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4.212
Design Fabrication Design, Computation and
Computer Controlled Devices
Prof. Larry Sass Department of Architecture and Planning
MIT
LECTURE #3
The Problem?
Rapid Prototyping
Tolerance
[1]
Why rapid prototyping?
[ CAD ]
software -- Rhino -Microstation -
hardware
Autocad
FormZ
[ CAD CAM ]
Glymph/Shelden Kolarevic Burry
software -Catia - Unigraphics -SolidWorks -ProEngineer
NC hardware -Plasma cutter - NC milling -NC routing -Waterjet Cutting
[ why rapid prototyping? ]
1. visual representation
2. relationship between building methods and simulate performance
3. allows for the study complex design possibilities
Issues
should the process reflect the design problem?
can the first cut be the last cut?
research project
Rapid Prototyping continuous curved surfaces models
summer, 2002
[research observation ]
The Experience Music Project Architect: Gehry Partners
- CAD CAM manufactured surface and structure
- overlapping surfaces
- surface is a rain screen
[research question ]
- can curved surfaces be modeled in a design office?
- is it possible to have a continuous surface with no overlapping parts?
- can the surface be waterproof?
- does a rapid prototyping process reflect methods used in the field?
[ create surface ]
[ sub-divide surface ]
[ mold blocks ]
[ mold blocks ]
[research results ]
Simulation of a Continuous Glass Surface
1. Introduction of the hand was cause for a high number of surface errors
2. Visually correct position of surface components
3. Inconsistent connections at joints
4. Plastic had a hard time during double curving
[field example of inconsistant surfaces manufacturing]
Graz Museum Architect: Peter Cook
- CAD CAM manufactured surface and structure
- no overlapping surfaces
- surface is a rain screen
[observed results ]
Simulation of a Continuous Glass Surface
1. Introduction of the hand was cause for a high number of surface errors
2. Visually correct position of surface components
3. Inconsistent connections at joints
4. Plastic had a hard time during double curving
[recommendations ]
Continuous Glass Surface
A. Full CAM or RP process
B. Molds and Cuts in one process
[ CAD ] [ CAD
software -Catia ---ProEngineer
-Plasma cutter - NC milling -NC routing -
software -- Rhino -Microstation -
hardware -Paper camm -Laser Cutter -- FDM -
Waterjet Cutting
rapid prototyping
CAM ] nc tools
Unigraphics SolidWorks
NC hardware
Autocad
FormZ
3D Printer
Stereo Lithography
[ why rapid prototyping? ]
1. visual representation
2. relationship between building methods and simulate performance
3. allows for the study complex design possibilities
[2]
Rapid Prototyping
[recommendations ]
Rapid Prototyping Devices
Addition (building)
Subtraction (cutting)
Devices Goals
Rapid Representation vs Manufacturing
Visual and Usable representations
Design Models Buildings
CAD CAD
Rapid CAD CAMPrototyping Devices
z
Building Devices
-3D Printer - Metal - Cornstarch - Plaster - Ceramics
- FDM - ABS Plastic - Rubber - Wax
-Stereo Lithography - Resin
ZCORP
-3D Printer - Metal - Cornstarch
-Plaster - Ceramics
Build
Feed
Slow Axis
ZCORP
Overflow
Binder and Head
Build
Slow Axis Roller
Feed
ZCORP
Open Spaces
Plaster
-3D Printer Advantages- Speed
- Self Supporting
- Low Cost
ZCORP
-Disadvantages
- Low Strength
- Required Post Processing Wax
Plaster
Strata Sys
-Fuse Deposition Modeling - ABS Plastic - Rubber - Wax
Material
Support
Head
Envelope
Temperature Gauges
Control Board
Envelope
Z Table
z
Head
Support
Material
Material
Support Base
Heating Elements
Tips
Drive Wheels
Filament
-Advantages- Strong
- Minimal Post Processing
STRATASYS
-Disadvantages - Slow
- Porous
- Hates Voids ABS Material .010
- High Cost to Operate ABS Support Base .010
Power Supply
Stereolithography
Mirror
Mirror
Table & Polymer Vat
Laser Source
Models
Vat
Table
Laser Source
Skimming Knife
Mirror
Table & Model
Vat of Polymer
STRATASYS
-Disadvantages - Cost
- Hates Voids
- High Cost to Operate
-Advantages - Strong
- Minimal Post Processing
- Supports very thin parts
[3]
Tolerance
Tolerance
- All Materials in Components Vary
- Range of acceptable tolerances
-All elements do not need to be of a fine tolerance
Tolerance Classifications
- Material Tolerance - Cutting
-Assembly Tolerance
Natural Features of Rapid Prototyping Devices
- Tight tolerances
-Self Assembly
-Can hold shape relationships
1/8”
1/4” 1/32”
1/16”
Tolerance
- Tight Fittings for fast model assembly
- Control of complex angles and assemblies