Introduction: Air-Powered Star Trek Style Door
I always wanted a piece of Star Trek and the Disney Monorail in my house, and one thing they have in common is that they both have automatic sliding doors. It would be the perfect, most geek-ified entryway for my bedroom.
Edit: Not every detail is included in this Instructable. I did the best I could using pictures I had taken 4 years ago. There are some more details on my blog if you would like to read more: http://uiproductions.blogspot.com
To be acceptable as a permanent renovation to our house, I knew the door had to have a normal appearance, as well as be practical and maintenance free. To reduce the number of moving parts (and maybe for a little coolness factor) I decided to make the door air-powered. The air would be supplied by a small compressor and storage tank located in the attic. In order to open and close from the inside and out, the door needed a little bit of brainpower. I decided to use a small PIC microcontroller, my platform of choice still to this day. Arduino didn't exist back then.
With a rough plan in my head, I drew a quick CAD model of the door and the brackets that would connect the pistons to the door halves. I was ready to start purchasing parts.
Step 1: Buy Parts / Tear Out Wall
Here are some of the parts I used:
- Craftsman 1 Gallon Air Compressor / Tank
- 32" wide, solid wood door from Home Depot (to be cut in half)
- Pocket Door Track from McMaster.com
- Two 16" stroke, 3/4" bore pneumatic pistons from McMaster.com
- A 5-way, 12V solenoid-operated valve from McMaster.com
- Various pneumatic hose, fittings, a regulator, push-on hose connectors, two valves for air supply and purge
Your parts will vary depending on your door size, your wall configuration, etc.
Start tearing out your wall with a hammer, crowbar, or any other destructive tools you can find laying around. This is the fun part of the project!
Step 2: Install the Track, Hang the Doors, and Patch Up One Wall.
I proceeded to cut the solid wood door in half with a circular saw, sanding the edges when done. I considered using bi-fold doors which are already the right size, but they didn't give the appearance of a normal door when joined together.
With all of the interfering studs removed from the wall, I held the rear drywall in place with 3/4" thick wood boards, which would still leave room for the door to travel through the wall. I added a new 2x4 stud on one side to support the pocket door track, and installed the track and a door half using the included hardware. You can see below how the one half will slide into the wall cavity.
Some strips of drywall, mud, and trim take care of the hallway with no problem.
Step 3: Fabricate Door Bracket / Install Pistons
Next I had to fabricate a bracket to connect the pistons above the door to the actual door. I welded up a bracket out of some steel flat bar from Home Depot and attached it to the back of the door with a spacer block. I could have really used some more advanced tools at this point, but I had to work with what I had at the time. You can fabricate this bracket from sheet metal, steel bar, wood, or whatever you can find.
With the two brackets fabricated and installed, I mounted the two 16" pistons above the door, side by side. Air supplied to the back of the pistons would open the doors, and air supplied to the front of the pistons would close the doors, as seen below. I rigged up the valve temporarily to test everything out.
Step 4: Electronics
For the electronics, a simple on/off switch would have worked. But I wanted to get a little fancier and control the timing of the doors opening and closing. I made the circuitry from components that are readily available at Radio Shack and Sparkfun.com. The circuitry just waits for the button to be pushed then switches the air valve on so the door will open. After a few seconds, the valve switches back off and the door closes.
I mounted a DIP socket, a relay, and a few other components on a Radio Shack perf board, and placed the whole thing inside a plastic junction box. I also wired in two AC power switches, one supplying AC power to the wall adapter for the circuitry, and the other supplying power to the compressor in the attic. I wanted the whole system to be enabled and disabled from this "control panel", including the air supply.
Step 5: Test It Out / Patch Up the Wall
After countless cycles of testing and tweaking the door operation with the wall open for a month or two, I finally felt comfortable closing up the wall. Here you can see some of the new drywall starting to go back up.
From there it was just a matter of painting the wall, and it was back to looking stock. I purchased a blank white wall plate from Home Depot. I drilled it out for an illuminated pushbutton and a 3-position keyswitch, both of which I bought from McMaster. I also purchased a plastic hatch door from McMaster for the control box. Lastly, I added an air conditioning vent above the door. This lets the air venting noises be heard, and it also provides me access to the valve and pistons should anything go wrong.
After you've tested the door and patched up the wall, that's about it! Good luck with your project and feel free to post comments and ask questions if I skipped over anything you might need help with. Thanks for reading!