes of water and paint thinner and vigorously shook.  This should be done outside, as the vapors are unhealthy.  I poured the mixture into a graduated cylinder and let it settle for 15 minutes.  The xylene, which is insoluble in water, floated at the top, while the acetone and methanol remained in the water layer.  I syringed off the xylene and ended up with ~45mL from three 50mL batches of paint thinner.

Then, with my solvent collected, I began the recrystallization.  I placed the xylene in a beaker with a stir bar and some impure sulfur and heated it on medium heat on my hotplate.  I also had a beaker full of snow water resting on top of the xylene beaker to act as a crude condenser and recover xylene vapors.  The whole experiment was done outside.  The xylene shouldn't boil, or else vapors will go everywhere and escape the crude condenser setup in large quantities (unhealthy).

With the sulfur dissolving, I placed another beaker with a small amount of xylene (no sulfur) on the hotplate to warm.  I also put a third clean beaker on the hotplate with a coffee filter on its top.  Just as the xylene began to boil, I poured the prewarmed pure xylene through the filter in the third beaker.  This warmed the filter and the beaker to prevent sulfur from crystallizing immediately on contact with the cold surfaces.  Then, I filtered the dissolved sulfur mixture through the filter.

Once it finished filtering, I removed the filter and covered the beaker's mouth with tape to prevent losing xylene vapors.  I then wrapped the hot beaker in towels to slow its cooling.  This helped the crystals to grow more slowly, which makes bigger crystals.  Once it cooled completely, I decanted off the xylene (which still had some dissolved sulfur in it) and scraped the sulfur crystals onto a coffee filter to dry.  After the first batch was dry, I tried using them as seed crystals for a second and third batch of crystals, which seemed to make larger, prettier crystals.  The resulting pure, shiny piles of sulfur crystals were quite beautiful.

Experiment 40: Glowing Xenon Plasma Tubes!

This experiment came about completely by chance.  When playing with my Whimshurst machine from Experiment 30: Miniature Wimshurst Machine and the small xenon flash tubes from the disposable cameras I disassembled in Experiment 39: Electromagnetic Coilgun, I discovered that the static electricity made an extremely brief flash in the tube.  Intrigued, I connected the flash tube to a 10Mohm ballasted high voltage power supply and discovered that the tube lit up!  The xenon stayed excited and hosted weird bouncing blue-white arcs!  I was amazed!  After quite extensive experimentation, I observed some interesting behaviors.  For example, when connected in series with a small arc gap, the xenon tube's jagged, jiggling arcs changed to a single soft, stationary arc.  I also noticed that touching the outside of the glass tube with a bare finger caused the arcs inside to become smaller and more numerous, as well as more active in their bouncing.  After a while, I decided to make a light-up periodic table specimen of xenon.  I had to get another high voltage supply since the one I originally used was for another project, so I used the CCFL inverter from an old LCD monitor.

After removing the cover of the monitor, I turned it on and probed the inverter board with my multimeter (I identified it based on its "WARNING: High Voltage" label).  I gathered enough information from the voltage readings of the input of the board to identify +12V and GND.  A search of the part number online turned up a datasheet which identified the dimming (0-5V) and on/off (+3V/0V) pins.  Using my ATX lab power supply, I was able to make the fluorescent tube of the monitor turn on at my command.  I used a LM317 voltage regulator circuit to provide a variable voltage to the dimming pin, which controls the current flow and thus the lamp brightness.  I then connected my xenon tube between one of the high voltage outputs and the return on the inverter and tested the setup.  It worked!  With more current, the xenon tube's sharp, jagged arcs changed to an odd sine wave shape with smoother corners.  This made the tube run hot, though, so I ended up using a lower current setting.

During this process, I accidentally discovered that holding a neon or xenon bulb (finger touching glass) near the high voltage caused an arc to jump from the high voltage wire to the electrode of the tube and also made a soft, pleasant glow inside the tube.  I loved this effect and, after many frustrating failed attempts to reliably replicate it, found a solution.  After reading up on how camera flashes work, I learned that a high positive voltage applied to the glass outside of the tube ionizes the gas inside, allowing current to flow and make the blinding white arc.  I tried connecting a camera flash's ionization wire to the high voltage, and with an electrode connected to the return, I got the amazing soft glow!  It wasn't very uniform, though, so I experimented more and found that connecting both electrodes to the return helped the uniformity.

