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Step 4Hosin'
Pin the hose at one end with a screw and a washer. Then "sew" up the sides.
At each hole, brace your feet against the frame and pull the hose through with both arms as hard as you can, to stretch the hose tight. Being rubber, it will inevitably sag over time, so it's best to get it as tight as possible now.
These hoses can handle a tremendous amount of force. Not shown here is my first attempt at this chair, using reclaimed pallet wood. I stretched the hose so tight it snapped part of the frame off, which flew up and almost busted me in the jaw. The plywood in this version is a much stronger material.
That said, you can see in the first photographs in the introduction that sides of the frame curve inward and the legs belly out from the tension of the hose. The threaded rods are also bent into slight "smiles" from the same force; this isn't such a bad thing, as it bends away from the surface of the seat, accommodating the sag of the hose when someone is sitting there.
Sit down and enjoy!
At each hole, brace your feet against the frame and pull the hose through with both arms as hard as you can, to stretch the hose tight. Being rubber, it will inevitably sag over time, so it's best to get it as tight as possible now.
These hoses can handle a tremendous amount of force. Not shown here is my first attempt at this chair, using reclaimed pallet wood. I stretched the hose so tight it snapped part of the frame off, which flew up and almost busted me in the jaw. The plywood in this version is a much stronger material.
That said, you can see in the first photographs in the introduction that sides of the frame curve inward and the legs belly out from the tension of the hose. The threaded rods are also bent into slight "smiles" from the same force; this isn't such a bad thing, as it bends away from the surface of the seat, accommodating the sag of the hose when someone is sitting there.
Sit down and enjoy!
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Thanks,
DJ
please see two pictures i added at the end of the first step.
these are of the first attempt at making this chair. i used the engineer's approach: i built a very rigid frame out of dimensional lumber braced with plywood. and you're absolutely right; it didn't flex an inch while i was stretching the hose through it. instead of flexing, it failed suddenly and catastrophically. the failure was caused by, amongst other things, splitting along the grain of the dimensional lumber.
the first solution that comes to mind is to make a more rigid, more massive frame to contain alll the stored energy in that stretched hose. however, i quickly realized that to do that, i would have use massive pieces of wood or weld the frame from steel or alumnium.
the other solution is to work with rather than against the tension. i made the frame out of plywood, which is very strong yet flexible. it also has no grain, so holes made for the hose or by fasteners couldn't be a starting point for a split along the grain.
now, essentially the whole chair is in tension: the rubber is stretched; the plywood is bowed; and, as the legs splay out, they actaully attempt to stretch the rod between the back feet, as well as lever on the rods above, evening out some of the compression. as the rubber slackens over time, i can just pop one of the two screws that pin the hose in place, re-tension, and screw back in.
this solution responds to all the tensile forces actively, instead of passively. it also allows the whole chair to act as one "web of tension" instead of pitting rigidity against flexibility -- because, sooner or later, one of those forces has to win.