Design of a CNC routed sheet good chair

Design of a

CNC

Routed Sheet Good Chair

by

Noel R. Davis

Submitted to the Department of Architecture in Partial Fulfillment of the Requirements of the Degree of Bachelor of Science in Art and Design - Architectural Design

at the

Massachusetts Institute of Technology

MASSACHUSETTS INSTITUTE OF TECHNWOLOGY

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@2006 Noel R. Davis. All rights reserved. The author hereby grants to MIT the permission

to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium

now known of hereafter created.

Signature of Author:

\o rDepartment of Architecture

May 19,2006

Certified by:

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Shun Kanda Senior Lecturer in Architecture Thesis Supervisor Accepted by:

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Professor of Architecture Director of the Undergraduate Architecture Program

Design of a CNC Routed Sheet Good Chair

Noel R. Davis

Submitted to the Department of Architecture on May 19, 2006 in Partial Fulfillment of the Requirements for the Degree of Bachelor of Science in Art and Design - Architectural Design

ABSTRACT

A chair of acceptable comfort, requiring minimum material and labor, was made by

de-veloping a system of parts and joinery, cut from sheet stock, using only one tool-a 3-axis computer numerically controlled router.

Comfort is achieved through ergonomic shaping of the chair components to embrace the geometry of the human body, and support several comfortable seating positions. All components were cut with a 3-axis CNC router using only one cutting bit. The joinery requires no additional hardware, glue or fasteners to hold the chair together.

The final chair design requires 12.5 square feet of 1/2" sheet stock. Cutting time on the router is 1.5 hours, and assembly, which requires only a mallet, takes 0.5 hours, giv-ing a total production time of 2 hours. Usgiv-ing Baltic Birch Plywood, the total material cost is $16.00. Using Oriented Strand Board, the total material cost is $2.88.

Thesis Supervisor: Shun Kanda Title: Senior Lecturer in Architecture

Thesis Committee

Shun Kanda, Senior Lecturer in Architecture, MIT Thesis Advisor John Ochsendorf, Assistant Professor of Building Technology, MIT Thesis Reader Christopher Dewart, Technical Instructor in Architecture, MIT Thesis Reader

Introduction:

The impetus for this thesis came from a desire to work with design and construction at full scale. While con-structing buildings at full-scale for an undergraduate thesis would be impractical, the design and construction of furniture incorporates many of the same principals as architectural design, and full-scale construction is not only possible, but gives the opportunity for users to experience the design as built rather than purely in models and drawings.

Many well known architects have designed furniture throughout the last two centuries, and in some cases their furniture pieces have become icons of design. Architects like Frank Lloyd Wright, Mies van der Rohe and Alvar Aalto designed chairs that not only enhanced and completed their architectural works, but remain as well recognized as many of the buildings they were designed for.

The design of chairs-defined in this study as a devices for sitting and resting the back, differentiating them from stools, which have no back rest-has been attempted by countless designers and craftsman over thou-sands of years. In order to give relevance to this particular investigation, it was necessary to first establish a set of goals and constraints to inform the design.

For this thesis the use of a single tool, a 3-axis CNC Router, with a single bit was permitted to produce the components of the chair. The chair was to be made from a minimum amount of material. A product of the previous limitations was the necessity to incorporate the joinery of the chair into its components so that con-nection hardware would not be necessary in the design. Critical to any successful chair is the comfort of the user, which could not be ignored in the development of this design. Finally, as a reaction to global economic

Process:

Following the criteria set forth in the thesis statement, an investigation encom-passing the design and development, to varying stages of completion, of eight chairs was carried out. The final iteration is presented as the completed product of the thesis, and the piece on which the success of the investigation should be judged.

Chair 1:

The first design iteration, called from here forth Chair 1, displays a timid use of the CNC router as the main tool. The router is used to cut foam formwork, around which, 1/8" plywood sheets are bent and laminated with glue to form the outer "shell" of the chair. The flat seat portion is cut from 1/2" plywood on the router and glued into place within the shell. This shell serves as the structure as well as the back support of the chair. The method of connection, or joinery, in Chair 1 is strictly glue-strength and the chair uses two sheets of 1/8" plywood for the shell and 1/4 sheet of 1/2" plywood for the seat. The form of Chair 1 is

inspired by Frank Lloyd Wright's Barrel Chair (Eaton 1997).

Chair 2:

Chair 2, the second design, uses a cantilevered structure to support the seat off the ground. Again, the router is used only for cutting foam formwork, and the method of connection is glue-lamination. The base of the chair, which supports

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the main bent-wood component, is not defined completely and has been modeled as a solid mass with a slot to hold the wood seat. Chair 2 requires 1 sheet of 1/8" plywood for the seat and an unknown amount of wood, metal or masonry to form the base. The structural form of Chair 2 comes from the precedent of Marcel Breuer's Cesca Chair [Wilk 1981].

Chair 3:

In Chair 3 the capabilities of the router to cut plywood and form integral joinery were investigated. A dado joint, common in traditional wood joinery, is made by cutting only part way into the plywood with the router, creating a slot. This slot was cut to receive, with glue for strength, the edge of another component of the chair. While Chair 3 uses the router more effectively than earlier designs, it also reveals a limitation of the router, its ability to cut dados only at 90 degrees to the material's surface. Without using an angled bit or a 4-axis router, this diver-gence from 90 degrees can not be created, and as a result the joinery in Chair

3 does not fit exactly and relies heavily on glue strength. Rather than introduce

new or more complicated tools it was decided, for future designs, to use the dado joint only in the applications where it could be cut accurately by the router. Chair 3 was built in model, but never at full scale, due to its joint inaccuracy. At full scale it would use 1 sheet of 1/4" plywood for the structural frame, seat and back. The form of Chair 3 is based on a number of designs of 3-legged chairs, including my own (Noel Davis') 3-legged Ash Chair.