To make the periodic table display, I wound a fine wire around one of my smaller xenon tubes and epoxied the ends in place.  This was my ionization electrode.  I cut a small wood base to fit in my periodic table and made some copper frame wires to hold three xenon tubes in place.  Then, I soldered one large xenon tube to be in an arcing configuration and two other tubes to be in an ionized glow configuration.  These I connected to the inverter so that the glowing tubes shared one high voltage output and the arcing tube got an output to itself.  Since my periodic table wasn't near any outlets, I used eight AA batteries in two 4xAA packs to power the inveter and LM317.  After installation, I was extremely happy with the blue-white light emanating from my Xe periodic table cubby.  Though the project took a long time to complete, I am glad I saw it through.  Noble gases are pretty, aren't they?

Experiment 39: Electromagnetic Coilgun!

Like the ball mill, this is another project I've been working on for some time.  After being inspired by a friend, I decided that I absolutely had to have one of these delightful toys.  In principle, a coilgun works by using a coil (duh!) to create a strong magnetic field which pulls a ferrous projectile forward.  As the projectile enters the center of the coil windings, the coil turns off, releasing the projectile on its deadly flight.

To store the energy for the intense magnetic field, I used 17 disposable camera capacitors arranged in parallel.  These capacitors are charged by four identical camera capacitor charger circuits whose outputs are wired in parallel to the capacitor bank.  The inputs to the chargers are wired in parallel to a normal-duty switch, which connects the charger inputs to four AA batteries, also in parallel.  All this parallel-ness makes the capacitors charge faster and lets them dump more power all at once into the coil.

The "trigger" for this coilgun is a heavy-duty (20 amp/250VAC) switch wired between the coil and the capacitor bank.  While this setup works decently well, I have noticed that the switch contacts occasionally weld themselves together from the massive (possibly lethal) amounts of electricity being flung across them.  I may fix this at a later date with a better solution.

To make the coil, I took ~90 feet of 30AWG wire from a microwave oven transformer secondary/high voltage winding.  I cut this in half and twisted the ends together to make two strands in parallel.  I then wound this around a pen tube with two acrylic end stops 30mm apart from each other.  I did 10 layers this way before sealing the wires tightly in place with hot glue.  The coil began 30mm from the frontmost part of the end cap of the pen.

The projectiles I am using are 30mm sections of 1/4-20 bolts and 30mm sections of 6mm steel rod.  They work really well and are cheap.  I placed some of them in a copper sulfate bath (after a brief cleaning dip in 25% H2SO4 and then in aqueous NaOH) and then polished them to give them a shiny copper plating, which adds to the "authentic bullet look."
As you can see from the video, it's a pretty fun toy!  To wrap up the project, I did a test measuring the projectile drop in altitude versus the distance of the shot to calculate the muzzle velocity.  As it turns out, this gun has a 12 m/s muzzle velocity with a 7g steel bullet.  The bullet then has a kinetic energy of 0.5 joule.  *Sigh*  Ah - it's still fun even if it's weaker than a BB gun.

Experiment 38: Iron Thermite!

After years of anticipation, I finally succeeded in making iron thermite, the king of infernos!  I used the aluminum powder from Experiment 35: Ball Mill & Aluminum Powder for Thermite and the iron (III) oxide from Experiment 37: Making Iron (III) Oxide for Thermite mixed intimately in a 1:3 mass ratio.  The resulting mixture was a somewhat golden color and had the consistency of flour.  I placed the powder in a depression dug in a pan of sand and lit it with a 2" magnesium ribbon.  The reaction exceeded my wildest expectations - it was an utterly brilliant ball of orange flame, totally engulfing the pan with its furious power.  Check out the video below for footage of the event:


Also, I have now started a Summer of Thermite playlist on YouTube, so be sure to subscribe to my blog by email or to my channel via YouTube to keep up with these firey experiments.  I plan on doing many more reactions similar to this one.

