Makerspace Aluminum Casting Foundry

I arrived at the Makerspace on Thursday without an idea of what I would cast in metal, and in less than two hours I was removing my piece from the steaming petrobond! Check out the fruit of two hours of labor cast in metal!

That’s right! The Milwaukee Makerspace had its first (and second) aluminum pour on Thursday! Thanks to the hard work of several members, the Makerspace now has a fully functional aluminum casting foundry.  The custom built propane and diesel powered furnace melted an entire #16 crucible of aluminum in less than 20 minutes.  Check out Brant’s video to see our fearless foundry foreman leading the two pours!

To get the foundry running quickly, we’ve started out by using a lost-styrofoam casting method.  That is, styrofoam is carved into the desired shape and then a sprue and vents are attached with hot glue(!).  This assembly is placed in a wooden form, and is surrounded by tightly packed petrobond, an oil bonded, reusable sand.   Then, the molten aluminum is poured directly onto the styrofoam sprue.  The styrofoam is instantly vaporized by the 1250 degree Fahrenheit aluminum, which fills the void in the petrobond formerly occupied by the styrofoam. The air and perhaps even some of the styrofoam residue escapes from the mold through the vents.  We’ll be phasing in bonded sand and lost wax casting soon, so stay tuned for those details.

Eventually we’ll be having aluminum casting classes; however, we’re definitely going to be having aluminum pours on alternate Thursday evenings for the next few months.  Join our mailing list / google group to get more details.  Metal pours are spectacular to watch, so feel free to stop by to see the action around 7 or 8 pm, or join the Makerspace and participate!

Lasers + Whisky = Delightful Wedding Gift

One of our members got married yesterday, and I crafted a fine gift for him and his wife at the Makerspace.  The happy couple enjoys whisky, and I thought that providing a tour might be a nice idea.  The tour starts at inexpensive bourbon, moves through wheated whiskies, and on to rye. The tour continues in Scotland with some easy to enjoy Sherry cask finish bottlings, and then moves on to rare, Islay and finally mature bottlings (25 Year old Talisker!).

I found some old mohogany baseboard that had some aging varnish on one side and some old caulking on another.  After cutting two 18″ long sections, a few minutes of belt-sanding had them looking great.  I used a 1 1/4″ Forstner drill bit to bore 0.3″ deep pockets for the bottles to fit in.  I used one of our two laser cutters to etch the name/age/proof of each of the whisky sample on top, plus a congratulatory message on the reverse side.  To bring out the rich orangy-red mahogany color, I wiped on Beeswax / Mineral Oil .  Check it out close up, while imagining the symbolism of things getting better with age!

Arduino-Powered Surround Sound Synthesizer

The Makerspace Eight Speaker Super Surround Sound System(MESSSSS) has been supplying music to the Makerspace for quite a while now, but I identified a problem even before the system was fully installed.  Stereo recordings played back on two speakers are great if you’re in the “sweet spot.” If not, traditional approaches to 5.1 audio improve things, but all rely on there being a single “front of the room.” Unfortunately, it’s not clear which side of the 3000 square foot Makerspace shop is the front, and with four pairs of speakers in the room, even stereo imaging is difficult.

Fortunately, I’ve just completed the Makerspace Eight Speaker Super Surround Sound System’s Enveloping Surround Sound Synthesizer (MESSSSSESSS).  The MESSSSSESSS takes stereo recordings and distributes sound to the eight speakers in an entirely fair and user configurable way, thereby eliminating the need for a “front of the room.” Now listeners can be arbitrary distributed throughout a room, and can even be oriented in random directions, while still receiving an enveloping surround sound experience!

The MESSSSSESSS user interface is somewhat simpler than most surround sound processers, as it consists of only four switches and one knob.  Somewhat inspired by StrobeTV, the simplest mode references questionable quadraphonic recordings, in that the music travels sequentially from speaker to speaker, chasing around the room either clockwise or counterclockwise at a rate selected by the knob. With the flip of a switch, sound emanates from the eight speakers in a random order. Things get considerably less deterministic after flipping the Chaos Switch, adjusting the Chaos Knob, and entering Turbo Mode:  Its best to visit Milwaukee Makerspace to experience the madness for yourself.  I’m legally obligated to recommend first time listeners be seated for the experience.

The MESSSSSESSS is powered entirely by an Arduino Uno’s ATmega328 that was programmed with an Arduino and then plugged into a socket in a small, custom board that I designed and etched at the Makerspace.  The ATmega328 outputs can energize relays that either do or don’t pass the audio signal to the four stereo output jacks.  Care was taken to use diodes to clamp any voltage spikes that may be created as the relays switch, thus preventing damage to the ATmega328 outputs.