Chair 4:

Chair 4 was designed in two steps, first the seat and then the leg and arm as-sembly. The seat is constructed using the dado joint within the router's 90 de-gree constraint, and a new joint, the half-lap. The half-lap joint, common in tra-ditional wood joinery, creates a recess in two pieces of wood, which overlap at these areas. The half-lap joint relies heavily on glue for its strength, but helps to

secure the accuracy of positioning between pieces. The back of Chair 4 has two laminated rails, each made of two 1/2" thick pieces glued together, which use dados to hold sheets of 1/4" plywood in a curved shaped. These 1/4" sheets form the seat and back of the chair. The laminated rails are joined to each other

by four slats, which are connected with half-lap joints. The seat of Chair 4 is

shaped ergonomically, following the contour of Charles Eames' Aluminum Group Office Chair (Drexler 1973).

The leg and arm system of Chair 4 demonstrates the first iteration of a mortice and tenon joint, adopted from traditional wood joinery. In this case the tenon, a

rectangular peg cut into the end of a member, fits into the mortice, a

rectangu-lar hole cut into the side of a member. The friction between the surfaces of the mortice and tenon provides a most of the joint's strength. Additionally, glue on these surfaces increases the strength of the joint. The structural system of the legs for Chair 4 builds on the design of Mies van der Rohe's Brno Chair [Glaeser 1977). Chair 4, requires 1 sheet of 1/2" plywood for the legs, arms and seat

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Chair 5:

In Chair 5, two significant changes came about, informing the final direction of the study. First, a time-tested four-legged design for the chair is adopted, shirking the notion that a useful and well-designed chair must stand on a unique struc-tural system. Second, the use of a series of small, repeated elements allows for contouring of the seat to fit the curves of the body, as well as provided a more ef-ficient use of wood. The connection method of Chair 5 requires the use of dowels to pin together all components. This introduces additional connection hardware into the design and detracts from the uniformity of the piece. For this reason, Chair 5 was never constructed, in model or full scale. At full scale, it would use 2/3 sheet of 3/4" plywood and four 20" dowels.

Chair 6:

Chair 6 pushes the use of small components further to contain integral tenon. Mortices are cut into the side frames of the chair and the slats plug directly into that frame. A slot is cut in each tenon to accept a wedge. This adaptation of a wedge-tenon gives the joint greater strength against separation. The wedges en-able the frames to stay securely in place without the use of glue in the joints. The slats are individually shaped to give a contour to the seat and back. Finally, the in-troduction of transverse frames connecting the two front legs together, and the two back legs together prevents racking, or lateral torsion distortion, of the chair. The resulting T-shaped section of the legs improves the chair's stability greatly.

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Chair 7:

Chair 7 further reduces material use to 1/2 sheet of 1/2" plywood by adopting a shorter frame, which supports the lower back rather than the shoulder blades. This design change was inspired by the chairs of Gio Ponti [Nelson 1994). The frame is also shaped to provide more material in areas of greater stress and tapers to smaller width in areas of low stress. The joinery is expanded to include a series of single and double width mortices and tenon, containing wedges only where necessary and remaining solid elsewhere. In this way a family of four joints, develops a language, or hierarchy, based on location and structural application. The last improvement is a bolder shaping of the seat to more closely follow the contours of the legs and hips. The deeper shaping also creates a sculptural feel to the seat of the chair.

Chair 8:

Chair 8, the final iteration, improves upon Chair 7 in the area of ergonomics. Greater attention has been paid to the shaping of the back and angle of the seat to provide three comfortable seating positions. The first position is a "perch" at the front of the seat in which the user ignores the back entirely. A second posi-tion provides for shoulder blade support when slouching in the chair to read or relax. Finally, a lumbar support provides upright posture for eating or working in the chair. Chair 8 uses 1/2 sheet of 60"x60"x1/2" plywood, so two can be made from a single sheet. In addition to the nude Baltic Birch plywood, which has

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produced in Oriented Strand Board, and red-stained birch to exhibit possible en-vironmentally conscious and aesthetic variations of the chair. The joinery uses no glue or external hardware, the wedges holding the mortice and tenon joints together being cut from the same sheet of wood. Chair 8 is the sturdiest, most comfortable and most aesthetically pleasing of all iterations.

One Tool:

For this investigation, all components of the piece of furniture are crafted on a single tool, the TechnoCNC 3-axis LC Series 4896 CNC Router. Further, while this tool has the ability to change between 8 bits, and is capable of contouring (two dimensional line cutting) as well as shaping (three dimensional surfacing), only the contouring ability and one bit are used. It is considered that the use of the shaping feature or other bits constitutes the use of an additional tool. The reason for the use of a single tool is to push the limits of that tool, and release its greatest potential, rather than relying on more or more sophisticated tools.

For Chairs 1 _{and 2, where the router is used to make foam formwork, a 1/2"}

diameter flat bottomed bit is used to cut the foam. In all other cases, Chairs 3-8, a 1/8" diameter flat bottomed bit is used for all operations.

While initially the joining of chair components was only glue, as mechanical joinery began to appear in the design, it became necessary to consider the capabilities and limitations of the router when designing joints [looked at more specifically in the Joinery section of this paper). Also, the router's strengths and weaknesses

needed to be considered when designing the shape of each component.

The router is accurate to 0.001" and can cut in any direction. In this way, the router has no preference for cutting straight lines or rectangles, like a

traditional saw. It can make holes of any shape, and cut partly through or com-pletely through the stock (material to be cut). These features of the router make it much more accurate than traditional saws and drills for making regular or ir-regular shapes.

The router, however, has two main limitations. Because it is a 3-axis router, it can only move along three axes, the X, Y and Z, and has no capability for rotation. This means the router can only plunge vertically into the wood, so the resulting angle between the surface of the stock and a cut edge will always be 90 degrees.

