Hi there, My name is Lex Ortiz. I'm a Junior Technical Director at the University of Cincinnati and today, we're going to build a Pneumatic Sci Fi door.
Things you need:
28" stroke Pneumatic Cylinder
Pneumatic hoses and flow control
Pneumatic 5:3 Valve
2 sticks 2x4
3/8" bolts and washers
3/8" Lag bolts
4x8 reinforced sheet of luaun
1/8" aircraft cable
3 sheaves for 1/8" AC
Flat stock steel
small child for sound effects.
Step 1: Building the Frame
I've included a drafting detailing the main frame of what were going to be building, I built it myself using only 2x4 and wood screws. The most important thing is to limit your axis' of movement on EVERYTHING. This includes bracing the door (seen above) from moving on the x-axis only, as the effect has the door moving along the Z and Y axis'.
Step 2: Mounting the Door.
As seen in the picture above, i used a 3/8" bolt through 3/4" ply to attach the door to the frame. It is important to not tighten the bolt completely, so as to allow the door to pivot on the bolt. The plywood must also be sturdily attached, as this point will have a lot of weight on it during the effect.
Step 3: Crafting and Mounting the Head Block
Because this is a 3:1 lifting ratio, we're going to need a robust head block for our aircraft cable to go through. I punched some holes in flat stock and offset the 8" sheaves by about the width of the wire. One side has to have 3 holes in it, and that's where we'll mount it to the frame from.
I myself mounted it to the top of the frame by drilling a hole through the width of the 2x4 and bolted it together.
NOTE: you may want to reinforce this by having more than one point of contact. You can easily do this by welding an extra flat stock piece to the piece bolted to the frame, and connect that to the hypotenuse of the frame (see above)
Step 4: Prepping and Mounting the Cylinder
We're going to have to create a custom rod end to allow the cylinder pull the wire rope in the system. to do this, I welded some scrap steel into a "U" and punched holes in the sides to mount the sheave, and in the bottom to allow me to mount it to the end of the cylinder.
We also probably need to create a 90 deg. mount as we're mounting this to the side of the frame. I created two identical pieces of flat stock and welded them together. i then welded them to a plate as seen abode and sanded the tab until the pin fit perfectly through all holes. We also want to put as many washer as we can on that pin, we want to eliminate wiggling on the pin.
The bottom of the cylinder and the foot we just made get lag bolted onto 2 blocks of 2x4, which are through bolted to the frame (see picture above)
Step 5: Weaving the Aircraft Cable
OK, so were ready to weave the AC cable through the system. this is a bit tricky as it must be woven exactly as shown in the picture above. The cable begins by being mounted to the door and ends mounted to the frame.
Step 6: Prepping the Pneumatics
Now we're going to route our air supply through our valve and into the cylinder.
Only run the system at 50 psi. even then I would reccomend flow control.
Step 7: Final Step
This one can be the most daunting part of the build. We're going to turn it on. Be sure to pressurize both ends of the cylinder before you start, or the door will take off at max speed.