How Green Was My Machine

At Loki’s suggestion I did some designs for a potential green machine last week. The major parameter for this work was that the machine should be able to eject or “throw” the boxes that were painted last week. Also, if possible, it should be machine-ish in appearance and have a part which appears to break off in a jagged crack at the end of the scene.

Multiple views (click picture for detailed view)

Hopefully the following diagrams, along with accompanying text, will assist in achieving those meager goals.

First of all the green machine as I’ve designed it is about 2/3 of a plywood box (roof, three sides). Originally I was designing an entire plywood box that you’d have to get inside, but figured it would be difficult to fit many green boxes inside it. Also an entire plywood box would make it difficult for the person inside to maneuver properly to eject the boxes. So this green machine is meant to be built around a doorway (without a door). In addition there’s a wooden cross-piece/brace screwed into place to keep it from accidently tipping forward. This brace effectively clamps the green machine onto the doorframe.

Detailed front view. (click picture for detailed view)

Gray stuff in the diagrams or dotted lines just indicate something’s hidden from view. Generally this is because the thing in question is hidden behind a wall (either the wall of the building or one of the walls of the machine it’s self). The notable exception is the break-away piece of face sheet that’s merely been painted over.

Detailed and exploded side views. (click picture for detailed view)

As for hatch for the boxes to shoot or be thrown out of. Let me tell you, I thought up a couple semi-mechanical ways to do this. But ultimately I think the most reliable way to get it done is a simple hatch mechanism and with direct human muscle-power. With that being the case there’s a simple hatch that gets pulled open using fishing line drawn through a hole in the top of the machine.

Just make sure you cut the hatch hole large enough for the boxes to go through it with a couple inches to spare on each side. Then make the hatch cover at least half an inch larger on each side than the hatch hole.

You’ll probably want to hide the hinges to the hatch cover so they aren’t obvious. If you decide you want to hide them make sure to taper the upper edge of the hatch (as shown in the diagram) so the hatch can open further. You’ll need it to open past 90 degrees in order for the boxes to really shoot out without hitting the hatch and being knocked back down.

Which brings us to the ramp. As you can see there’s a little shelf-like ramp built into the back of the machine. This ramp serves three purposes:

  1. Both the sides and bed of the ramp help aim boxes going out of the hatch. Without such a staging area I can forsee a situation like a 2 year old trying to put a square peg in a square hole: He’ll eventually get it in there, but not very quickly or elegantly. The staging area also allows you to get boxes ready to go and exactly in the right spot even before the hatch is opened.
  2. The bed of the ramp is angled so boxes get pushed slightly upward as they head toward the hatch. Hopefully this will allow folks to push the boxes so they really SHOOT out instead of just falling out to the base of the machine.
  3. Unrelated to the actual boxes: since the ramp sticks out past the back edge of the doorway the crossbrace can be attached to the bottom of the ramp to help hold the machine against the doorway.

You’ll see a curtain in the diagram as well. This is my poor solution to avoid having the camera see the stage hands operating the machine from behind when the hatch is open. I know I warned Loki against just putting black sheets around everywhere, but in this case I think it’ll be ok. The sheet will actually be “inside” (ie. behind) the machine and hopefully just look like some sort of dark interior, difficult to see.

Keep the room behind the machine relatively dark and make the curtain black. Once a person has a box staged on the ramp they’ll actually push the box through the curtain, keeping the curtain between them and the box so their body and or hands don’t accidently show through the hatch. At worst it’ll look like the box is being pushed by dark fabric (cause it is, duh), but at least it won’t look like it’s being pushed by a human.

Now, there’s also the issue of the dramatic “crack” that’s supposed to appear in the machine when it breaks. This one stumped me a bit at fist. If you think about it you don’t REALLY want to be able to see what’s inside the machine when it cracks open. It’ll either look like a person in there or just the inside of a plywood box.

The solution I came up with (and I really don’t know how well this will work) is to make the front in two layers:

Backing sheet – This is a little sheet of plywood will mostly not be seen. The forward side of the backing sheet (the one that faces toward the camera) will be painted either black, or with some pattern suggesting electronics or mechanic stuff. You might want to drill a couple small holes in the backing sheet so smoke can pour through it.

Face sheet – This is the layer that will mostly be seen. Cut a jagged chunk out of the face sheet (as shown). You might need a jig saw or saber saw for this. Then assemble the top, face, and sides as shown. You’ll still have the backing sheet and the cut out chunk of the face sheet when this is done. Attach the backing sheet behind the face sheet as if you’re patching the hole you’d cut in the face sheet. Then put the piece of the face sheet that you cut out back in place but DO NOT attach the cut out chunk of the face sheet using screws or nails. Just paint the face sheet as many times as necessary until the seem disappears. You may need to let the paint dry and then sand it to make the seem not stand out. The only thing holding the chunk of face sheet in place should be paint.