A router with more degrees of freedom (5-axis or 6-axis router) could make

angled plunges. Also an angled bit could be used to make angled plunges. How-ever neither of these tools is used in the design or construction, thus all joints and components were designed within the limitations. A limitation common to all routers is the inability to cut inside corners. Because the bit of the router is cylindrical, it is unable to make a clean, 90 degree, inside corner. Left behind is always a fillet with a radius equal to that of the bit's radius. This fact had to be overcome as well when creating joinery.

While in some instances, these limitations would serve to stand in the way of designing joinery, in this investigation they have been used to inform the design and improve the aesthetic of the piece, creating joinery with an identity that is inextricably linked to the machine that made it.

The bed of the router is 48" x 96", limiting the size of the stock used. In order to make the most efficient use of material, it was necessary to shape and lay out the components carefully on the cut sheet. The stock material, which must fit on the router bed, also affects the environmental impact of the chair as well as its perceived value as an object of design.

The concept of using a limited number of tools for furniture construction is evi-dent in many cultures, and was refined greatly by the Shakers of early America who held simplicity above all things in design (Andrews 1973). The idea of using plywood, or sheet goods is not unique to this study and has been considered in several ways. Charles and Ray Eames were on the forefront of using laminat-ed sheet goods to make three dimensional forms for furniture (Drexler 1973). More recently, with the growing availability of computer controlled fabrication machines, designs like David Kawecki's Puzzle Chair have taken advantage of laser cutting for fabrication (Byars 1997). This study seeks to further develop the use of CNC machines and Sheet goods for constructing three dimensional forms, in this case furniture.

Dovetail Jioning

Wedge Tenon Joint

Tusk Tenon Joint

Dado Joint Half-Lap Joint

Joinery:

Joinery has played a significant role in the development of design, and many pos-sible types were considered before finally adopting the final family of joints.

Initially the joining of components for the chair, in Chair 1 and 2, was purely glue. The thin sheets of plywood were to be laminated together using wood glue and a foam formwork. This type of joining relies entirely on the strength of the glue for

its structural integrity and requires considerable formwork and clamping to hold the piece in its correct shape until dry.

The first type of joinery produced on the router, for Chair 3, was a dado joint. This, like all the joints developed for this study, is an adaptation of a joint common to traditional wood joinery. Special considerations were made to produce these joints on the CNC router, as in a woodshop there are often several specialized tools used to make one specific joint. The dado joint is well suited to the router, because it consists of a groove in the stock with a flat bottom and perpendicular sides. The router makes this shape by plunging part way through a piece and making several passes to expand the dado to the proper width. The dado then accommodates the edge of another board, and is strengthened with glue. The strength of the joint depends on how tight the fit between pieces of wood is, and also relies on the glue strength.

The dado joint constructed on the router is not capable of joining pieces at angles other than 90 degrees. This means that the joinery for Chair 3, which includes dados at varying angles, is not capable of being cut precisely on the router, so Chair 4's design uses dados to join pieces only at 90 degree angles.

The next joint developed was the half-lap joint. In this joint, a portion of wood is removed from two pieces, so that when put together, their faces sit flush and the joint holds the members in position. The half-hap joint, used in the back-stiffening slats of Chair 4, serves to position the pieces accurately, but relies entirely on glue for strength.

In the legs of Chair 4, a mortice and tenon joint was used. This joint required adaptation from its original form to accommodate the limitations of the router. In traditional construction the shoulder of the tenon and the tenon meet at a precise 90 degree inside corner. However, the router leaves a radius in this corner, so a "return" is cut into the shoulder of the tenon removing the radius material and creating a clean inside corner. The same process is repeated on all four corners of the mortice, leaving a precise inside corner for the sharp edges of the tenon to pass through. The remaining half-circles left in the shoulders of the tenon and the corners of the mortices serve as a design element in the joint, revealing the process by which they were made. In this way, the limitations of the router add to the aesthetic, while the joint maintains a purely rational design.

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In Chair 6 the wedge tenon was developed by slotting the tenon and pounding a wedge, cut out on the router, into the slot. This wedge expands the tenon, in-creasing the frictional force between the tenon and the mortice and inin-creasing the strength of the joint as a whole.

In the last chairs, Chair 7 and 8, a series of variations on the mortice and tenon joint is created to suggest a hierarchy of function and placement. Larger, double tenon are used in the legs, where a larger portion of frame is held by a single joint.

Double wedge tenon are used at the tops and bottoms to hold the frame in place, and no wedge is used between. On the seat and back slats, single tenon are used because the joints repeat more frequently, and the wedges, again, are used only at the ends, to hold the frame in place. In between no wedges are used.

By creating an exact fitting, strong and aesthetically pleasing series of joints, the

joinery of the chair serves as its only decoration, and plays an essential structural role as well. The joinery is a unifying element, which holds the chair together physically and visually, and also reveals the nature of its construction, through small details like the returns, and wedges.

While often the use of new technology requires rethinking all aspects of design, including joinery, in this study time-tested methods of joinery were adapted to the advantages and limitations of the new technology. In this way a new system of

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Structure:

The structure, in the case of this investigation, dictates the form of the chair. The most obvious place where structural factors have informed the shape of the

members is in the side frames of Chairs 7 and 8.

In Chair 6 the side frames follow what could be considered the archetypal chair form. In elevation, there are essentially five points; one at the bottom of each leg, front and back, one at the seat front and seat back and the last at the top of the back. These five points are connected by members of constant width. No con-sideration is given to varying forces, moments or stresses within the members at any given position. The form is more or less arbitrary.

In Chairs 7 and 8, a conscious effort was made to shape the side frames based on the forces that would be experienced within them. Not by calculation, but rath-er by structural intuition, the legs are widened at the top to resist flexing, and nar-rowed at the bottom where there is less internal moment. The horizontal portion which supports all of the seat slats is deepened to provide greater resistance to bending under the weight of a person. The junction where the back leg, seat and back meet is thickened to resist the moment generated by an occupant's weight on the seat and the force of their back leaning on the back slats. By using structural principles to inform the shaping of the side frame, the frame begins to appear sturdier and more elegant, as well as behaving similarly. By shedding

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efficient, and by increasing material where it is needed, the chair becomes stiffer and more durable.

