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Group 2 | SLS 3D Printer Introduction
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
http://www.arptech.com.au/slshelp.htm
Additive Manufacturing- Rapid CAD to 3D Object- Made of successive 2D layers- Prototyping benefits to many industries
Methods- Stereolithography (SLA) >$5000- Fused Deposition Moulding (FDM) >$500- Selective Laser Sintering (SLS) >$10000
Selective Laser Sintering
http://news.noahraford.com/?p=1495
Group 2 | SLS 3D Printer Problem Formulation
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
There Exists a Need for an Economic SLS 3D Printer for:- Additive manufacturing research- Material scientists- Education institutions- Small businesses- Hobbyists
Develop an SLS 3D printer with comparable cost and performance to small-business FDM 3D printers currently on the market
Problem Statement:
Design Criteria:- Completely safe- Ease of Construction [hrs]- Cost [$]- Accuracy of +/- 0.5 [mm]- Print Speed [min/part]- Weight [kg]
Criteria SafetyEase of
Construction
Cost Accuracy Speed Weight Total Rank
Safety 1 1 1 1 1 5 1
Ease of Constructio
n0 1 1 1 1 4 2
Cost 0 0 1 1 1 3 3
Accuracy 0 0 0 1 1 2 4
Speed 0 0 0 0 1 1 5
Weight 0 0 0 0 0 0 6
Print Material:- Chocolate
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Potential Solutions
StationaryLaser
TranslatingPowder Box
XY Gantry
Aluminum Plastic Wood
CO2 Laser Laser Diode
Pan/Tilt Mirror
Optical Lens Adjustment
VerticalAdjustment
Cylindrical Roller
Wedge Slider
RadialDispensing
Subtractions SolutionsFrame Material
Safety Enclosure Fully Enclosed Laser-safe Plexiglass
Laser Type
Laser Positioning
Powder Transferring
Laser Diameter Adjustment
Temperature Control Thermo Electric Cooler (TEC) Fan
Group 2 | SLS 3D Printer Alternative Designs
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Criteria Safety Ease Cost Acc. Speed Weight Total
Weighting Factor 100 90 70 60 50 40
Design 1 4x100 = 400
5x90 = 450
5x70 = 350
5x60 = 300
8x50 = 400
4x40 = 160 2060
Design 2 6x100 = 600
7x90 = 630
6x70 = 420
6x70 = 420
7x50 = 350
6x40 = 240 2660
Design 3 9x100 = 900
8x90 = 720
8x90 = 720
8x60 = 480
6x50 = 300
7x40 = 280 3240
Design 1 Design 2 Design 3WoodFull EnclosureLaser DiodePan & TiltCylindrical RollerTEC
PlasticPlexiglass EnclosureLaser DiodeXY GantryWedge SliderTEC
AluminumFull EnclosureLaser DiodeXY GantryRadial WiperFan
Decision Matrix
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Mechanical Systems
1. Frame2. Electrical Enclosure3. Powder Beds
4. Radial Wiper
5. Laser Gantry
6. Screws/Bolts
7. Walls
QuickTime™ and aCinepak decompressor
are needed to see this picture.
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Powder Beds
Two linear stepper motors
Oversized feed bed
Seal around moving box base
Top View
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Radial Wiper
One servo motor
Radial slot guideway
Access powder wiped into drawer
QuickTime™ and aCinepak decompressor
are needed to see this picture.
Top View
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Laser Gantry
QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.