When the time comes you can pull this jagged chunk of face sheet off to reveal the backing sheet underneath. You may want to do this using fishing line tied to an inconspicuously placed nail.

… or so it should work in theory.

As a random decoration for the front of the machine I had this image of blinking lights in my head (like you see for complicated machines on all kinds of old Star Trek and sci-fi movies) and the only thing I could think of that would be similar and easy for us to do are Christmas lights. I figured maybe you could drill some holes through the front and backing sheets and poke some Christmas lights through. But to keep it from looking like Christmas lights put some sort of translucent plastic over each one, like halves of pingpong balls or those plastic caps you get from soda bottles, or something.

A couple notes on materials:

Plywood – You’ll be using plywood for this alot I assume, from my memory plywood grades are things like A-A, A-B, A-D, B-C, etc. These indicate how smooth and knot-free the wood is on each side. For instance A-A plywood should be perfect on both sides, however A-B will be a little worse on one side and A-C will be alot worse on one side. Anything that isn’t at least partly “A” (ie. B-C) can’t be guarnteed smooth on either side. I think you’ll need something with at least one side saying “A”. Make sure the smooth side is facing out (ie. the rough sides are facing toward the inside of the machine.

Screws and nails – It might just be old theater training but I suggest you use screws instead of nails for most of the construction. For one thing screws will tend to snug up alot of joints if used properly and they should be relatively easy to get out when you are done. Make sure the screws are in a couple sizes as needed so you don’t end up screwing all the way through things and have sharp screw points poking out the other side. Make sure to use screws with countersunk heads so you can paint over them and they’ll hopefully disappear.

Pilot holes – Also, for the love of all that is stagecraft: pre-drill pilot holes for your screws. Drilling a hole before you screw a screw into it should help prevent splintering which just looks shoddy. The drill bit used to drill the pilot hole should be relatively wide but always a little smaller than the width of the screw you’re putting into it.

How to attach sheets of plywood edge to edge. (click picture for detailed view)

Attaching plywood to plywood – One thing I didn’t point out in the other green machine diagrams but occurs to me now is that putting screws into the edge (rather than the face) of plywood is really not a great idea (see new plywood attachment diagram). It tends to seperate the grain of the wood and make it splinter. Also screwing into the edge of plywood just isn’t a very strong connection. It’s best to take little chunks of some non-plywood (like 2×4) and screw both sheets of plywood you want to attach into that (again see plywood attachment diagram).

Attaching the front to the sides. (click picture for detailed view)

Cracks and seams – One other construction detail comes to mind, and you should be able to see this in the diagrams, but just to emphasize: You really should make sure the seams where the sides and top attach to the front are along the sides (see picture) rather than pointing toward the front. I’m not sure if this is just a standard stagecraft practice in case the “flat” (term for a frame with a sheet of wood across it) is later used to support weight, but it has the advantage of keeping any cracks produced by the seams slightly out of view of the audience if the flat is used as a backdrop. Along these lines you’ll probably want to make the sides and top of the thing as a frame and then attach the front, rather than building the sides and top onto the front sheet first.

That’s about all I think I’ve got on this one. Hope this is of some use to you guys, and that the project goes well whether it is or not.

Note to Bear and/or Loki: I couldn’t get the pictures to space nicely with the text on the page and sadly don’t have time to play with it at the moment. If you guys could spruce up my shoddy workmanship (and erase this paragraph when you’re done) I’d be much obliged.

About Peter

This guy lives in Boston MA with his beloved wife and two kids. You can get some idea of his likes and dislikes from posts on this website or elsewhere.

2 thoughts on “How Green Was My Machine

  1. Pete, as I’ve already written you personally, I think that your design is exceptional.

    What is so wonderful about it is that not only does it met the specifications I asked for, but you’ve designed something that I could potentially build relatively inexpensively (this is if I can figure out how to nail the nails into the boards with my limited carpenter talents).

    I mean let’s face it, my Green Machine was more of just a place holder.

    You’ve come up with something that has passion and vision. I can’t wait to build it.

  2. Thanks again.

    Seriously though: Use countersunk woodscrews, pre-drilled pilot holes and an rechargable electric drill/screwdriver if you can afford to. I think you’ll find these things alot less problematic than nails for the work at hand.

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