Here's how to build and setup a coffin that opens and closes using pneumatics! This project is great for Halloween but can be used for other occasions like birthdays, parties, etc. This setup is about the simplest way you can make it and still retain quality. This setup is very easy to do (can be done in one day with the necessary parts) and cheep I believe it cost me about $50-60 to go from start to finish. The other nice feature is that it doesn't require a lot of CFM's so even small compressors are able to run it.

Materials:

1. 2X Pine boards measuring 1"x12"x8'
2. 2X Sheets of Plywood measuring 1/4"x4'x8'
3. 4X Small L brackets
4. 1X pneumatic 6" stroke cylinder. Grainger-Air Cylinder
5. 1X wing bolt (mine was a 1/4"-28 threads per inch)

You will also need some screws or nails I used a box of 1 3/4" screws.

Tools:

1. Circular saw or Jig saw
2. Screw-Gun (drill with screwdriver bit)
3. Tape measure
4. Sharpie

Cut List:

1. 2 Pine boards 22" long with a 15 degree angle on one side and a 45 degree angle on the other.
2. 2 pine boards 52" long with a 15 degree angle on one side and a 45 degree angle on the other.
3. 1 pine board 17" long with two 45 degree angles.
4. 1 pine board 14" long with two 45 degree angles.

Assembly:

Now you can begin assembling the coffin by using those 1 3/4" screws or whatever you bought to put it all together. The way I did this was by screwing the screw into the pine just a little and then turning it almost parallel to the wood so that it goes through the angle you cut and into the other piece of wood. I also added some supports to the place where the 15 degree angles meet.

For the base and top I just traced my frame using a sharpie onto the plywood and cut it out with a jig saw. This assured a perfect fit (if I was perfect at cutting).

Now it's time to screw the base to the frame using that box of screws again. Then using the 3" hinges you bought you can put the top on. Make sure you only put hinges on the part below the 15°joint or it will not open.

Now it is time time to add the pneumatic cylinder to make it open. First you need to widen the holes on the L bracket if they don't fit over the pivot mounts already. Then you need to flatten the "wings" on the wing bolt so they will stick out straight. To do this is used a vice. Then you need to get in the coffin and mark where the brackets need to be so the coffin will open all the way. Then you can screw in the L brackets so that the bottom of the cylinder in mounted. Then do the same for the top using the wing bolt like the pivot mount on the bottom. Mark it with the coffin closed and open it all the way keeping the holes over their marks and see if it is open enough for what you want, then screw it in.

Now you can paint it and hook up the air to it. I also added a strobe light and fog machine for effect. To activate it I made a pressure activated switch and buried it under the dirt path past the coffin so when people unsuspectingly walked by they would trip it and get a little Halloween surprise.

2 Comments to “Pneumatic Coffin”

1. Justin — September 28, 2008 @ 8:15 am
   

   How did you make the pressure trigger? can you give instructions on how to do that by any chance? I have been trying to figure this out for a prop I am building..

   thanks and happy haunting this year is going to rock cause halloween falls on a friday so that means more people to scare will be out and about

   [Reply]

   miles reply on October 4th, 2008:

   What I did was cut two pieces of 1/2″ plywood and sandwiched blow gun between the two pieces. When the top piece of plywood is depressed it depresses the handle of the blow gun and lets air run through. I attached the line to the coffin directly to the output of the blow gun and straight to the cylinder using copper tubing. Here is a link to the type of blow gun I used. http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100086568&N=10000003+90401+524401

   [Reply]

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