THE FIDGET CHAIR Wesley She
Jan Palach Memorial by John Hejduk Photos extracted from ArchDaily
Magis Spun Chair by Thomas Heatherwick Photos extracted from RIT Library
It was only after the completion of the design phase, that I realized the similarities between the form and texture of my chair and John Hejduk’s Jan Palach Memorial. Both composed of numerous sticks (or spikes in Hejduk’s work), one is to convey the idea of a sphere and it’s smooth transition in performing the sitting action of rocking and spinning, whereas the other one, also known as the House of the Suicide and The House of the Mother of the Suicide, is to celebrate the political and social solidarity of Czech’s democracy by honoring the Czech student Jan Palach, who self-immolated in the protest of the 1968 Soviet invasion. Coming back to present time, British architect Thomas Heatherwick also designed a chair for the motion of swinging and spinning. Despite an identical fidget action when sitting, the Magis Spun Chair took a completely different approach in form, texture and emotions. Of course, it is terribly arrogant comparing the freshman work of mine to the above two of the most successful architects and educators of our time. But I suppose such phenomenon of a frequently similar form, yet a completely different motive, or, a frequently identical motive, yet a completely different form, is what charms me the most in architecture. I guess that’s also why I am so addicted to the motion of rocking and spinning, always returning to the origin, always performing something different.
Contents
the extraction
the collection of body and motion data
the implementation the design of the chair
the jig
the design of the construction method
the pour
and the demolding of the chair
the completion
spinning and rocking in action
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08
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1
the extraction
the drawing out of body and motion data
The term fidget is defined as the making small movements, especially of the hands and feet, through nervousness or impatience. Putting that aside, my favorite form of sitting is actually when I carry out the two fidgets of swinging and spinning, the motion of swinging back and forth and the motion of a small rotation left or right. Whenever I read or think, the two motions not only releases stress mentally, physically speaking, it also stretches my body parts.
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the casting (1:1)
the drawing of the cast Since the motion of spinning is more like an add-on without the need of much referencing, more emphasis was put on the study of swinging. A 1:1 scale cast of my leg with a rotatable joint was first created to simulate the leg movement during the motion of swinging. Consecutively, a drawing of its contour in 1:1 scale was done to generalize the motion. However, several problems were conceived. Firstly, the motion of swinging is more of a function (swinging) follows form (the chair) than a form (the chair) follows function (swinging). The cast and the drawing created are all based on the sitting of an existing chair at my home so technically I was studying the relationship of my leg to that specific chair. Secondly, the muscle change of my leg during the motion was almost omitted since the cast was static and could not response to the rotation. A study on muscle was therefore carried out to determine a swinging angle and pattern my muscle desires.
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Myosin relaxes
Myosin contracts quadriceps femoris relaxes
Actin contracts
quadriceps femoris contracts
Actin relaxes
Eccentric contraction
Posterior hamstring contracts
Posterior hamstring relaxes
Gastronemius contracts
Gastronemius relaxes
Concentric contraction
Actin Myosin
Sliding Filament Model
Muscle changes when kicking
about muscles... Microscopically, there isn't such state as "relaxed" in muscle. There are only eccentric contraction and concentric contraction. Muscles are made up of millions of pairs of two filaments, actin and myosin, with an inverse relationship. When actin relaxes in eccentric contraction, myosin contracted. When actin is contracted in concentric contraction, myosin relaxes. Macroscopically, the inverse relationship continues macroscopically. For example, when kicking, the quadriceps femoris contracts, whereas the gastrocnemius, posterior hamstring etc. all relax. The take away from the two studies is that there isn't an ideal state for muscle, except when you frequently move so both kinds of contractions are addressed.
the sitting bones It is also pointless to simply implement the contours of my body to the chair. When sitting normally, our body weight is distributed mainly on the two sittingbones, the ischial tuberosity. The muscles and the flesh usually just act for shock proof or buffer purpose. Sitting on a mapped out contour might actually be more uncomfortable than a flat surface.
