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With a special jig, a good bit of time and a LOT of cardboard you can make the very comfortable, very groovy ball chair. Since the bulk of the material is scrap cardboard this also makes a nice recycling project.
You can upholster the final chair like I did or just paint it and fill it with pillows. The plans for this instructable are for a 4' diameter chair that will (just barely) fit through a 30" doorway. You could scale it up or down easily depending on the size of person it's for and how much "surround" you want.
The chair stands on the base by gravity alone and the unattached design allows for easy readjustment of the ball. I like sitting in it more upright, and my daughter likes it kicked farther back.
I made this for my daughter's 13th birthday and it was a big hit. She's an avid reader and it makes a perfect cozy zone to open a book in. When she saw it she called me a "mad genius" which is high praise from a 13 year old. One of her first questions was "how will I get it to college?" I think she likes it and plans to have it around for a long time. It was a big project, but well worth the effort.
You can upholster the final chair like I did or just paint it and fill it with pillows. The plans for this instructable are for a 4' diameter chair that will (just barely) fit through a 30" doorway. You could scale it up or down easily depending on the size of person it's for and how much "surround" you want.
The chair stands on the base by gravity alone and the unattached design allows for easy readjustment of the ball. I like sitting in it more upright, and my daughter likes it kicked farther back.
I made this for my daughter's 13th birthday and it was a big hit. She's an avid reader and it makes a perfect cozy zone to open a book in. When she saw it she called me a "mad genius" which is high praise from a 13 year old. One of her first questions was "how will I get it to college?" I think she likes it and plans to have it around for a long time. It was a big project, but well worth the effort.
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Signing UpStep 1Sphere Cutting Jig
The most important part of this project is the jig. This large but relatively simple jig makes a perfectly shaped, hollow, half-sphere . The horizontal turntable and outer cutting arm cut the outside. The inner cutting arm cuts the inside surface, the hollow area of the sphere. Be aware that this jig needs to sit on a sturdy table or sawhorses. The pieces it makes are heavy so pick a place for it carefully.
The turntable doesn't need to be perfectly circular since it's the rotation, not the shape, that cuts the circle. In fact, an octagon shape would be preferable to a circle as the corners on the octagon would make for easier turning during a cut. An octagon shape would also be easier to layout and cut.
I used a few pieces of leftover 3/4 inch melamine for the turntable and base and standard 2 x 4 lumber for the swing arm and mounts. Some 3/4 inch plywood would work fine for the turntable and base. Don't use 1/2 inch or thinner material due to the weight it'll need to support. To make a round turntable use a router mounted on a long strip of material such as fiber board, screwed loosely to the radius point. Measure carefully for the center, mount the radius board and cut a perfect circle.
The swing arm arrangement is connected to its mounting points with 1/2 inch lag screws. These fasteners can be loosened to allow the arm to swing freely, or tightened to hold it in place.
Both cutters are simple utility knife blades. I used blades with holes so they could be mounted to their bases with small screws. These blades are inexpensive and easily replaced as they dull.
The inner cutter arm is made with a 2 inch by 3/4 inch piece of wood with a slot cut in one end for the swivel. Use an extra piece of stock on the other end, held in place with 2 screws. The inner cutter blade is trapped between the two pieces of wood and clamped in place by tightening the screws. The distance from the swivel mount hole to the blade clamp will determine the inner radius of the sphere. To get a 4 inch thick wall use a 24 inch outer radius and a 20 inch inner.
I am 6' tall and this inner diameter is comfortable enough when sitting in the chair with a papasan cushion. I would've preferred to make the ball slightly larger, but getting the finished chair through doorways was the limiting factor. A larger radius is more comfortable. It's less likely to feel like your head is being tipped forward.
A point I can't stress enough is take careful measurements. Measure your doorways very carefully or you will make a cool chair that will live forever in your shop.
See the instructions on step 8 for additional tips and considerations on how big the chair could/should be.
The swivel mount for the inner cutting arm is made with a 3/8 or 1/2 inch thumb screw with a 1/4 inch hole drilled in the center of the flat portion. The swivel mounts to the turntable using nylon-insert nuts and washers. These nuts allow for a precise adjustment without slipping. The swivel must spin freely, but not wobble. Use a thumb screw long enough to go through a pivot hole in the base. In this way the swivel mount also functions as the turntable axle.
The width of the base doesn't need to be exactly as noted in the plans (72") but beware that having too small a gap between the edge of the turntable and horizontal mounts will make for frustrating cutting before the layers of cardboard get higher than the mounts. Too close and your glued cardboard will keep bumping into the mounts and have to be cut away to spin the turntable.
The turntable doesn't need to be perfectly circular since it's the rotation, not the shape, that cuts the circle. In fact, an octagon shape would be preferable to a circle as the corners on the octagon would make for easier turning during a cut. An octagon shape would also be easier to layout and cut.
