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In late 2008, the first Cardboard Cantilever Chair came into the world, wrapped in paper-mache and held together with five threaded rods: www.instructables.com/id/Cardboard_Cantilever_Chair/
However, this chair has a number of notable failures. First, the paper-mache surface, while nice-looking, smooth to the touch, and durable, was a huge amount of work. In the same vein, an attempt was made to save labor by constructing the chair out of strips cut on a table saw; however, those time savings were negated by the need to miter every strip to fit into the cantilever profile. To tie the layers together in the absence of big clamps, threaded rods shoot through the whole chair in five places, which in many ways defeats the purpose of making a cardboard chair in the first place -- what's the point if you're just going to throw a couple of big pieces of steel in the middle of the thing? Last, the form is clumsy, with five-inch wide strips for strength making a big, bulky, and extremely heavy chair.
The goals for Cardboard Cantilever 2.0 were to address all of these weaknesses: made only from glue and cardboard, no paper mache or steel fasteners; cutting the strips without miters to save time; cutting the strips to length after lamination, also to save time; and attenuating the cardboard strips' width so as to make the chair visually lighter and more delicate.
In addition, I wanted to explore the idea of making multiple copies of the same chair as precisely as practically possible. To make multiple copies, the cost had to be kept to a minimum. To that end, the steel was eliminated, but also using commercial glue was out due to the volume needed. Instead, this chair was made with wheat paste, keeping the glue cost to an estimated two to three dollars per chair. The other issue with multiple copies was finding a way to make the lamination process more refined so the layers lined up better and were clamped under even pressure while the glue dried for maximum strength.
The finished photos below give a good idea of how this one stacks up next to Cardboard Cantilever 1.0, as well as scans of drawings I made to develop the form and the clamping jig. For an explanation of the ergonomics and physics of the cantilever form, refer to the link to the first Instructable.
However, this chair has a number of notable failures. First, the paper-mache surface, while nice-looking, smooth to the touch, and durable, was a huge amount of work. In the same vein, an attempt was made to save labor by constructing the chair out of strips cut on a table saw; however, those time savings were negated by the need to miter every strip to fit into the cantilever profile. To tie the layers together in the absence of big clamps, threaded rods shoot through the whole chair in five places, which in many ways defeats the purpose of making a cardboard chair in the first place -- what's the point if you're just going to throw a couple of big pieces of steel in the middle of the thing? Last, the form is clumsy, with five-inch wide strips for strength making a big, bulky, and extremely heavy chair.
The goals for Cardboard Cantilever 2.0 were to address all of these weaknesses: made only from glue and cardboard, no paper mache or steel fasteners; cutting the strips without miters to save time; cutting the strips to length after lamination, also to save time; and attenuating the cardboard strips' width so as to make the chair visually lighter and more delicate.
In addition, I wanted to explore the idea of making multiple copies of the same chair as precisely as practically possible. To make multiple copies, the cost had to be kept to a minimum. To that end, the steel was eliminated, but also using commercial glue was out due to the volume needed. Instead, this chair was made with wheat paste, keeping the glue cost to an estimated two to three dollars per chair. The other issue with multiple copies was finding a way to make the lamination process more refined so the layers lined up better and were clamped under even pressure while the glue dried for maximum strength.
The finished photos below give a good idea of how this one stacks up next to Cardboard Cantilever 1.0, as well as scans of drawings I made to develop the form and the clamping jig. For an explanation of the ergonomics and physics of the cantilever form, refer to the link to the first Instructable.
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Signing UpStep 1The Jig
To make the layers as consistent as possible throughout the lamination process, I built a clamping jig to align and hold the cardboard under compression as the glue dried. If I were to do it over, I would use thicker plywood (at least 3/4"), as this plywood warped under the considerable pressure exerted by the threaded rods and wing nuts. However, keeping tot he spirit of the project, all this wood was salvaged -- the plywood from a job site, and the dimensional pieces from pallets and other scraps.
To start, draw out the profile of the chair on a piece of plywood. The pieces I used were a little under three feet square. You can print the drawings from the first step to replicate this exactly, but you could also design your own. If designing your own, keep in mind a few things: the length of the piece that rests on the ground needs to be as long or longer than the total chair to keep it from tipping back excessively; the leg, or vertical piece, should be as short as possible for comfort; and the seat needs to also be short to keep it from acting as too much of a lever.
Once the chair is plotted out, screw 2 x 4s to the back of each piece of plywood as shown as bracing. Add this bracing even if you use thicker plywood, to keep the jig from wracking.
Next, draw a circle for a peg at each intersection of the chair. Tape over the wood with packing tape to seal it from spilled glue; you could also varnish it, but the tape is quicker and cheaper. Drill out the marks you made for the pegs, which will register the cardboard into alignment. I made mine from hickory pegs donated by my landlady; you could use dowels, bolts, pipe, whatever. Since my plywood was so thin, I had to add little scraps to the backside of the bottom piece of the jig as shown so the pegs sat down into something. If you use thicker plywood, these pieces could be eliminated. It is important that the pegs be secure, because they will take some abuse and you want them to be accurate for layer after layer. I glued and screwed them in their sockets.
In each corner, put an 18" x 1/2" diameter threaded rod to work as the clamping element. Lay the top plate onto the bottom plate so that it is held up by the pegs and rods; reach in and scribe each peg's placement onto the top plate. Drill out those holes at least an 1/8" too big so you have some play in aligning the plates later. Test that it all fits together.
To start, draw out the profile of the chair on a piece of plywood. The pieces I used were a little under three feet square. You can print the drawings from the first step to replicate this exactly, but you could also design your own. If designing your own, keep in mind a few things: the length of the piece that rests on the ground needs to be as long or longer than the total chair to keep it from tipping back excessively; the leg, or vertical piece, should be as short as possible for comfort; and the seat needs to also be short to keep it from acting as too much of a lever.
Once the chair is plotted out, screw 2 x 4s to the back of each piece of plywood as shown as bracing. Add this bracing even if you use thicker plywood, to keep the jig from wracking.
Next, draw a circle for a peg at each intersection of the chair. Tape over the wood with packing tape to seal it from spilled glue; you could also varnish it, but the tape is quicker and cheaper. Drill out the marks you made for the pegs, which will register the cardboard into alignment. I made mine from hickory pegs donated by my landlady; you could use dowels, bolts, pipe, whatever. Since my plywood was so thin, I had to add little scraps to the backside of the bottom piece of the jig as shown so the pegs sat down into something. If you use thicker plywood, these pieces could be eliminated. It is important that the pegs be secure, because they will take some abuse and you want them to be accurate for layer after layer. I glued and screwed them in their sockets.
In each corner, put an 18" x 1/2" diameter threaded rod to work as the clamping element. Lay the top plate onto the bottom plate so that it is held up by the pegs and rods; reach in and scribe each peg's placement onto the top plate. Drill out those holes at least an 1/8" too big so you have some play in aligning the plates later. Test that it all fits together.
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I was just as shocked.
Also, check out my notes on working with 1/2 inch cardboard. It's much harder to get, but well worth the effort.