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STANDING
SITTING
TUCKING
Photogrammetry results
A total of 149 photos was taken to form the above meshes. Control points and lines are used to observe the muscular change of the posterior hamstring, the gastrocnemius versus the quadriceps femoris. leg photogrammetry To extract the data better and faster, a photogrammetry of three states of my leg was performed to study the extension of muscles of my leg. Since our skin is elastically attached to our muscles, a drawing of control points can clearly reflect both the eccentric contraction and concentric contraction of certain muscles on my leg. The three states are standing straight, sitting, and tucking. These data are then later converted into a drawing.
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110°
TUCKING 130°
From the right, the first, the third and the sixth were done according to the photogram For each leg, the top left block refers to quadriceps femoris, the bottom left refers
a drawing on the posterior hamstring, the gastrocnemius versus the quadriceps femoris
Rectangular blocks instead of the actual shape of the muscle were used to represent muscles for simplification purpose rocking angle of 108°- 90° = 18° was also found. Such definition of desirable was defined by the contraction of the mus
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STANDING 0°
45°
SITTING 90°
108°
mmetry results. The remaining ones were done taking the avergae of data collected. s to the posterior hamstring, and the one on the right refers to the gastrocnemius.
e. From this extraction, not only more body data was collected to determine things like chair height, etc., the desirable scle when they don't crumble and push into each other like starting from 110°.
the implementation the design of the chair
The very first attempt at translating the information was done using the normals of my buttocks to my thighs. The design was abandoned due to the massive amount of material required combined with the failure in addressing body movement.
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Unlike a static position where form follows the function (e.g. contour of a body), the motion of rocking of the user is lead by the form more. As a result, the idea is drastically reduced into a two-dimensional motion based on the mapped out normals of a circular curve.
The design is then expanded back into three dimensional, being the mapped out normals of a sphere. This allows the chair to swing in all directions. It also gave the chair the ability to spin naturally since the bottom of the chair is technically a “point� on a sphere.
20 mm
The idea of using a jig to accomplish such design was introduced by the tutors as an easy way to fix the angles and the positions of the wood sticks. The very first version of the jig treat the wood sticks in identical rows and columns, which raised some construction concerns.
Unlike lines, wood sticks have a certain thickness that cannot be omitted. The thickness of wood stick form a few problems. Firstly, extreme angles at the corners of two edges. It also suggested that a repeating element won't be suitable.
40 mm
20*20 mm wood sticks provide a higher resolution when compared with 40*40 mm wood sticks, thus a smoother spheric surface. The number of rows and sticks in the above design must also be even so that the chair can easily balance itself without falling.
? At this point, some other connecting elements were brought onto the table. One of them was to utilize the natural bending property of the wood to make the wood sticks "adaptable" to the jig. This method was abandoned due to its low accuracy and difficulty.
Epoxy resin was finally decided to hold all the wood sticks together. The property of liquid made it desirable in filling up the irregular space between the wood sticks. All it is left is how to hold the wood sticks together accurately.
A complex jig was eventually designed for the use of epoxy resin, which will be covered in later parts.
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Since the desired rocking degree is 18°, an array of rays coming out from an origin is created with each differed by 4° on the xz and yz planes (given 18°/4.5 = 4, 0.5 as the middle spacing is shared by two sticks).
The height from the bottom of my thigh to the ground level is 430 mm. Perpendicular frames of 20mm x 20 mm with a distance of 430 mm are created on each ray.
These frames are then used for lofting and capping to give the thickness of wood sticks. Minor rotations have also been made to the extreme angles at the end of the two edges.
Becuase wood sticks have a thickness, they cannot just converge to a point like lines, not to mention space must be reserved for sitting. As a result, the wood sticks are moved along the projected ray to leave space in between wood sticks.
Once the optimum spacing has been determined, the created surface is then examined to see if the rows and columns are enough or in excess to create a surface that can hold the 210 mm length of my sitting-bones.
The volume of the epoxy used is determined by the 85 N/mm² tensile strength of C15H16O2. After calculating the extreme moment with a weight of my body, the chair, the epoxy in vertical 2°, it is estimated that a thickness of 67 mm is required, which translates to about 1500 ml of epoxy resin.
