so we’ve got this play running right now in which (spoiler alert!) a huge comet hits the earth about 1/3 of the way into the show. nearly all forms of life are obliterated, with the exception of our heros, who are safely tucked in a biolab-cum-bomb shelter underground.
hilarity ensues.
at the moment of impact, even underground, there’s some considerable dust, shaking, rattling of cupboards, and so forth. a critic for SFGate wanted to know how we did all the stage tricks — making a cupboard swing down off the wall, a ceiling panel crashes in, boxes come tumbling down, and so forth. our PR manager asked me if i’d answer the reporter’s questions about how some of the specific tricks worked.
i really tried to be succinct. i did. but when you ask someone in the trenches how things work, well, be prepared for the long answer. sadly, an hour’s worth of email got boiled down to what essentially amounts to: “they used extra lumber and some magnets.” to wit:
what i wrote (it’s seriously okay to skim):
The dropping cabinet —
The dropping cabinet effect had to be taken into account pretty much every step in the design and build process, from analyzing and pricing out the set plans, construction methods and materials, to designing the sequence of cues for the Boom and staging the actors.
Both the upstage wall and the cabinet had to be constructed differently to be able withstand the 8″ drop nightly. The entire wall had to built out of heavier, sturdier lumber than what you’d typically use for a standard theatrical flat. The cabinet, too, was constructed from a steel frame skinned with 3/4″ plywood, then a layer of masonite, brackets in all the corners to help it stay square under the stress of the fall. The cabinet alone weighs about 400 lbs.
Hanging it on the wall was tricky, also — the bottom right corner is a pivot point that allows the cabinet to rotate. The top left corner of the cabinet is a peg that runs through the wall in a curved slot — the top of the slot is where the cabinet sets in its upright position, the bottom of the slot is where the cabinet rests once gravity has had its way. Calculating the path that the cabinet would take as it rotated on its pivot point required some geometry. The other two corners of the cabinet don’t attach to the wall at all — they couldn’t, for the cabinet to be able to swing — so the cabinet has to hang on the wall with only two attachment points. That was one reason for the rigid steel frame construction.
Behind the scenes, on the upstage side of the wall, the upper left corner of the cabinet (the side that drops) is held up with a big electromagnet suspended from the lighting grid above the stage. The magnet we used was rated to hold up to 1400 lbs. It’s a disc about 5″ in diameter. When turned on, it sits flat against a steel plate welded to the back of the cabinet. Our Master Electrician had to rewire the electromagnet to work with the theatre’s lighting system so that it could be controlled by the lighting board (rather than plugged in with an extension cord).
When the moment for the drop comes, the magnet is turned off (there’s a loud clunk sound that comes from the magnet itself — fortunately not a sound that needed to be masked given all the other loud sound cues happening at the same moment) and the cabinet drops 8″ to its bottom resting point.
Inside the cabinet, all the stuff — the boxes of batteries, cliff bars, bottles of bourbon, diapers, etc — had to be glued down inside the cabinet so that when it falls, they don’t roll out. The bottles of bourbon were created from plastic, rather than glass, for safety reasons and also to cut down on how much weight went into the already-very-heavy cabinet.
How the timing works —
Because we’re using an electromagnet, we were able to connect and control the magnet with the light board. Which means that turning off the magnet was simply written into a lighting cue. That way we had very detailed control over the timing of the cabinet drop. The Stage Manager calls the series of light and sound cues that make up the sequence of the Boom to the Board Operator, who runs the light board and the sound computer (which in turn controls the analog sound board). So the light cue was written to turn off the magnet at the exact moment we wanted the cabinet to drop in the sequence. That way the timing is exactly the same every night.
Safeties and backstage —
There are two safeties on the cabinet. Any time the show isn’t running, the corner of the cabinet sits on top of a stage jack, a wooden brace that sits between the counter top and the cabinet. It keeps the cabinet safely upright and steady. Storing it upright reduces stress on the cabinet joints (cabinets weren’t meant to hang at an angle).
As a second safety, there is a chain backstage which hangs from the lighting grid above the stage which clips onto the cabinet’s steel arm and holds it in place should the magnet be turned off unexpectedly.
When Stage Management sets up for the show, they have the Board Operator turn on the magnet with the light board, confirm that it is holding the cabinet securely, then remove the stage jack. The chain safety backstage remains on until about 3 minute before the actual drop. When we get close to the Boom cue sequence, the Production Assistant, who runs the deck backstage, removes the safety chain so it is only being held by the magnet until the moment of the drop.
Also, the Technical Director and Stage Management conduct daily checks of all the elements involved in the cabinet drop — making sure that nothing is bending, showing signs of stress, skewing out of 90-degree square, etc, and that it is hitting the same marks each night.
The boxes —
There are a total of 26 boxes stacked on top of that cabinet. Most of them are assembled into a “box sculpture.” They are attached to one another with several kinds of glue, tape, and thin strips of wood. The base of the box sculpture is lined with plywood, which is in turn bolted directly to the top of the cabinet. That way the cabinet can move and the boxes move with it but keep their orientation with regard to one another. There are seven boxes that aren’t built into the sculpture, and they are the ones that fall. They are stacked up there before each performance by the Production Assistant. Even the falling boxes aren’t random, though — our Scenic Designer and Props Artisan designed a look for the entire set of boxes, and each of the seven falling boxes is numbered and gets preset into the stack in a specific position and orientation according to a photo “map”. The idea is for the falling and fixed boxes to blend together visually so that when they fall, it’s a surprise.
Actor safety —
Though an empty cardboard box is not a terribly dangerous thing, probably no one wants to find themselves under a stack of falling boxes nightly. So we had to work with our performer, Blythe (who plays Jo), so that she was thrown back from the door by the blast into a position where she is clear of the falling boxes. Those physical actions are rehearsed on the set nightly before every performance, to help the actors make sure they hit the same mark each night, keeping them safe and in control.
Another trivia fact —
One of the sound sources that our Sound Designer used to design the rumble of the comet blast was an underwater recording of the Indian Ocean earthquake that caused the terrible tsunami in 2004.
what he wrote:
Stage sets aren’t built to withstand the impact of a massive comet hitting the planet. Few things are. That’s the problem designer Erik Flatmo and the Marin Theatre Company crew had to solve in “Boom,” Peter Sinn Nachtrieb’s apocalyptic sex farce in which just such an Earth-shattering event occurs. The actors, sound and lighting effects depict the moment of impact, but the set plays a big role as well – which means it had to be constructed from heavier materials than usual. The cabinet beneath that stack of boxes is a 400-pound steel-frame affair, attached to a solidly framed wall on pivot points that allow a degree of precise movement. An electromagnet (rated for 1,400 pounds), wired into the lighting system, holds it in place until its big moment. For added impact, one of the sound sources used when the comet hits comes from an underwater recording of the 2004 earthquake that generated the huge Indian Ocean tsunami.
(original article, with a set picture)
so there. now you all know. closes December 5, bay area peeps!