Digital Fabrication Midterm Report

Fabricated Light

Abstract: 

Experimenting with computer design and CNC manufacture, I plan to create a light fixture at a larger scale that plays with light and shadow.  The design will comprise of machine-cut wood components that will later be assembled utilizing the advantages of friction.  Through this project, I plan to explore the potential of Rhino software in collaboration with the process of using the CNC.  Fabricating individual components that fit together as a three-dimensional sphere is an intriguing design challenge to investigate.  How can fabricated modular planes be applied to benefit three-dimensional design?

Introduction:

The background of the CNC machine begins in 1775 when John Wilkinson invented the first manual laid cylinder boring machine, which was one of the first practical machine devices.  In 1800, Henry Maudslay developed the metalworking lathe, a machine tool that held the piece of material being worked in a clamp, or spindle, and rotated it so a cutting tool could cut the surface to the desired contour.  In 1818, Eli Whitney developed the first milling machine, which operated in much the same manner, except the cutting tool was placed in the rotating spindle.  The material was mounted to the machine bed or worktable and was moved about under the cutting tool through the use of hand wheels.  Besides being monotonous and physically exhausting work, the ability of the operator to make identical parts was limited. Slight differences in operation resulted in variation of the axis dimensions, which, in turn, created poorly fitting or unusable parts.  A means to operate the motions of the machine automatically was needed.  Early attempts used a series of cams that moved the tool or worktable through linkages.  As the cam rotated, a link followed the surface of the cam face, moving the cutting tool through a series of motions.  The cam face was shaped to control the amount of linkage movement, and the rate at which the cam turned controlled the feedrate of the tool. These early machines were difficult to set correctly, but once set, they offered excellent repeatability for their day.  

The modern CNC machine grew out of the work of John T. Parons during the late 1940s and early 1950s.  After WWII, Parsons was involved in the manufacture of helicopter rotor blades, which gained him knowledge of precise machining of complex shapes.  Parsons soon found that by using an early IBM computer, he was able to make much more accurate contour guides than were possible using manual calculations and layouts.  Based on this experience, he won an Air Force contract to develop an automatic contour cutting machine to produce large wing section pieces for aircraft.  Utilizing a computer card reader and precise servomotor controls, the resulting machine was massive, complicated, and expensive.  However, it worked automatically and produced pieces with the high degree of accuracy required by the aircraft industry.  

By the 1960s, the price and complexity of automated machines had been reduced to the point where they were applied to other industries.  These machines used direct current electric drive motors to manipulate the hand wheels and operate the tools.  The motors took electrical instructions from a tape reader, which read a paper tape approximately 1 in (2.5 cm) in width that was punched with a select series of holes.  The position and sequence of the holes allowed the reader to produce the necessary electrical impulses to turn the motors at just the precise time and rate, which in effect operated the machine just like the human operator.  Simple computers managed the impulses and were often called Numerical Controlled machines.  A programmer produced the tape on a typewriter-like machine and the size of the program was determined by the feet of tape needed to be read to produce a specific part.

Today, the modern CNC uses digital codes instead of manual punched tape and is being used to produce a broad range of products.  For instance, Liam Hopkins and Richard Sweeney created the Borealis lampshade, a part of a series of lights, which are the results of experiments with computer design and CNC manufacture.  Each lampshade comprises of machine cut components, which are assembled and finished by hand in the studio.  They also created the light modulator, a computer-generated form that was converted into modular sections cut from birch plywood using a CNC machine.  Emphasis was placed on limiting the number of unique module shapes in order to simplify construction.  Twenty six unique units are used in total, repeated through the symmetry of form.  

KlingStubbins and Tocci used a similar technique to create a custom ceiling in an office building located in Waltham, Massachusetts.  Office dA, on the other hand, provided a linear solution to achieve a fluid and playful space within the interior of a restaurant in South Boston.  The design leverages the capabilities of the CNC technology to develop a carved out interior space within the wood ribs.  As the longitudinal axis emphasizes the seamless surface, the lateral views offer glimpses into the service space above.  To highlight this strategy, certain areas of the ceiling "drip" and "slump," acknowledging the location of areas such as exit signs, lighting features, and other details.  Therefore, various methods can be applied to cope with and overcome the limitations of the x- and y-axis only cuts the CNC makes.  

Project description:

Exploring the capabilities and benefits of the CNC machine in correlation with Rhino will provide a foundation of knowledge in regards to digital fabrication.  I chose to design and construct a light fixture of spherical nature as this geometry poses a challenge when constructed on a machine with many limitations.  For instance, the CNC only cuts along the x- and y-plane and through material at least 1/8” thick.  In addition, the mill is not meant for extremely detailed geometries as the bits are at least 1/8”.  Because of these limitations, I strived to design on a larger and less detailed scale.  After researching the tools in Rhino as well as the most efficient methods of modeling the desired form, I learned I needed a better understanding of the geometry I want to create.  Since SketchUp is the easiest and fastest modeling tool, I decided to quickly experiment with some shapes within that software.  I discovered a polyhedron consisting of 32 individual planes of which SketchUp aided in recognizing accurate dimensions and proportions for each plane.  These pieces were also designed to fit together through the utilization of notching, which will hold the project together without having to use glue or additional hardware.  This technique will provide the greatest strength since friction is more secure than any other type of connection.  The required thickness of the material does not allow these notches to overlap, therefore, they had to be carefully planned to work together.  After acquiring the appropriate dimensions and importing the final geometry into Rhino software, the CNC will produce the end result.  I expect the pieces to be cut accurately in order for the project to be successful.

Working Bibliography:

Autodesk. KlingStubbins & Tocci Building Companies. Retrieved April 10, 2011 from

                http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=12902887

CNC Information. History of CNC. Retrieved April 10, 2011, from

                http://www.cncinformation.com/cnc-info-cnc-information-cnc-general-info/cnc-

                machine-tool
CNC Milling. Limitations. Retrieved April 5, 2011 from
                http://www.cs.cmu.edu/~rapidproto/students.03/dwm3/project2/limitations.html

Lazerian. Borealis Lamp-Shade. Retrieved April 8, 2011, from
                http://www.lazerian.co.uk/prod-borealis.php

Saieh, Nico. Arch Daily. BanQ/Office dA. Retrieved April 3, 2011 from

                http://www.archdaily.com/42581/banq-office-da/

Sullivan Manufacturing Corporation. The History of CNC. Retrieved April 1, 2011 from
                http://www.sullivancorp.com/history-cnc.htm

Yatzer. Light Modulator by Lazerian. Retrieved April 8, 2011, from
                http://www.yatzer.com/Light-Modulator-by-Lazerian