I used a few pieces of leftover 3/4 inch melamine for the turntable and base and standard 2 x 4 lumber for the swing arm and mounts. Some 3/4 inch plywood would work fine for the turntable and base. Don't use 1/2 inch or thinner material due to the weight it'll need to support. To make a round turntable use a router mounted on a long strip of material such as fiber board, screwed loosely to the radius point. Measure carefully for the center, mount the radius board and cut a perfect circle.
The swing arm arrangement is connected to its mounting points with 1/2 inch lag screws. These fasteners can be loosened to allow the arm to swing freely, or tightened to hold it in place.
Both cutters are simple utility knife blades. I used blades with holes so they could be mounted to their bases with small screws. These blades are inexpensive and easily replaced as they dull.
The inner cutter arm is made with a 2 inch by 3/4 inch piece of wood with a slot cut in one end for the swivel. Use an extra piece of stock on the other end, held in place with 2 screws. The inner cutter blade is trapped between the two pieces of wood and clamped in place by tightening the screws. The distance from the swivel mount hole to the blade clamp will determine the inner radius of the sphere. To get a 4 inch thick wall use a 24 inch outer radius and a 20 inch inner.
I am 6' tall and this inner diameter is comfortable enough when sitting in the chair with a papasan cushion. I would've preferred to make the ball slightly larger, but getting the finished chair through doorways was the limiting factor. A larger radius is more comfortable. It's less likely to feel like your head is being tipped forward.
A point I can't stress enough is take careful measurements. Measure your doorways very carefully or you will make a cool chair that will live forever in your shop.
See the instructions on step 8 for additional tips and considerations on how big the chair could/should be.
The swivel mount for the inner cutting arm is made with a 3/8 or 1/2 inch thumb screw with a 1/4 inch hole drilled in the center of the flat portion. The swivel mounts to the turntable using nylon-insert nuts and washers. These nuts allow for a precise adjustment without slipping. The swivel must spin freely, but not wobble. Use a thumb screw long enough to go through a pivot hole in the base. In this way the swivel mount also functions as the turntable axle.
The width of the base doesn't need to be exactly as noted in the plans (72") but beware that having too small a gap between the edge of the turntable and horizontal mounts will make for frustrating cutting before the layers of cardboard get higher than the mounts. Too close and your glued cardboard will keep bumping into the mounts and have to be cut away to spin the turntable.
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Thanks for the offer to buy, but to make a "living" building these I'd have to charge $5,000, you know? Definitely a labor of love. I joke with people I know that my favorite projects are big, novel, and more than a little impractical.
Thanks again!
It's wonderful all the consideration you put into the practicality of each element (like the design of your jigs, ergonomic considerations for the base height, and the ability to get it through doorways). I love that you continued to think about how to improve the project both during its construction and well after it was done.
I love the idea of making it with carpet pads. Do you think it would have to be thicker than 4" to reasonably keep its shape? You've inspired me and I would really like to try it when I am able (though it may be a few years until I get a suitable workspace - long term goal). I'll certainly let you know how it goes if I am able to do so.
You're a dedicated maker with serious brains, talent, and consideration for your daughter and your project.
If it would've been even 1/2" too big to get through a doorway, it would've been crushing. It's a weird shape and hard to simulate moving it. I literally had about 1/4" to 3/8" leeway getting into my daughter's room. That was a big "whew!" moment.
The carpet pad version would be interesting. It could be bigger, and the squishyness would help getting it into rooms. These chairs are heavy though, a squishy material would sag and/or deform. It could get all pancakey just sitting there.
I don't think it would need to be thicker at the current size, maybe not even if bigger. Carpet pad is pretty dense. The 4" (cardboard) wall is VERY solid. If I could turn these around quicker (and didn't have a regular job, wife, kids, etc.) it would be interesting to know how thin the wall could be.
Thanks for the compliments, they only make me want to keep going!
Also so good to get praise from a teenager, especially your own!
You're the man!
I'm also making another chair with the same jig. I bought a rotozip that I'm going to mount on the jig. The rotozip should be the right combo of power and weight. Not too much, not too little. Hopefully I'll get smoother cuts and the chair will look better unupholstered if I decide to leave it "natural".
Yeah, you could totally use wood planks. Shipping palette wood would work well, but I have a buddy that used palette wood for fence pickets and he said it was a lot of work pulling them apart, removing the nails and bits, all that prep stuff.
I thought it could be interesting to use this technique with carpet pad scraps. If you had the right glue it could work and be all squishy.
Great Project!
L
Here in Argentina this project is not possible: all the cardboard is recycled by the "cartoneros" (cardboarders?)
I'm sure this type of construction could be done with many different types of materials, really anything that is available as a sheet or wide plank.
A variation I've mulled over could use scrap carpet pad instead of cardboard. Find a carpet installer to get the pieces from and determine the best glue for the material and the sky's the limit.
Shoot, you could make a chair as big as you want and just squish it through any doorway.
If I could ever find enough cardboard I would so make one!
The jig and the use of cardboard is impressive.