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318 mm
430 mm
229 mm
construction drawings The entire chair consists of 100 20*20 mm wood sticks, each with a length of 430 mm. Mathematically, the sitting area at the top is a section of a 350 mm radius sphere, whereas the bottom of the chair can be interpreted as a section of a 780 mm radius sphere.
479 mm 677 mm
ISOMETRIC
TOP
NE 45°
BOTTOM
ALL SIDES
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the jig
the design of the construction method As mentioned previously, despite the fact that the central rays of the lofted wood sticks are composed by rotation of 4° on the XZ and YZ planes, the applied wood stick has another rotation along its axis (the ray). This combined with the extreme angles wood sticks made the construction of using a traditional two-dimensional jig less effective. While 3D printing might provide the best accuracy, it is way more expensive and harder to demold once the epoxy resin has been dried out. As a result, a jig using the section of the wood sticks is designed instead to provide accurate positioning and easy demolding process.
epoxy resin, 1500 ml of C15H16O2 C3H5ClO was not chosen despite a lower price. This is because of the fact that it is highly flammable and toxic. The C15H16O2 resin chosen has a 1:3 ratio and typically dries out after 3-4 hours.
hair dryer When mixing epoxy, it is inevitable to have air bubbles that would affect the uniformity and the strength of the epoxy. A hair dryer can drive away air bubbles by heating them up.
the reinforcements, 3 mm MDF To keep the entire setup straight and tight, so as to lower the systematic errors, some reinforcement components are made to tighten up the entire setup.
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the base and the quick release, 3 mm MDF The foundation is made by laser cutting tough 3mm MDF. A square was cut out for easy take off of the chair together with the sphere once the epoxy has dried out.
the sections and the tube, 1 mm cardboards and 8 mm PVC pipe The sections of the chair ensure the positioning and orientation of the wood sticks. A tolerance of 0.05 mm each edge is left for a smooth plugin. A hole was also reserved for a PVC tube to inject the epoxy resin.
the sphere, 2 mm and 1 mm cardboard, 4*4 mm wood sticks The sphere is the contour of the r = 350 mm sphere that the chair is based on. It provides a spherical platform for the wood sticks to lay on instead of intersecting. It was held together using wood sticks and wrapped with plastic tape. In addition to that, a layer of vaseline was applied to smoothen the demolding process.
the pillars, 4*4 mm wood sticks, 6 mm PVC pipe In addition to holding the entire setup together, the pillars also provide tube spacers for the sectioned cardboards. They are composed of 10 mm, 20 mm, 140 mm and 134 mm (if with reinforcement locks) spacers. The mix 10 mm, 20 mm set up is to lower the systematic errors on the imperfect plane of the wood.
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the pour
with the destruction of the jig
First test The chair was tested for the first time after demolding with a total dry period of 72 hours. It was proved to be comfortable and solid enough to hold my body for the action of rocking and spinning. At this point, all that was left are the removal of remaining cardboards and polishing.
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Cutting off of the excess epoxy resin The thin layer of excess epoxy resin on each side is peeled off using a chisel, whereas the thick ones are cut off using a saw carefully in big pieces. Despite the usage of a hair dryer, some air bubbles are found at the top of the chair. This is because of the air being trapped inside the wrapping tape for the sphere component. Fortunately, the small area only affects the outlook at the top but not the structure of the chair.
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Sanding, polishing and the white paint Once all the excess epoxy are dealt with, a thin layer of white acrylic paint was applied to hide all the air bubbles and inconsistency in colours. To make the entire chair more aesthetically coherent, sanding paper covered with epoxy powder were used to sand off all the wood sticks. Toothpaste, in replacement of polishing cream, was also applied to give the epoxy a matte finish.
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the completion and the action
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I hereby affirm that all the materials attached herewith are my own work produced independently. Special thanks to (in alphabetical order) Mr. Christian Lange, Mr. Donn Holohan, Mr. Harvey Chung and Mr. Ulrich Kirchhoff for their continous supports and guidence. Thank you for your time in reviewing through this portfolio.