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Chapter 3 Experimental Setup and materials 3.1 Fab at Home as a Rapid prototyping test bed Fab@Home model 1 is a three axis gantry positioning system which is powered by stepper motors. It mainly consists of: Chassis 1-Syringe Tool 4-Axis Electronics Firmware Application USB Drivers Style options These stepper motors are further attached to lead screws. The tool used for deposition is syringe based. Right on top of the syringe is a stepper motor which is responsible for the movement of the plunger and material deposition from the syringe. The electrical board provides 24 V energy to the four stepper motors. Along with this are two limit switches for each axis and an optional one limit switch for each of the axis. A microcontroller is used to control the positioning of the axes and is connected to the PC with a Universal Serial Bus connection. A graphic user interface comes with the software and also available on Fab@home‟s homepage establishes the user connection and allows the control of the machine to manoeuvre and operate the machine. The main body, structure and components of the Fab@Home machine are made from acrylic sheets which have been laser cut as per the dimension desired as per design. It uses a t-nut style fastening method, high manufacturing tolerances improves the reliability of the machine. For linear motion of the positioning system, linear ball bearing blocks of half inch diameter rails are used. The deposition tool rides on the Y axis which rides on the X axis in a gantry configuration. The z axis moves the building platform independently to the other 2 axis, this helps in minimum movement of parts while they are being made. External polymer lead nuts are 62
mounted to the axes carriage. Timing belt and pulleys are used to couple a slave lead screw to the motor lead screw to achieve a symmetrical drive in case of the x axis. A microcontroller with a universal serial bus 2.0 peripheral, the Philips LPC-2148 ARM7TDMI is used with this machine which provides the main channel of communication between the machine and the user. It is a high performance 60 MHz, flash based micro controller with 512kb flash memory and 40kb of RAM. The large Random access memory available helps to buffer motion commands so that real time motion is not affected. The universal serial bus powers the microcontroller and so communications are intact even when amplifier electronics are not powered. A xylotex 4 axis stepper motor amplifier board is used to power the syringe tool stepper motors and the positioning system. This board provides switch mode current regulation for 4 stepper motors per board. The microcontroller‟s firmware was developed in C language using a software called Crossworks. The firmware provides some very important function like Configuration of limit switches (present/absent for each axis and direction) Communicating axes positions and other system status to the PC via the USB Controlling step and direction outputs for up to 6 axes. Receiving and syntactic analysis of packetized commands from the PC via the USB Buffering of motion path segments for fabrication paths Immediate execution of jog motion and emergency stop commands 3.2 Development of Fab@Home machine The project begins with the procurement of the Fab@home kit from Koba industries, based in Albuquerque, US which essentially means that the kit contains everything required for the setup. The Fab@home machine can also be built by buying the fabber and the parts separately. Being an open source code machine and the design of the structural components and everything required is available and hence the body can also be cut to dimensions with a laser cutting machine. With a good 63
Page 1 and 2:
An Investigation into curved layer
Page 3 and 4:
Contents Abstract..................
Page 5 and 6:
3.5.2 Fabepoxy.....................
Page 7 and 8:
methodology to print simple curved
Page 9 and 10:
List of Figures 1.1 The Rapid proto
Page 11 and 12: 4.3 Parts being tested with Hounsfi
Page 13 and 14: List of Abbreviations 3D: Three dim
Page 15 and 16: Fig 1.1 The Rapid prototyping Cycle
Page 17 and 18: 1.1.1 Stereolithography Stereolitho
Page 19 and 20: The object to be made is first mode
Page 21 and 22: 1.1.5 Laser Engineered Net Shaping
Page 23 and 24: 1.2 Fused Deposition Modeling A det
Page 25 and 26: Fig 1.8 Deposition Head Different t
Page 27 and 28: 900mc is capable of producing parts
Page 29 and 30: noted that the parts built in this
Page 31 and 32: structure. Honeycomb scaffold archi
Page 33 and 34: optimal direction to build a part t
Page 35 and 36: processing treatment was analyzed w
Page 37 and 38: The actual influence of the curved
Page 39 and 40: Separating the Main part with its s
Page 41 and 42: limited to simple models. It could
Page 43 and 44: Fig 2.2 Faces, Edges and Vertices o
Page 45 and 46: 2.1.5 Constructive Solid Geometry C
Page 47 and 48: A STL file is a triangular represen
Page 49 and 50: Fig 2.8 A sample Binary STL File Sl
Page 51 and 52: Different processes may either vary
Page 53 and 54: At the very outset of generating th
Page 55 and 56: and correction of each point to sat
Page 57 and 58: apid prototyping machine are remove
Page 59 and 60: Fig 2.13 Main Part Fig 2.14 Support
Page 61: As this text file is to be used wit
Page 65 and 66: Fig 3.1 The deposition head At the
Page 67 and 68: 3.2.3 Assembling Electronics and ca
Page 69 and 70: microcontroller is now disconnected
Page 71 and 72: The relationship between test point
Page 73 and 74: on the mechanical properties and po
Page 75 and 76: 3.5.1 Silicone with other materials
Page 77 and 78: Fab@home machine. Since our require
Page 79 and 80: are printed using the two suitable
Page 81 and 82: The support structure‟s dimension
Page 83 and 84: machine Fig 3.13 Flat and curved la
Page 85 and 86: 4.1 Experimental conditions Chapter
Page 87 and 88: have many factors from contention a
Page 89 and 90: 4.3 Taguchi methods There are two t
Page 91 and 92: Such steps usually identify the nee
Page 93 and 94: Nominal is best Larger is better S
Page 95 and 96: Control of material flow - The lead
Page 97 and 98: Fig 4.3 Parts being tested with Hou
Page 99 and 100: values in all cases are almost doub
Page 101 and 102: level. The other parameters were in
Page 103 and 104: The finite element method has had a
Page 105 and 106: performance of finished FDM parts [
Page 107 and 108: ehaviour with failure occurring at
Page 109 and 110: Fig. 2 (a) is the thin curved part
Page 111 and 112: Table 5.1 Property data: Fabepoxy M
Page 113 and 114:
optimum number. The final finite el
Page 115 and 116:
Fig. 5.11 Load and boundary conditi
Page 117 and 118:
overall deflection pattern of two s
Page 119 and 120:
Fig. 5.13 Variation of compressive
Page 121 and 122:
Fig. 5.15 shows the overall deforma
Page 123 and 124:
The effectiveness of the deposition
Page 125 and 126:
[11] M. Greul, T. Pintat, M. Greuli
Page 127 and 128:
[32] Philip J. Ross, 1988, “Taguc
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