Steel Rails double-slit build for IQC == win!

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Over the last 5 weeks,…

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my brother from the very same mother, Dave White, and I designed and…

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a human-scale version of the classic quantum physics double-slit experiment for the Steel Rails Sessions event.  Participants would be the light and by passing through the slits their images would be captured and projected up on the screen, illustrating the dual particle-wave nature of light.

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Over sushi lunch, back in May, Hilary asked “Would makebright like to do an installation for Steel Rails?” and I immediately responded “Yes, please!” because Steel Rails is the coolest homegrown cirque-du-soleil cross-disciplinary surreal mash-up good time going.  And y’all know how I’m always saying if you like what you see: contribute!  I was doubly enthusiastic when she told me we would be paired with sponsor…

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the fabulous Institute for Quantum Computing (IQC).  Martin Laforest, Manager of Scientific Outreach at IQC, here schooling Dave on all things quantum, and…

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Colin Hunter (right), Communications Specialist at IQC, met up with Dave and I for beers and brainstorming at the Huether.  (BTW, nice blog post on the event, Colin) I drew out IQC’s goals for participating, which included raising community awareness of IQC and “taking back the word ‘quantum’”.  We all wanted something interactive, and Martin and Colin pitched the double-slit experiment as a good candidate subject for the installation.  Fairly well-known and accessible, it was one of the subjects Dave and I had discussed in prep for this meeting while working our Loud Monkey installation at the Toronto Maker Faire the previous weekend.  And from our Maker Faire experience we learned simple == good.  I had a rough idea of the logical blocks for a design, but…


it really takes doing up some proof-of-concepts to see if it is all feasible given project constraints.  Here’s a trial circuit of a Parallax passive infrared proximity sensor (top) that we ended up using to detect people in the slits.  Like lots of parts in the make-o-sphere, this one turned out to not work quite as advertised: when triggered at close range (as in our application: ~8-16” from subject) the sensor output tended to oscillate a bit before settling down.  Not ideal.  After exploring some extra power-conditioning circuitry, in vain, it turned out that mechanically attenuating the IR heat signals from participants with an aluminum foil aperture was just the ticket.  The Arduino Uno + prototype shield (bottom) was the glue that would link the sensor to the laptop over a USB virtual serial port.  The MSCOMM ActiveX control on the laptop brought its own kind of voodoo to the design, but we worked that out too.  For image capture I had originally wanted to use second-hand tethered Canon PowerShot cameras, but that would have blown the budget, so I settled for $15 web cams.  Web cam performance in low light required some custom and very bright white LED lights to illuminate participants.  It was a good tradeoff.


Recalling the problems CAFKA had running their digital projector on the train at last year’s event, I researched some solutions for…


stand-alone power.  But going this route would have doubled the small budget, so we did our due diligence by…


visiting the train yard well before the event, with all our electronics gear in tow, and running some tests on train generator power.

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It all checked out, so we moved on to…


pricing out a whole whack of ABS fittings and…

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pipe, that would make up the frame for the slits (needed a material cost list for the project proposal).  ABS Advantages: strong, lightweight, fairly cost-effective.  Disadvantages…

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You gotta cut and…

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glue all these parts together with a welding solvent glue that gives you about 7 seconds of working time.  Need to be very deliberate when doing this part.

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And before we glued, we took the dry-fit frame to the train yard to make sure we could get it through the door once it was welded together forever.

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The venue gave us lots of good challenges to work on: space being a big one.  We only had 8 feet across the car to work with and 7’3” to the ceiling.  The limited space posed challenges to moving people through and around the installation and it also made it tough to stabilize the structure.  Fortunately we were allowed to screw the bottom pipes to the floor.  At the top we used compression-fit pipes across the car.  It was plenty sturdy.

We even fabbed our own projection screen so projected images could be seen on both the front and back of the screen.  The original design had the projector mounted on top of the slits, but that just seemed like inviting disaster when we considered the moving train and drinking participants, so it got relocated and strapped down to a very securely fastened milk crate stand at the side of the car.

My vision of using fabric panels on the slit frames really looked great, though I didn’t consider it would take me about 22 hours of cutting and sewing (and 4 calls to my Mom for expert advice) to complete them.  I’m a lot better at sewing now than when I started this project.  Sewing 10 yards of velcro on is harder than you think.

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On game day, the installation looked good, held up, and most importantly: worked.  Jacqui Murphy (right) fearlessly emerges from the experiment.

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Evan, a Master student with IQC, was awesome at demo’ing the actual experiment with a laser and some lab gear for dozens of curious visitors.  Thanks Evan!

And thanks to:

the makebright support team – you know who you are

IQC – for sponsoring and being really great collaborators

Hilary Abel – for dreaming up Steel Rails and trusting us to contribute

Neal Moogk-Soulis, Brian Craus, Danny, Darren, and all the train guys – for helping us work out our venue challenges.

Some great discoveries:

Sherwood Systems on Ottawa St. was *awesome* for projector rental ($50/day).  Great price/availability/service.

Essential Image, Tony Tuka’s company on Gage Ave is where I had my posterboard printed directly on to foamcore on their giant 4’x8’ inkjet printer.  Tony was super helpful speeding my job along and really generous in explaining the rig.

Len’s Mill on Moore St, a local textile institution here, was *awesome* for helping me sort out what fabric would be best for the project and they answer all sewing questions.

Solarbotics is a great Canadian company that is a super place to buy sensors, Arduinos, shields, and other electronic bits.

Then it was on to the fun…

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Rails and nails.

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Hi Jenn Carreiro, Hilary’s right hand event planner for Steel Rails.

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Killer set by Vacuity at the train shed in St. Jacob’s.

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My pals, and kick-ass artists: Jennifer Bedford and Gareth Lichty of CAFKA.  Hey, and there’s Sarah Kernohan in the background.  All three of these makers have been speakers at my 5+5 events.

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Neal Moogk-Soulis, my train liaison extraordinaire.

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Just met Dan Silvestru of Startup-Drinks that night and later saw his drawing of harmony.

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Good to catch up with artist David Hoover who designed these dope shirts.

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Artist Melissa Doherty hanging with Karl Allen-Muncey and Amy Vandenberg of CuteGecko.  These three work along the power hallway at The Tannery.

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Yeah, that’s what I’m talkin’ about!  Stephen Preece of The Jazz Room did a great write-up in the paper about the event.  Can hardly wait for the fall opening of The Jazz Room.

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Great to hear jazz in front of The Clay & Glass for the after-party.

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No rain!  Sweet.

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More cool art inside, plus…

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Dave, clapping vigorously.

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We put the ‘D’ in…

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no, not “desire”, but in design and deliver.

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That’s a wrap…

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on our first sponsored gig.

Happy making,


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