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