After the slag cooled, I removed it from the sand and broke it into fine pieces using a hammer.  For the most part, it was bubble-filled glassy alumina that easily fractured.  In some pieces, I found small blobs of iron produced by the reaction.  I cleaned the black oxide off the pieces of iron using vinegar and then swished them around with sand to abrade off other surface contaminants.  After weight the resulting product, I was absolutely astonished to find out that I had only recovered 16 grams of iron from the reaction!  Without even calculating anything, that is a terrible yield, considering I converted over 200 grams of iron in my iron (III) oxid
e producttion.  But since I like chemistry, I did some simple stoichiometry to reveal that starting with 322 grams iron (III) oxide, the theoretical yield would be 225 grams iron metal, so I got a 7% yield.  I believe most of my iron flew up during the reaction and rained down to earth as tiny iron droplets.  Honestly, though, the yield is of little concern to me considering how exciting the reaction was.  :)

Experiment 37: Making Iron (III) Oxide for Thermite

In the last experiment, I made fine aluminum powder, with the intention of doing the thermite reaction.  The most common type of thermite is the iron thermite, and its second ingredient is iron oxide.  Both red and black iron oxide will work, but I used red (iron (III) oxide), because it was the most common and I saw good instructions on making it.  Basically, the process involves running electricity through iron electrodes in a brine electrolyte until one electrode is completely eroded away.  This produces rust from the iron.  I switched the polarity (+12V and ground) of my electrodes every 12 hours to even out the erosion and make the cell last longer.  After 36 hours, I drained the excess water and baked the sludge at 400°F for an hour.  I then ball milled the product to a fine powder.  I also made a video showing the system I developed of making red iron oxide in large amounts (it works quite well):

Update to Experiment 7: ATX Computer Power Supply Conversion

Although blowing up hydroxy-filled bags and creating shotgun-level bangs was fun, the end result of the last experiment was that I burnt out my lab power supply.  To remedy this situation, I acquired another ATX PSU from a friend and converted it, this time with some added flair.

Previously, I used two packs of overpriced binding posts from RadioShack.  Each pack had one red and one black, which meant that for three positive voltages I either had to buy even three packs or just use a black post where a red one should have gone.  I opted to use a black binding post where a red one should have gone in the +5V terminal.  That didn't look good, so this time around I found an online supplier and exactly what I needed.

I had also previously broken a blade of the fan on my lab power supply.  The fan was on top as there was no space left inside the unit.  However, I didn't have extra screws for the fan cover, so I left it off, and a fan blade got broken.  For my second lab power supply, I reused four screws from the broken unit to attach the fan cover, which gave the supply a nice shiny finish.

Lessons learned from destroying and rebuilding my lab PSU: 
  • Don't try to trick the overcurrent protection on an ATX PSU - it's there for a reason.
  • Source parts online - it's cheaper (sometimes free) and has better selection that RadioShack.
  • Using social connections to obtain unwanted (but useful) parts can pay off handsomely - the PSU I previously bought for $20 was free the second time around.

Experiment 36: Hydroxy Gas Fun

A very, very long time ago, I found a cool YouTube video (this is how everything starts, right?) showing a hydroxy torch melting stuff.  Hydroxy torches are pretty neat, because they burn H2 and O2 gas cleanly, only producing water and a whole lot of heat.  The heart of the hydroxy torch is a hydroxy generator, which electrolyzes water to split it into its constituent gases.  I tried making one with hot glue and some scrap metal, and it failed about as badly as the word "hot glue" signifies.  Hot glue is an inferior building material.

Years later, I was inspired to work on the project again when I saw a friend's hydroxy generator that he bought off eBay.  I used the same scrap metal from the first generator design, but this time I used some proper plastic rods with spacers to assemble my electrolysis plates.  This time, the design worked beautifully!  I demonstrated that the generator worked by filling various containers with the explosive hydroxy gas and igniting them with a remote match.  The video below has a compilation of some of the best explosions:
Regrettably, I seem to have burnt out my lab power supply (Experiment 7: ATX Computer Power Supply Conversion), so I'll have to make a new one and be more careful with my current consumption.  Perhaps after that, I will use the hydroxy gas for a torch, but as of now, I am extremely happy with my newfound source of earth-shattering explosions.  :)

Experiment 35: Ball Mill & Aluminum Powder for Thermite

Years and years ago, I decided I wanted to make thermite, so I tried to make a ball mill for producing aluminum powder, a key ingredient of most thermites.  A ball mill powderizes materials by crushing them with the continual falling action of hard milling balls (in my case steel ball bearings).  My first attempts to build a ball mill failed horribly.  They were slow, finnicky, and didn't work at all.  A couple months and a few YouTube videos later, I built one using a corded drill and some castor wheels, along with a metal container.  The attachment of the drill to the container lid was so stressful that I ripped a perfect circle out of the container lid.  I then switched to a plastic container with small bars on the inside to lift the balls up and send them crashing down on the aluminum foil inside.  This worked... until the drill melted.  No joke, the plastic on the drill melted and that was the end of the drill.  Oops.

