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Reflect-O-Scope

The Reflect-O-Scope was an interactive museum exhibit I worked on a few years ago. It was a fantastical machine that allows users (typically children) to slide materials under a microscope and examine them. The materials were from the sponsor of the exhibit and consisted of specialty tape materials adhered to plastic boards.

One of the original ideas was to allow for focusing, but that got scrapped. We figured kids would put almost anything under a microscope, their hand, their little sister, etc. Focusing meant a moving mechanism, and it was deemed to complex at the time.

The sculptural build was done by John McGeen and Austin Boechler. My focus was on the hardware and software. There’s a USB microscope connected to a computer and then a small HDMI display in the “goggle” shaped piece that the user looks into. It’s all a bit “periscope” like in design.

The original design also had a secondary monitor (a large TV) that would be mounted further away, so people could see weird things on the TV and it would draw them over. Lots of features got killed due to lack of time or other reasons. Most of what you see on a museum floor probably started out a lot more complex when originally designed, and then simplified as time goes on.

I wrote the software, which is just an application written in Processing that automagically launches at boot up, runs full screen, and shows the output from the USB microscope. There’s also a companion application called “List Cameras” that can display all the connected USB cameras and all of the possible resolutions they support. This is there in case the USB microscope ever needs to get replace. The exhibit tech just needs to run the application and then edit a config file. No recompiling of the application is necessary.

One more fun addition was a white plastic tube running along the outside with some NeoPixels in it featuring some funky color runs to add to the fantastical nature of the piece.

One of the nice things about this component was that the software was created in-house, so the component could be replicated easily without additional license fees. (We had an amazing software partner we used for the complex things, but simple stuff was done, when possible, in-house by the tech team, which was basically me.)

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Velocity Exhibit

Velocity_Loop_5507

You may have already seen John’s post about our Velocity exhibit, and I must say, he did an amazing job with all of the CAD and CNC work to build it.

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For my part, I handled the technology that went into the exhibit. (Which sadly, you can’t see much of in these photos because some were shot after things were powered down.) For three of the five components, I spec’d the hardware and worked with a software developer to upgrade the old version of the software to something more modern, stable, and easier to calibrate and support.

Velocity_CK_5525

I can’t even tell you how many golf balls I rolled down all of those ramps. At one point we had an issue with a projector overheating and I set up a time lapse camera to run all day and overnight to give us some idea how long it was staying on before shutting off. We eventually fixed it by adding a duct to the projector housing to draw the heat out and away. We’ve used earlier models of this projector with no issue, but this is why we do extensive testing… you never know what problems are going to pop up.

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If this exhibit looks familiar (!?) it might be because there are now three copies/versions of it. Besides this one which was a “for sale” item, we’ve got two on the road, one of which will be returning to the Betty Brinn Museum this summer.

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By the way, if you occasionally have a bunch of old golf balls you want to get rid of, let me know… There’s a non-profit in Milwaukee who would love to take them off your hands. ;)

Velocity_Roller_Coaster_Lazy_River_5517

Velocity_Jump_5499

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Prototyping a bunch of knobs…

knob-rot

If you’ve ever used a potentiometer you know it can only turn so far. About 270 degrees of rotation is what you get out of most potentiometers, which is plenty. The problem with using potentiometers in museum exhibits is that while adults (typically) know that when the knob stops turning you should stop turning the knob, kids don’t always know this. Kids are notorious for going too far when it comes to physical controls.

pieces-stacked

So I’ve been working on a way to use potentiometers in an exhibit, but hide them down below in the cabinet, and expose a control knob to the surface that has limited rotation. About 220 degrees of rotation. I could do more, but the idea of using less than 270 is the key. If we don’t get too close to the beginning or end of the rotation limit, we should be able to prevent the potentiometer from being twisted too far and becoming damaged.

pieces-all

I drew up the parts needed to build an encased knob with a hard stop inside. In the final version the knob will be machined from HDPE plastic using a CNC router. I opted to 3D print the pieces for the prototype because it was quick and easy. (“Quick” is relative, of course, but I finished up the drawing and got the model printing at the end of the day, so the printer did the work overnight while I wasn’t there.)

pieces-3d

I drew all the pieces in Inkscape and then exported DXF files and brought them into OpenSCAD and extruded them to 1/4″ high. There’s a 1/4″ hole in a few pieces (and a slightly larger hole in the bottom piece) so that a 1/4″ steel shaft can be inserted. The shaft will be connected to the potentiometer. (I made a 3D printed prototype of that too, which you can see here and here.)

pieces-exploded

Here’s an exploded view of the assembly. Sometimes it’s tricky to design things like this using flat 2D shapes in Inkscape, but I’ve gotten used to it, and I think I’m pretty good at it. I should mention I also printed a paper prototype to help figure things out along the way. (And yes, the original plan was to laser cut the pieces out of foam core which would have made the most sense, but the laser cutter was not available when I did this.) The fact that I created 3D models did allow me to make the nice exploded view very easily.

pieces-stacked-orange

Here’s a quick assembly using hot glue. Just to test how it worked, as well as get a feel for the size of it. (I’ll have a follow-up post about the layout of the whole panel.)

knob-together

HDPE can’t really be glued, so we use screws (hidden when possible) to attach layers. We may be able to get away with fewer layers than I used here, because I used 1/4″ layers, but it might make sense to use 1/2″ or 3/4″ layers since we often get HDPE in those thicknesses. And of course we can pocket things out, and not just use a flat stack. (Again, this is a prototype.)

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Durability… for the children!

Durability

On the durability scale it goes from “Consumer” to “Commercial” to “Industrial” and then finally to “Children’s Museum”.

While most adults can figured out how things work, and most will actually use things the way they are designed to work, children will use things every way possible, not (usually) maliciously, but because the are still figuring things out. Install a lever that goes up and down, and they’ll move it up and down with all the force their small bodies can muster, so you might want to add some hard stops on the inside.

Controls

Kids also can’t read/don’t read (to be fair, many adults don’t read either) so add some arrows showing direction of movement. Also if those arrows are just vinyl you applied to the surface, they’ll get peeled off. Every interaction needs to be thought about in great detail, and sometimes you need to think like an angry vandal hell-bent on destroying things.

Plan for things to break, because they will, but make them easy to maintain and repair. Use off-the-shelf parts when you can, so replacements are easy, or if you fabricate the parts yourself, make spares, and document how to make more spares in the future. Use Loctite. Use set screws. Use Loctite on set screws. Use hot glue. Use lots of hot glue. Use screws and bolts, not nails and staples. Make sure you can take it apart and repair it.

Stay Durable, Friends!