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Structural considerations were applied to other members of the chair as well. The seat slats, while shaped mainly to accept the contours of the body, also follow the general shape of the moment diagram for beam with fixed supports at both ends loaded at the quarter points, by two hipbones. They are deepest at their supports tapering to a constant depth inside the quarter points.

The joinery of the piece, as noted above, acts primarily as a structural compo-nent. Each mortice and tenon joint acts to resist three types of stresses within the joint: shear, moment and tension.

Shear is the force that would cause a tenon to break off of a slat or for a tenon to tear through the bottom of the mortice and side frame. This failure mode is counteracted by a deep tenon, 0.64", and by providing substantial material be-tween the mortice and the bottom of the seat portion of the side frame, 0.68".

Moment failure is represented by the slat bending and breaking or by the tenon twisting out of the mortice. This type of failure is prevented by a tight fit between the tenon and mortice, and by properly shaping the depth of the seat slat.

A tension failure, the most likely over the life of the chair, would result in the

tenon being pulled out of the mortice along the same path it was inserted. The standard joints, without wedges, prevent this through friction forces developed in a tight joint. The wedge tenon, however, creates a much stronger friction force which acts to prevent the tenon from pulling out of the mortice with use.

There are two members of the chair, which exist solely for their contribution to structural integrity. The front and back frames, which connect the legs of the two side frames, act to strengthen the legs against buckling, and more impor-tantly against lateral torsion. Lateral torsion is a structural weakness of many commonly used pieces of furniture. It occurs when the legs are not of sufficient section and do not connect rigidly enough to the frame of the chair. Many chairs overcome this problem by adding additional horizontal members between all four legs between the seat and the ground. Chairs 6-8 prevent lateral torsion by strengthening the moment connection between the tops of the legs and the rest of the chair. By connecting all of the legs to the seat with strong moment connec-tions, they become stiff enough to prevent lateral torsion. The "T" shaped section of the leg also increases its resistance to bending and buckling.

Maintaining a design identity, rather than an engineered assembly, the investiga-tion uses structural principles and intuiinvestiga-tions to inform the shaping and joints of the chair, but avoids being limited by strict structural calculations.

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Ergonomics:

It is impractical to design a chair without considering the comfort of its intended user. Yet, many chairs have been designed purely on aesthetic, structural or material guidelines with very little thought to their overall comfort.

Since at its core, this is an architectural study, it is impossible to design without considering the potential "client" who the chair is being created for. In this case, for simplicity of evaluation, it was necessary to design the chair for my

dimen-sions, my comfort.

The body dimensions, taken from myself, follow:

Overall Height: 67"

Ankle Joint to Knee Joint Distance: 15" Knee Joint to Hip Joint Distance: 16" Hip Joint to Shoulder Joint Distance: 19"

There are several aspects of a chair, which must be informed by ergonomics above all other considerations. First is the overall geometry of the chair, the height, depth and slope of the seat. Also included are the shaping of the seat, the shaping and position of the back.

All Chairs, 1-8, share common seat geometry. All have a seat height of 17 1/2"

In this investigation, ergonomics was not a serious concern until Chair 7. In that iteration, the seat is dished heavily to address the shape of the body it supports. The seat is dished in a horseshoe shape, to accommodate the legs, hips and buttocks, with a distinct rise between the thighs, to cradle the inside of the lower legs. The back of Chair 7 also includes a rudimentary lumbar support, rather than a shoulder rest. This serves to shorten the overall height of the chair as well as supporting a more upright posture.

In Galen Cranz's book, The Chair, the need for mulitiple sitting positions in a chair is made evident. Cranz emphasizes the necessity for people to move around in a chair to be comfortable, that any sitting position will become uncomfortable after a long period of time (Cranz 1998).

With this in mind Chair 8 was designed to facilitate three sitting positions. For this reason, the rise at the front of the seat, between the legs is flattened out to make more room for moving around.

First, the "perch" does not use the back of the seat at all. It involves sitting with upright posture on the front third of the seat, which is flattened like a plateau. The sitter uses only lower back and trunk muscles to support the upper body. This posture is quite comfortable, but cannot be held for long by most Western-ers who have weak lower back muscles, because they have always used chairs

The second seating position is an upright posture, with the hips all the way back in the chair, using the gently curved lumbar support for the lower back. This provides support for a similar position to the perch, but the added stability in the lower back allows longer sit times. The front of the seat is angled slightly down to relieve pressure under the knees, and behind the perch the rest of the seat is angled slightly up, from back to front. This helps slide the sitter back fully into the seat.

The third and final position, the "slouch," is achieved by sliding the hips forward, and allowing the shoulder blades to rest on the top of the back, which is angled back. This position puts the spine into an inward curve, which is not healthy for long periods, but is more relaxing than the other two positions and is good for activities like reading. The incline of the seat from back to front helps prevent the sitter from sliding forward, out of the seat.

Careful adjustment to each slat was made to create smooth contours in the seat and back of the chair, so as not to cut into the sitter. The seat slats are all aligned in the same direction, but the back slats are angled to create a gentler curve. The lower slats are angled slightly downward, the middle slats are horizontal, and the upper slats are angled slightly upwards.

While the seat does not incorporate padding of any kind, it is, in general, quite comfortable because of the careful placement, alignment and shaping of each rigid component. Clearly, with no adjustability, the chair accommodates a person of a specific size range, and larger or smaller people may require changes in the geometry of the chair to maximize comfort. With the simplicity of design, and automated fabrication, it would not be difficult to scale the chair up or down for larger or smaller people.

Material:

The final aspect considered in this study was material. At first, Baltic Birch ply-wood was chosen because of its availability and its high quality. Baltic Birch offers an appearance that is worthy of finish work, and requires no staining, painting or sealing before use. The finish is consistently clear, without knots or discoloration, and the wood is dimensionally consistent in thickness, which ensures precision in the joints.