A few more months went by, and then I got a free dryer off Craigslist.  The motor worked well, even though the first attempts to use it didn't.  One time the motor spun so fast the ball mill container flew off toward the ceiling!  I finally figured out a way to harness the speed of the motor with some belts and wheels to tame its ferocity.  However, the ball mill still had the small bars on the inside.  Most ball mills don't have these, for good reasons - they are loud and hard to clean (especially when attached with duct tape!).  So, I took them off, and the balls in the mill proceeded to slide, rather than tumble.  After a few more months of apathetically looking at the years-long failed project, I finally got the motivation to finish it and found a container that I hoped was the right size - the balls filled it approximately halfway up.  To my extreme surprise, the ball mill worked!  After years of dissapointment and failed prototypes, the mill jar finally opened to reveal ultra-fine aluminum powder!  This is how many things in the inventing/experimenting business go. They take perseverance and dedication to finish and might not be immediately rewarding, but they will pay off if you finish strong and pull through until the end.
This has been the too-long story of how I built the ball mill to finally fulfill my dream of thermite.  It takes about a week for it to turn foil shreds into fine powder.  The aluminum powder produced has been confirmed to work in thermite.  To sum up the mill's actual operation, I made the above video explaining how it works for milling aluminum... or anything else highly flammable.  :)

“I have not failed. I've just found 10,000 ways that won't work.”
― Thomas A. Edison

Experiment 34: DIY Metal Stamping

A while ago, I found myself wanting a good way to make metal stamps for stamping element symbols into the various pieces of metal I have, in order to identify them when the time came to melt them into new and interesting objects.  To accomplish this, I used a steel bolt and the electro-etching process to make a neat little stamp for hammering into metal.  I first sanded the head of a bolt so it was flat and almost mirror-like in finish.  Then, I applied masking tape and used a box cutter (along with a strong light) to painstakingly cut away the design, flipped in reverse.  Since it's reversed, it will stamp out in the right direction.  I then attached the bolt to my power supply's +12V and hooked another wire up to the ground terminal.  I then placed the ground wire in the bottom of a dish with about 1/2" of strong salt water and put a cotton ball on top of it's exposed metal strands.  I pressed the bolt head onto this lightly and waited about 10 minutes.  What happens is the electricity erodes the exposed areas of the positive anode, producing iron oxide.  This darkens the brine solution.  After about 10 minutes of etching, I rinsed off the bolt and peeled off the tape.  The places under the tape were still shiny, but the exposed areas had eroded away considerably and were deeper than the lettering, as seen above.

Finally, although it might not have been necessary, I hardened and tempered the stamp.  This will prevent undue wear of the stamp, since it will undergo a lot of force throughout its life.  I used a propane torch to heat the stamp head bright orange and then quickly dropped it in room-temperature water.  To relieve the stresses built up by the sudden change in temperature, I tempered the stamp by heating its entirety to a blue color and then letting it cool in air.  After testing on a strip of metal, I was quite pleased with the result.  Honestly, I didn't think it would turn out this well.

Random Afternoon Project: The Coin Sorting Machine

This is what happens when I get bored on a summer afternoon.  After being inspired by a recent Instructables project showing how to make a coin sorting machine, I built my own, changing a few things (for example, this sorts U.S. currency instead of Phillipine currency) and adding a silly name laser-engraved into the front.









The machine uses gravity and a slight backward tilt of the front window assembly to sort coins using specially-sized windows cut into the cardboard.  The coins want to fall backwards, so when they get to the right window, they drop off the ramp, thus ensuring that they don't fall into a larger window farther down on the ramp.

I also engraved the name "Moolah Masta 3000" and some icons into the front of the sorter using my laser cutter.  I have a category of posts related to building the laser cutter and fixing the issues that sprang up with its scavenged parts.

So far, the soin sorter hasn't every mis-sorted coins or gotten them awkwardly stuck.  For having no moving parts, it works surprisingly well!
Subscribe to: Posts (Atom)