As shown by the minimal part count above, using the ATmega328 “off the Arduino” is quite easy:  Just connect pins 1 (The square one), 7 and 20 to 5 volts, and connect pins 8 and 22 to ground.  Then, add a 22uF cap and small bypass cap between power and ground, and a ceramic resonator to pins 19 and 20.  You can even use an old cellphone charger as the power supply.  Boom.  That’s it.  The real benefits of making your own boards are having a well integrated system, and cost, as the Atmel chip is $4.50 while a whole Arduino is $30.  Also visible in the photo are a programming header and the two ribbon cables that route all the signals to and from the board.

Audiophile Headphones

Sick of thin bass when listening to your favorite music over headphones? Missing that cinematic surround sound experience when you are on the go? Craving the visceral bass impact of live concerts? Trying to get to 11, but your headphones are stalled out at 6.283?  Move over anemic earbuds, there’s a new product in town: BIGheadphones: Bass Impact Gear’s new headphone product, available in two versions: Premium 5.1 (shown below in a user trial) and Mega Premium 7.2 (coming soon).

Reviewers are raging about the unprecedented dynamics, midrange clarity, and sound stage:

“Perhaps it was in the region of articulation and musical dynamics that this system impressed the most.  The dynamic bloom from soft to extremely loud was exquisite, and so clearly delineated that listeners could unravel musical phrases down into the concert hall’s noise floor and below.” The Audio Critic

“BIGheadphones speak with an organic integrity. They are hewn from the living woodendangered old growth Amazonian timber… I wept openly when forced to return the demo model.”– Stereophile

“BIGheadphones make critical listening a joy rather than a strain.  I was flabbergasted by their brilliant pitch certainty.  The midrange sounds were open, clear, and stunningly present. Playback performance like this makes use of the word transparent not only forgivable, but mandatory.” Audiophilia

“The 5.1 has an innate flair for speed and control that is incomparable. The command of bass dynamics moves beyond effortlessness to nonchalance. My eyeballs were vibrating! My hands are still shaking as I write this review.”Sound and Vision

“…the most important innovation in audio reproduction since the permanent magnet.”  –Acta Acustica

“W.O.W.”Bose listening panel

Reviewers agree that BIGheadphones are a huge leap in audio reproduction technology, larger than vacuum tubes, Stroh violins, carbon microphones and Edison cylinders combined.

Relative to planar speakers, typical box speakers are unable to develop the proper surface loudness or intensity typical of large instruments such as the piano.  This audio feat poses no challenge for BIGheadphones. Computationally modeled and optimized by a small and highly trained team of expert acoustical engineers over a period of 13 years, BIGheadphones were inspired by ingeniously thinking “inside the box,” not outside the box.  At the obsolete exterior listening position, a typical loudspeaker rarely generates even a realistic classical music concert level, but inside that same speaker, the sound pressure levels can quite easily exceed the 115 dB of a stadium rock concert. This realization was the BIG breakthrough, but was only the beginning of the struggle pursued by our elite acoustical research team.  Our uberengineers had to break the chains of common design practice to breathe the refreshing mountain air of inside-the-box acoustics, where nearly everything is inverted.

To illustrate, achieving loud bass external to a speaker typically requires the box be a very large size.  However, inside the box, the bass response is naturally flat to the lowest frequencies, and the smaller the box the louder and more impactful it becomes. Further, our astute engineers shrewdly realized that the stop-band and pass-band inside and outside the box are also opposite, as illustrated in the enlightening plot below of the subwoofer section of BIGheadphones. The Blue curve shows the hyposonic level inside, extending well below 10 infrasonic Hz, while the Red curve shows the meager sound pressure level in the more traditional listening position two meters in front of them.  Notice how the passband outside the box begins at 2kHz, whereas the passband inside the box ends at 2 kHz.  How many other speaker systems can boast of a subwoofer response that is flat over more than three orders of magnitude?  Now that’s innovation!  And this is just the customer-average response—the bigger your head the broader the bandwidth that you can brag about to your audiophile friends.

The observant reader has already noticed that this plot shows BIGheadphone’s output level is a mere 142 dB – only 22 dB above the threshold of pain.  Note though that this is with a paltry 1 Watt input – in reality, they are capable of 17 dB higher output with the optional high output amplifier add-on kit, though this reduces the playback time to under 36 hours per charge.  And that’s just the subwoofer!  The industry-leading, consciousness-altering bass response shown above is augmented by five horn loaded, carbon fiber reinforced porcelain dome, 2” diameter neodymium tweeters with single crystal silver edge wound voice coils.  With this critical addition, the frequency response of the BIGheadphones extends from below 10 Hz to 31 kHz and beyond!  Get your BIGheadphone audition today at your local Hi-Fi retailer!  “BIGheadphones, the last audible note in audio reproduction!”

(Not available in France.)

Thanks to the editors at RSW, Inc.