Like all types of plywood, Baltic Birch has multidirectional strength, not suffer-ing from the grain-biased weaknesses of standard lumber, which means com-ponents can be laid out in any orientation to maximize efficient use of space on the cut sheet. Chairs 5-8 were made up of many small members in order to minimize material consumption. With two large side frames placed in the center of the cut sheet, the 23 small slats could be cut from various locations to use the maximum amount of available cut sheet. By decreasing the size of the cut sheet for each chair, more chairs could be cut from each piece of stock, decreasing the overall material use and cost of the chair.

Although Baltic Birch plywood was the default material for this investigation, sev-eral other options were considered, and one tested.

Plywood demonstrates a very efficient method for using the wood in a tree.

grain directions produces large, structurally multidirectional sheets of wood from fairly small trees, with very little waste. Construction grade plywood could be a more environmentally friendly option as it uses lower grades of wood, with more knots and flaws than Baltic Birch. This process means even less waste, as lower quality veneers are accepted for the plywood.

All types of plywood, however, use glues containing toxic ingredients to laminate

the veneers, increasing their harm to the environment.

Another type of wood composite is OSB, or Oriented Strand Board, which, like plywood, uses glue to bind wood into a sheet. OSB, however, uses waste chips of wood from sawmills and construction waste rather than veneers taken from newly cut trees, so it requires no virgin material. OSB is weaker, and less dimen-sionally stable than plywood, but when Chair 8 was constructed with OSB instead of plywood, the result was a geometrically identical chair that performed well and looked striking (For final material use and cost of each chair iteration, see Appendix A).

Also, for aesthetic reasons and increased longevity of material, an iteration of Chair 8 was made by staining red and sealing a sheet of Baltic Birch plywood be-fore cutting and assembling. The resulting chair also performed well, and looked vastly different than the original.

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Conclusion:

It is difficult to imagine a chair without a broader context. Chairs play a role in everyday life. They exude status and wealth, some are humble and functional, others are flashy and almost impossible to use (Bradford 1978). The role of the chair designed for this thesis is simple. It is meant to be a chair for a first apartment. It serves the role of dining chair, desk chair, reading chair and sitting chair. It is intended to convey both economy and quality of design. The chair is not intended to be revered as precious, but is intended to be durable and lasting in use.

Some chairs suggest luxury, especially those, which are designed for a specific task. The office chair is synonymous with power, the lounge chair is identified with wealth-the concept of lounging being unique to those with an excess of time [Bradford 1978). Chairs with specific tasks come with undertones of ex-travagance. But some chairs are merely utilitarian: the side chair, the desk chair. These chairs have often inspired the simplest and most elegant designs from some of history's best designers. Throughout the 1800s Michael Thonet de-signed simple chairs for the masses that today are icons of style and elegance. Charles Eames reinvented the way many people think about furniture and his simplest designs are timeless.

It is the intention of this thesis, this chair, to present itself in a humble manner, as a well thought out, finely detailed and carefully crafted masterpiece of everyday life that is not to be revered or coveted, but to be pulled out, dusted off and sat in for years to come.

Bibliography and References

Allen, Sam (1990). Wood Joiner's Handbook Sterling, New York.

Andrews, Edward D. and Faith Andrews (1973). Re/gion in Wood-A Book of Shaker Furniture. Indiana University Press, Bloomington.

Bradford, Peter and Barbara Prete (1978). Chair: The Current State ofthe Art,

with the who, the why and the what of it T homas Crowell, New York.

Byars, Mel (1997). 50 Chairs: Innovations in Design and Materials. Rotovision, New York.

Cranz, Galen (1998). The Chair W. W. Norton & Company, New York. Drexler, Arthur (1973). Charles Eames. Museum of Modern Art, New York. Eaton, T imothy (1997 ). Frank Lloyd Wright: The Seat of Genius. Eaton Fine Art,

West Palm Beach.

Glaeser, Ludwig (1977). Ludwig Mies van der Rohe. Mueseum of Modern Art, New York.

Nelson, George (1994). Chairs Acanthus Press, New York.

Vegesack, Alexander von (1986). L'industrie Thonet Ministere de la Culture et de la Communication, Paris.

Wilk, Christopher (1981). MarcelBreuer Furniture andInteriors. Architectural

Photo and Illustration Credits

All photos and images by the author unless otherwise specified.

P5. CNC Router Cutting Mortices

P6. (Top Left) "Cesca" Side Chair. Reprinted in MarcelBreuer: Furniture and

/nter/ors. Christopher Wilk, p74.

(Center Left) Chair 2, Bending Formwork

(Bottomm Left) Chair 2, Model

(Top Right) Chair 1, Sketches

(Center Right) Barrel Chair. Reprinted in Frank Lloyd Wright The Seat of Genius. Timothy Eaton, p57.

(Bottom Right) Chair 1, Model

P7. (Top Left) Noel Davis 3-Legged Ash Chair (Top Right) Chair 3, Sketches

(Bottom) Chair 3, Model P8. (Top Left) Chair 4

(Top Right) Chair 4, Precedent Sketch

(Bottom Left) Brno Chair. Reprinted in Ludwig Mies van der Rohe. Ludwig Glaeser, p64.

(Bottom Right) Chair 4, Side View

P9. (Top Left) Chair 5, Exploded Axonometric (Top Right) Chair 5, Sketch

(Bottom) Chair 6

P10. (Top Left) Chair 7, Sketches

(Top Right) Gio Ponti Chair. Reprinted in Chairs. George Nelson, p75.

(Bottom) Chair 7

P11. Chair 8, Cutsheet

P1 2. (Top) Chair 1, Bending Formwork

(Bottom) CNC Router Cutting Mortices

P1 3. CNC Router Cutting Frame Contour

P14. (Top) Shaker Chair. Reprinted in Religion i Wood- A Book of Shaker

Furniture. Edward D. and Faith Andrews, p43.

