Paper Stream

   Occasionally we are asked to create a continuous stream of paper or money or something like that.

   The classic approach is to lower a motorized rubber wheel (or the drive axle of a cheap radio control car) onto a stack of paper (or money, or whatever).

   This creates the desired effect and is best used to make a sort of snowstorm of paper.

   So, when I was asked recently to rig an office copier to spew out copies at an accelerated rate, that's the first thing I tried. However, it wasn't really the right way to do what they asked for.

   The client wanted the paper to come out of the machine like it was a printer working at a faster speed, that is one copy after another, but with a regular space between copies. I realized that the traditional paper spewing rig was not controllable enough.

    I realized that I needed to feed the copies one at a time into the spinning wheels. This posed a couple of problems.

   First, without a stack of paper under the wheels there was too much friction to overcome so the wheels would not spin. I solved this problem by mounting the front axle of the car (the non drive axle) under the spinning wheels. I now had a pair of wheels spinning above a pair of wheels being spun, sort of like a pitching machine. If I fed a piece of paper into the wheels it was ejected nicely, and changing the speed of the wheels of course changed the trajectory of the paper.

Drive wheels could be either above or below, in this case they are on top. As you can see, copier was trashed to make this all work. Upper wheels are hinged on a long arm so they are resting on idler wheels by their own weight.

   The second problem was how to feed the copies in one at a time in a regular fashion. I had actually encountered this problem before, but was able to feed the paper manually from behind a wall or something. 

   That wasn't an option in this case, so I made a simple conveyor belt using gator board and diffusion, operated by pulling a piece of trick line. I positioned the copies on the belt, each on on top of the next and about an inch ahead, so as I advanced the belt the papers were fed into the wheels one after another. By varying the speed of the belt I was able to vary the space between the copies being ejected from the machine.

Here is the outfeed  of the copier. You can see the feed mechanism. We added the ramp to give the copies more lift as they left the machine. The bracket on the left was a mount for a piece of trim that hid the mechanism.

These aluminum rails were installed to make it easier to position the conveyor belt. I made two identical belts to reduce reset time.

Here is a screen grab of the copier doing its thing. The conveyor is sticking out on the left side. It was hidden by the actor.

   If I get the opportunity to tackle this kind of project again I would like to motorize the conveyor belt so that the speed (and therefore the spacing of the copies could be more consistent. But overall I was pleased with the results, as were the clients. Best of all, I got some nice comments from the guys on the crew.

Slow news day at Fast Company

The folks at Fast Company magazine put together a nice little piece about some of the rigs that we use in the business, with some cool action pictures.
http://www.fastcompany.com/magazine/163/ed-fountain-catapult 

BLAST FREEZER

Baby it's cold inside

I was on a job and the director asked me to find a blast freezer to super chill some drinks in a hurry.

I had never heard of this device so I did some research and found that:

a. Blast freezers are incredibly expensive to buy

b. The company that rents all of the kitchen equipment to tv commercial productions doesn't own one, probably because of a.

So I decided to make one.

I went to the home center and bought a cheap awning window (like in a basement) and a couple of sheets of 2" foam insulation, as well as some foam panel adhesive in caulking gun tubes.

I cut a piece of plywood the size of the window plus 4", then cut a hole in the plywood to fit the window opening, like this:

I screwed the plywood to the window, then constructed a box out of the foam, as you can see, consisting of a top,bottom, two sides and a back. I made my box 10" deep. I cut the foam with a handsaw and glued it all together with the foamboard adhesive, using 3" drywall screws to hold everything together while the adhesive set up.

Using a 4" hole saw, I made a hole in the center of the top and bottom, and then placed a foam baffle over each hole, supporting it on little foam blocks, like this:

You can see the 3" screws I put in two corners to keep this together while the adhesive set up

I had a 4" blower lying around, so I used it to circulate the air in the freezer. I ran an elbow out of the hole in the bottom and used a small length of flexible duct to connect it to the intake of the blower .

bottom view

Then I used another piece of the duct to connect the output of the blower to the "ice tunnel" which I glued on top of the freezer box.    This  is simply a foam box

 with a removable lid which connects the output of the blower to the 4" hole in the top of the freezer.

The ice tunnel, lid removed. Dry ice arranged in tunnel fashion also

lid taped on

I also put a cookie cooling rack shelf in, supported by foam blocks glued to the side walls, and some battery powered LED lights:

In operation, I simply filled the ice tunnel with dry ice and turned on the blower. The blower sucks the air from the bottom of the box and sends it through the ice tunnel and back into the box through the top hole. So the air should get colder and colder as it is recirculated. And it does. The temperature dropped amazingly quickly and bottomed out at about minus 44 degrees Fahrenheit:

Check out the minus sign on the left. The flexible aluminum ducting behind the thermometer is covered with frost.

Whatever I put in the freezer got cold pretty quickly, so it seems to work. Of course we never used it for the job, but now I know how to make one, and so do you.

SLIMED

Recently I was asked to provide a slime explosion for a television ad.

 In the spot, I was told, a kid jumps up and punches an object,
causing it to explode and soak the kid (and the room)
 with gooey slime. 

This was a last minute job and they asked me to prep the
 job the day before the shoot.
This is not enough time to figure out and troubleshoot a rig like this.

 Since I was working, I called on friend and

 fellow rigger Ashley Hollister to do a preliminary day of prep.

We talked it over and came up with this idea: 

  A bowl full of liquid with a larger flat plate suspended just above it.
 Through a hole in the flat plate an air mortar would blast

 a shot of air, forcing the water/air frothy mix  out through the space between the bowl and the plate. (An air mortar is simply a pressure tank with a large diameter, quick acting valve which empties the tank instantly, creating a powerful blast of air). Here is a picture of an air mortar: 

The valve is an air operated butterfly valve, it opens quickly and offers little resistance to the airflow.

 Here are pictures of the rig being tested at Ashley's shop in Brooklyn:

 

We thought it looked promising.

However, the following day at the tech scout (a walk through at the filming location with the creative team and the heads of each department), it became clear that it wasn't.

The director's wish was for something more like an explosion in all directions, a "hand grenade" is how he put it.

So we tried modifying what we had, and came up with this:

 

 

While this created a satisfying bit of mayhem, it was clearly time to take a different approach.

The idea of the liquid hitting a plate still seemed right, but we needed a way to have it hit a 

vertical plate from behind, causing the liquid to spread in all directions.

Here is what we came up  with:

The blast from the air mortar travels through the blue hose and enters the cylinder on the left.

A measured amount of slime has been poured into the apparatus from the top, through this valve:

The valve was opened only to fill the rig with slime. The ball on the right was to deflect the slime out of the back of the rig, the plumbing cap on the left deflected the slime on the camera side.

When the air enters the rig it pushes the slime up and out both sides of the tee.

Here is a test of the rig:

  

As you can see, it worked quite well and everyone was happy with what we came up with.

We also made a smaller version of this for some tighter shots of slime hitting people and things:

 

This slime gun works on the same principle but has a self contained "air mortar".

Here is a test we did with this gun:

This gun worked ok, but saw limited use. As is often the case on this kind of job, it's hard to beat the flexibility and speed of a prop man with a bucket when it comes to heaving slime.

Speaking of slime, it was concocted from a secret recipe by Propmaster Pete Wright and his crew.

We made a hell of a mess.