Vortex Tunnel
How to build a spinning Vortex Tunnel
Part 1 - The Rings
Like I said somewhere else, I am not saying you should build the tunnel this way. I'm just documenting how I built MY tunnel.
The Vortex Tunnel is basically 3 rings cut from sheets of plywood spinning on bicycle wheels. Metal pipes connect the rings, the inside is covered with fabric to make a tube and the whole thing is spun by a motor. A painters scaffold makes the 22 foot long bridge that you walk on to go through. When you are inside a 20 foot long spinning tunnel that's spinning at 4 rpm (and you're not) it IS nauseating.
Each ring is 10 feet in diameter. That means the radius (distance from the center point to the outside of the ring) is 5 feet. I took a 6 foot piece of angle iron and attached it to a 1 foot square of plywood. Then I attached a router with a straight bit to the plywood, bit extending through a hole. At the other end of the angle iron I made a hole (5 feet away from the bit). This hole is the pivot point that the router assembly swings on. It is attached to the top center of a rack I made to hold sheets of 1/2 inch plywood square and in place. When the router assembly is swung across, it cuts a perfect arc in the plywood. See picture below.
Do it again, and again, and again.
The next jig cuts the proper angle on the end of each of the arcs so they fit together in a circle properly. A base is made from the leftover bottom piece of one of the 4x8 sheets (with the corners still on it). A line is drawn up the exact vertical center. One of the arc pieces is screwed to the piece lining up the edges exactly. The line extends onto this piece. That's it. That's your jig. If you sit an arc piece against the piece you screwed down you can extend the line onto the piece. It makes more sense in these pictures.
Now the lines are cut with a chop saw and the pieces fit together in a perfect circle. I had to make the last piece smaller than the others to complete the ring. This jig cuts the proper angle on any length piece.
My Vortex Tunnel rings are 2 ply. Since the tunnel has three rings I needed 6 rings worth of arcs. Here they are laid out ready to be assembled.
First I used Gorilla glue to hold the pieces together, Then I used 1/4 inch bolts with framing straps across each of the seams. I offset the seams on the top and bottom layer on each ring. These things are never going to come apart. Since I knew I would have to transport the rings, I divided them into 3 sections and left off the Gorilla glue on the seams at 3 points. I used extra bolts at those spots.
The rings are held in place with 10 foot metal pipes. That's threaded pipe, not conduit. Threaded flanges are bolted to the rings. The pipes and flanges are from the plumbing section of Home Depot (next to the iron pipe). There are four sets on each ring. The flanges have bolts going through them, through the wood and AND through a metal framing strap on the other side. I didn't want the bolts to be able to pull through the wood. Obviously, I couldn't screw the pipe into the flanges at both ends at the same time. The whole lefty-loosey righty-tighty concept is backward on one end. I had to screw the flange onto one end. After screwing the pipe-flange assembly into the flange that's bolted to the next ring I went back and bolted the first flange to the first ring.
Building the Vortex Tunnel base.
The Vortex Tunnel base is 3 pieces. It is made mostly of 2x4 sandwiching a 20" bicycle rim on each end. Two 10 foot 2x4s are laid side by side about 6 inches apart. A couple 2x4 uprights are attached with screws reinforced with metal angles as in the picture. There are holes drilled in the upright that the axle of the bike wheel is inserted into. I cut a piece of steel tube with an interior hole big enough for the axle and inserted it into the hole in the 2x4. This was to keep the threaded axle from digging into the wood. Over the years I learned that these should have been glued in place to keep them from vibrating out.
I also added the extra wooden triangle braces seen in the above picture. Originally, I had 2x4 attached to the ends for stability. Since we had to set up outside for a couple of years, the slightly uneven ground made those braces impractical (they didn't sit completely flat). Besides, to make these new braces I had to use the chop saw, table saw, router AND nail gun, so it was a good day.
After the tunnel is assembled, the aluminum bridge is passed through the rings. The bridge is actually a very long painters scaffold. A platform is made at each end (a quick, but solid staircase) and the bridge sits on that. The wooden railing is made from 2x4 lumber attached to the bridge with long bolts. Also, 6 black light fixtures are attached to the bottom of the bridge.
Large sheets of very light weight black material are stapled to the inside edges of the rings. It is then lightly splattered with fluorescent paint.
The walk through is VERY dizzying. Even in the daylight, although nobody gets to walk through in the daylight.
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