(Bottom) Puzzle Chair. Reprinted in 50 Chairs: Innovations /n Design and Mater/als. Mel Byars, p13.

P15. Traditional Wood Joinery. Reprinted in Wood Joiner's Handbook Sam Allen, p80 (Dado), p91 (Wedge Tenon), p99 (Tusk Tenon), p110

Photo and Illustration Credits (Continued)

P16. (Top) CNC Dado Model

(Center) CNC Half-Lap Model

(Bottom) CNC Dovetail, Axonometric

P17. (Top) CNC Wedge Mortice and Tenon, Sketches

(Center) CNC Mortice and Tenon Variations

(Bottom) CNC Wedge Mortice and Tenon, Axonometric

P18. Chair 6, Elevation P19. Chair 8, Elevation

P20. (Top) Chair 8, Wedge Tenon Detail (Center) Chair 8, Front Frame Detail (Bottom) Chair 7, Seat Dish Detail

P21. Ergonomic Positions, Sketch

P22. (Top) Chair 8, Position 1, Perch (Center) Chair 8, Position 2, Upright (Bottom) Chair 8, Position 3, Slouch P23. (Top) Chair 8, Position 1, Perch

(Center) Chair 8, Position 2, Upright (Bottom) Chair 8, Position 3, Slouch P24. Chair 7, Back Detail

P25. Chair 8, Seat and Mortice and Tenon Detail

P26. (Top) Chair 8 -OSB

(Bottom) Chair 8 - Red, Cutsheet

P27. (Top) Thonet No.14 Chair. Reprinted in L 'industrie Thonet Alexander von Vegesack, p25.

(Bottom) Plywood Dining Chair. Reprinted in Charles Eames. Arthur Drexler, p25.

P28. Chair 8 in Use

Appendix A

Chair Material Use and Cost

Chair Material Used

Baltic Birch Ply Chair 1 5'x 1O'x 1/8" 2.5' x 2.5' x 1/2" Chair 2 5' x 5' x 1/8" 5' x 5' x 1/2" Chair 3 4'x 8'x 1/4" Chair 4 1.5'x 5'x 1/4" 5' x 5' x 1/2" Chair 5 3.5' x 5' x 3/4" Chair 6 3.5 x 5' x 1/2" Chair 7 2.5' x 5' x 1/2" Chair 8 2.5' x 5' x 1/2" Chair 8 2.5' x 5' x 1/2" Oriented Strand Board (OSB) Material Cost per square foot

$0.56 $1.28 $0.56 $1.28 $0.92 $0.92 $1.28 $2.24 $1.28 $1.28 $1.28 $0.23 Total Chair Cost $36.00 $46.00 $40.96 $38.90 $39.20 $22.40 $16.00 $16.00 $2.88

Appendix B

Previous Furniture Design Experience

Appendix C

Essay on Modernist Furniture Design

Modernist Wood Furniture: Structure, Joinery and Materiality Replace Ornament The coming and going of aesthetic trends is a factor that defines design, and ensures the production of new ideas. Within this ever-changing aesthetic framework, a certain theme of functionality always remains constant. Interactive objects, regardless of their design must be able to perform the task for which they were created, or else they become merely for viewing. Louis Sullivan put forth the now famous idea that, "form follows function," referring to the ideal that an object must above all other things fulfill its functional role. This idea became a driving theme for the Modernist Movement in Architecture and Design in the early and middle parts of the 20th Century (Stimpson

60-61). Modernists favored design, which was, above all, functional. Yet the ideal did not

stop there. The goal of the modernist movement was to allow the functionality of an object to permeate the division between form and function, and become, itself, the aesthetic component of the design. Nowhere in the history of design is this theory better shown than in the design of furniture (96).

Modernist ideals in furniture design exist in furniture from all ages, each

encompassing a desire to forego outright ornamentation for a more clear form that relates to functionality. The structure, the joinery and the materiality of the piece are invited to do more than just hold the piece up, they are required to provide the aesthetic value of the piece as well. Through this process, the design of the construction, joinery and materials

become, simultaneously, the decisions about the final form of the piece. This idea forces every component of the piece to be considered on two levels, both how it will function as a part of the piece, and how it will be perceived by anyone who interacts with the piece (Cooke 12).

While the modernist ideals are very simple, the reasons that have brought designers to embrace them are as varied and complex as the designs that have been produced in this style. In order to understand the complexity of the driving force behind designers, the works that they have created within this mindset must be carefully examined. Because of the universal presence of wood construction throughout much modernist furniture design, regardless of geography or time frame, the selected pieces are

an examination of predominantly wood furniture, created between the early 1800s and

middle 1900s.

While certainly not the first examples of furniture to adhere to a truth of exposing construction and materiality, examples of Asian designs date back centuries, the

American Shakers are of notable importance for their contribution to furniture design ideals. A communal Christian sect, the Shakers were inspired by a widespread desire to praise and exalt god in all that they did. Their production of furniture was no exception (Andrews 5).

Shakers considered the furniture they designed and produced to be a carrying out of the will of God (17). They wrote that God considered it a "gift to be simple" and strove for perfection in all things they created, no matter how simple. Usefulness was of utmost importance, and anything made poorly or that contained frivolous decoration

communitarianism, wrote, "We have a right to improve the inventions of man, so far as is useful and necessary, but not to vain glory, or anything

superfluous" (7).

With respect to craftsmanship, labor and creativity, the founder of the Shaker Societies, Mother Ann Lee, said, "do your work as though you had a thousand years to live, and as if you were going to die tomorrow" (5). This statement reinforces a great respect for longevity in craftsmanship as well as a sense of urgency and excitement about labor and creativity.

Unlike many future modernist designers, whose goal was to advance high design and make it available to middle class people, Shaker's were not allowed identify themselves with the design of their pieces, meaning their individual contribution to design was not to be noticed or appreciated. (12)

The Shaker Side Chair, circa 1820s, is an excellent example of Shakers' clarity of design, quality of craftsmanship, and disdain for ornament. The simple turned

components are uniformly shaped, and sufficiently robust, without appearing too large. Small roundings on top act as handles and a cane seat provides a sturdy, comfortable sitting area. Finally, the back slats are curved gently to accommodate the human form, but not overly so as to suggest decoration. The Side Chair's construction is also logical,

and simple allowing the piece to be reproduced easily, making it more available to the common man (43).

With the common man in mind, Michael Thonet, championed an era of furniture designed for the masses. Thonet's chairs were merely the products of a desire and a process capable of making simple, high quality furniture, at affordable prices for millions of people. This goal was achieved through the invention of a process to bend wood to a desired shape that was inexpensive and infinitely repeatable. Thonet furniture is a modular assemblage of a finite number of parts, mass-produced in an assembly

line fashion at one of several of his factories. Thonet's process may be one of the first instances of the coming Industrial Revolution (Candilis 12).

Released in 1859, the N'14 chair is still in production today and in its lifetime at least 50,000,000 chairs have been sold (171). This chair, comprised of only six

components, is the epitome of reproducible design. Each component is manufactured by bending a cane of wood on an industrial machine. The six pieces are then sub-assembled and packed into crates to be shipped. The customer need only fasten a few screws, and the chair is ready for use (54-55). The chair's durability has been shone by the longevity of its production, and because of its clean, simple, rational design it has not fallen out of

trend in over 100 years. Surely this is not to say that the chairs popularity is independent of its form.

Clearly Thonet can be attributed with finding an elegant, curving form, which appealed to peoples' visual tastes, and from this idea he made many aesthetic variations to his designs. But ultimately, his initial formal decisions were based on an original necessity to produce a functional, affordable piece of furniture as simply and rationally as possible. The seemingly timeless quality of the chair can be attributed to its modernist lack of ornament and dependency, rather, on simple design and construction.

While modern ideals are well suited to mass

production, and serving the masses, the ideals can also apply to furniture designed more specifically for one instance. Some of the best examples of furniture designed for a specific place are the designs of Frank Lloyd Wright. Wright considered an architectural design incomplete without proper interior design, including furniture.

Furniture was to be a further expression of the architecture, while providing functions beyond human occupancy. Wright used his furniture designs to contrast or harmonize with other features in his designs, as well as to facilitate smaller areas of space within larger open volumes (Fowler 8).

the side of the table create a smaller, more intimate space, within the larger dining room for those eating at the table. The backs of the chairs provide a screen-like effect around the table area. The chair, though unadorned, begins to act as a formal addition to the room, a sort of functional ornament for the room (30-31).

Wright was always concerned with the materials used in his designs. He was vei specific about the quality of craftsmanship he demanded, and the durability of his desigr was very important. He was also concerned with the cost and availability of materials, especially in his affordable, Usonian houses. When it was practical, Wright used the finest, expensive, materials for his furniture, often choosing to work with white oak, quarter-sawn. The quality of material shows in the High Back Dining Chair, as the woo brings a warmth and tactile quality to the furniture. However, when budget was a question, Wright was willing to design in woods that were less expensive. Later in his career he designed many pieces for his less-expensive projects out of plywood, a fairly new product of technology, thought to be too crude for furniture by many (12-18).

The accepting of new technology to advance design is one often embraced by modernist designers. After the first World War, Europe set out improve their quality of life by incorporating high design into the lives of the masses. Along with this goal to mass-produce quality designs came a need to embrace new technology. With the assembly-line style of production introduced during the Industrial Revolution, the infrastructure was now in place to create large numbers of products with a consistency and speed never seen before. One designer who embraced, and pushed the bounds of technology at this time was the Finnish designer Alvar Aalto. During the 1930's Aalto

products of his experimentations and designs created an entirely new genre of furniture

(75-82).

The new material required a new language of design, new shapes, and new forms. And in modernist fashion, the decision was made to let these new forms, suggested by new materials become the defining nature of this furniture. Aalto's pieces, therefore, do not even closely resemble the archetypal wooden chairs the world had seen before, like Armchair 406, designed in 1938. The long swooping

curved forms of the chair and its cantilevered design, which allow for a dynamic reaction to the user (236).

Being such a new form, and so intriguing, visually, Aalto elected to make that the dominating characteristic of the chair, and merely used a woven web mesh to act as the seat and back. Thus the structure, which was entirely new, was allowed to become the dominating element of the chair (9).

Like the structure of Aalto's Armchair 406, Charles Eames' Dining Chair was also built around a new technological advance in wood. In Eames' case, this advance was the ability to bend a single sheet of plywood in a compound curve. When Eames finally achieved this breakthrough, the chair he designed to showcase it is very similar to Aalto's. Where Aalto's brand new structure prevailed visually over the subdued black

plywood, and suspended them, almost floating, by a thin, light metal structure, that nearly disappear behind the large, sculptural wood elements (Drexler 16-17).

While Eames embraced, and pushed the limits of technology, he often struggled with materiality. While compound-curved seat and back of the Dining Chair appear delicate, graceful and proportional in their placement, Eames had a desire to unify the elements of the chair. In this way, he wished to make the chair entirely of plywood, bringing the chair together as an assemblage of bent plywood forms. However, after many experiments with wood

supporting systems, Eames came to the conclusion that the metal frame, formally, was the best option.

At first, this conclusion may seem like a move away from modernist ideals, however, it is actually just the opposite. By admitting that forcing a unified materiality in the piece meant sacrificing the elegantly simple form, Eames was in fact making a decision that led the form of his piece to be more pleasing, because its simplicity harmonized with the other elements of the piece more fluently. The Dining Chair, with wooden legs, though quite beautiful, does possess a certain formal quality of being off-balance, or too heavy. Eames' decision to choose a new material, metal for the support of the chair, led the chair as a whole to become a more rational expression of forms,

While Eames created successful forms by using technology to minimize material, Hans Wegner has approached materiality in a different, more traditional way, through joining and shaping wood. Wegner's chairs utilize the intricacy and pattern of wood grain to enhance their aesthetic appearance. The organic shapes produced by bending, laminating and

shaping the wood are a form of ergonomic sculpture. No curve is placed merely for its look; rather each form is derived from its relationship with a particular part of the body.

A unique trademark of many of Wegner's chairs is his expression of both the backrest and

armrests as a single form. This curved piece, which becomes the dominant formal expression of the chair, is shaped based on its placement and its attitude towards the body parts it will support (Bernsen 98-99).

The support structure of Wegner's Round Chair, designed in 1950, is simply sturdy, similar in fact to Shaker designs, with unadorned, turned uprights supporting the seat, and back and arm rest. These vertical pieces can be made by machine, or turned by hand in large quantities to allow for larger production runs. The larger, more complex back and armrest piece must be glued-up as an assemblage of bent laminations, it can then be machine milled. It is in the arrangement of the back and armrest's constituent elements, and the revealing of their inner grain through shaping that this piece becomes a seemingly

patterning of the wood is a property of its inherent grain and the shaping is used to accommodate the human form, neither of these factors can be considered ornament without function, because it is in fact their function that brings about their visual splendor. It is in this way that Wegner, while maintaining a respect for clean, visible construction, is able to achieve such sculpturally appealing pieces, by allowing the form of the human body to reveal the character of the material (24-25).

With respect to the character of wood, few designers have come to a fuller expression of this innate quality than George Nakashima. Nakashima learned to craft wood from a fellow Japanese prisoner in a World War II internment camp who inspired in him the necessity to consider not only the look and feel of the wood, but a certain spirituality contained within it (Beyer 17, 23). This notion, similar to Frank Lloyd Wrights idea of architecture growing from the landscape, suggested that certain cues for the form of a piece are imbedded within the material itself. Rather than removing these flaws or inconsistencies within the wood, Nakashima embraced them as a driving force in his designs (30).

Where other designers draw up a piece and specify what type of lumber it is crafted from, Nakashima appears to start with the

lumber, and allows its characteristics to inform its embodiment. In this way the designer allows the material to not only enhance, but also dictate the form of the piece.

construction and forces, which enable the piece to function (34-35). The Conoid Bench with Back, designed in 1961, is a

fine example of a piece designed specifically around the flaws of material. The large "slab" of wood, which makes up the seat of the bench, is left, for the most part, how it was milled. The edges are left in place as a subtle cue about the nature of the tree before it became lumber. The large crack which begins at one end of the bench has not been filled, or sawn off, rather it has been held in its state by three butterfly

joints, and in this way exhibited as a flaw, but more importantly as a unique feature of this piece. The slab itself has inspired the design of the bench. The joinery of the piece

is clean and exposed. The spindles of the backrest clearly plunge directly into the slab

and reveal that the mass of the slab allows the back to function. The legs of the piece are small and sturdy, merely elevating the slab to a comfortable height for sitting. Like the spindles, they are connected, structurally to the slab, the unifying element of the piece. In this way, the slab, from which the piece was informed and created, connects and supports all other elements of the bench (34-35).

By considering a piece of furniture as the union of a specific piece of wood, a

method of joining that expresses and exhibits the inherent qualities and flaws of the material, and a simple structure which acts merely as a pedestal to showcase the "slab," a design is achieved which is at its base simple, yet upon further inspection reveals great complexity.

modernist design in wood, arrives at an interesting conclusion. The reasons that designers have shown for embracing modernist ideals are widespread, however they hint at socio-economic truths that have had widespread significance for ages, and they appear to come full circle in even this small sampling. The Shakers, an early example of modernist design took their inspiration from God, and a desire to fulfill their own spirituality through craftsmanship. Nakashima, at the other end of the spectrum, seems to find spirituality in the material itself, crafting his creations from a material spirituality, or divinity in nature. Others, like Thonet and Wright, used modem ideals to improve the quality furniture available to the common man, providing quality products of design at prices attainable by the masses. Aalto and Eames embraced technology as a way of bringing about new forms, which remain to this day, timeless, in their formal clarity and unadorned simplicity. Finally, Wegner used modernist design to embrace the human body, to meet and support its contours.

All of these examples show that modern design, as it has been considered so far, is not an idea brought about by architects and designers, but rather a mindset, or a way of life, embodied in design, set forth to improve the quality of life for people. The goals are not to create trends or styles, which can be priced and sold, but rather to create a new way of designing; a way in which forms are inspired by a clear expression of how they are made.

Works Cited

Andrews, Edward Deming, and Faith Andrews. Religion in Wood: A Book of Shaker Furniture. Bloomington: Indiana University Press, 1966.

Bernsen, Jens. Hans J. Wegner. Kobenhavn: Danish Design Centre, 1995.

Beyer, Steven, and Matilda McQuaid. George Nakashima and the Modernist Moment. Doyleston: James A. Michener Art Museum, 2001.

Candilis, G., A. Blomstedt, T. Frangoulis, and M.I. Amorin. Bugholzmobel: Bent Wood Furniture. Stuttgart: Karl Krammer, 1980.

Cooke Jr., Edward S., Gerald W. R. Ward, and Kelly H. L'Ecuyer. The Maker's Hand: American Studio Furniture, 1940-1990. Boston: MFA Publications, 2003. Drexler, Arthur. Charles Eames: Furniture from the Design Collection of the Museum of

Modern Art, New York. New York: The Museum of Modem Art, 1973.

Fowler, Penny, and Mary Anna Eaton. Frank Lloyd Wright: The Seat of Genius, Chairs:

1895-1955. West Palm Beach: Eaton Fine Art, 1997.

Pallasmaa, Juhani. Alvar Aalto Furniture. Cambridge: The MIT Press, 1985.

Stimpson, Miriam. Modern Furniture Classics. New York: Whitney Library of Design,