Capstan Roller MechanismLaser
Laser Translator Two stepper motors8mm diameter rods
4 linear bearings in laser mount
Top View
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Laser Gantry
ResolutionStepper Motor Step Resolution = 1.8o or PI/10 [rad]
Roller radius = 4 [mm]
x = r * θ
x = 0.126 [mm/step]
XY resolution of 0.126 [mm]θ X
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Electronic Enclosure
Power Supply
Arduino
Motor Drivers
Cooling Fan
Vent
Top View
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Frame and Walls
Fully enclosed for laser safety
LCD screen (debugging and process status)
Drawer to collect access powder
Hinge lid
1/8” aluminum sheet walls
8020 aluminum T-slot beams
Top View
Radiation Heat Transfer
Rate of heat transfer to powder directly determines print
timesChocolate crystal structures melt at 45oCSpectral absorption and emission of chocolate withdiffuse grey assumption
α = ε = 0.85
Incident radiation G involves chocolate absorptivity and
laser output power [W/m2]
Differential volume is heated by:
Q”rad = m * Cd * dTemp
Heating chocolate from 20oC to 45oCCan calculate Time vs Q” (laser power) to heat a
givenvolume of chocolate
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Laser Heat Transfer
http://www.ebay.com/itm/2W-445nm-M140-Blue-Laser-Diode-in-Copper-Module-W-Leads-Three-Element-Glass-/170892986250?ssPageName=ADME:X:RTQ:US:1123
http://www.engineeringtoolbox.com/radiation-heat-transfer-d_431.html
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Print Time
Print area of 10,000mm2 was considered
2 Watt laser considered due to availability
10,000 [mm2] layer area * 1 [mm] thickness / 200[s] = 50 mm3/s (estimated)
Using a 2W laser, find time to print a solid hockey puck:
Example
Volume = 113,411.5 [mm3]
113,411.5 [mm3] / 50 [mm3/s] = 2,268 [s], or 38 minutes
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Power Flow Chart
SUN Power SupplyOutput Voltage: 12V DCMax Current: 15.0AMax Power: 180W
Part Qty Voltage [V] Current [A] Power [W]Laser Diode 1 12 1.1 13.2
Gantry Stepper
Motor2 12 0.48 11.52
Powder Bed Stepper
Motor2 12 0.48 11.52
Arduino MEGA ADK 1 12 1 12
12VDC Supply 1 12 3.06 48.24 Tota
l
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Power Flow Chart
12VDC Supply 1 12 40.2 48.24
Cooling Fan 1 120 0.14 16.8120VAC
Outlet Supply
65.04 Total
Group 2 | SLS 3D Printer Software
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Pull instruction from USB
On G1 code: - Calculate X,Y step
frequency- Call XY gantry step
function. On Plane change- Turn off Laser- Call Z-Step function- Call Powder Swiper function- Turn on Laser
Main Loop
System Overview
Main Loop
Read Function
Z Step Powder Swiper
Laser ControlGantry Step
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer SkeinForgeSTL Model
facet normal ni nj nkouter loopvertex v1x v1y v1zvertex v2x v2y v2zvertex v3x v3y v3zendloop endfacet
G-Code
SkeinForge
http://www.thingiverse.com/thing:3930
http://www.thingiverse.com/thing:3930
Goal is to maintain a diagonal constant speed, so x
and y movement follow the path.
Speed is limited by melting requirement of laser
Achieve constant speed with discrete steps offrequency x and y for respective directions
Timer and Interrupt Libraries
TimerOne.h and Interrupt.h are available for use
Arduino Mega has 4 timers available for general programming2 allocated to XY Gantry1 allocated to Z Stepper
Modulate frequency using SetPeriod() function
Call Xstep ISR every pulse from timer
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Stepper Functions
θ = atan2(y1 - y0, x1 - x0)d = (x2 + y2)1/2
Stepper Logic
vstep = vmelt / resfreqx = vstepcosθfreqy = vstepsin θt = vmeltd
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Data Transfer
Need a method to transmit g-code data to Arduino Board
SerialRequires constant connection to computer, communication
overhead to ensure data transferRequires application on computer to feed arduino code line
by lineAllows for feedback from printer by passing data back
USBArduino 2560 Mega ADK (Android Development Kit) has USB
port for communicating with external devices as a masterLess communication overhead as only 1 application will
access dataUSB Host Shield github repository provides library
max3421e.h for Mega to read/write to USB port
USB is preferred to minimize data transfer delays and lack of external PC requirement.
Serial will be used during debugging for feedback from printer
Communication: Serial vs USB
Gantry: 1. Cable DriveUS Patent # 4957014, April 10, 1989Edward F. Burke
2. Ilan Moyer http://web.mit.edu/imoyer/www/portfolio/foamcore/
SLS Printing: Method For Producing 3D ObjectUS Patent # 8187522, May 29, 2012Yoshikazu Higashi, et al.
Radial Wiper: No Patents Youtube video: “quadraturencoder” http://www.youtube.com/watch?v=YBqUOP-MA1Q&feature=plcp
SoftwareSkeinforge is copyrighted under GNU Affero General Public Licence, allowing it to be freely distributedNo other significant software in design is worth patenting or has been patented
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer Patents
Andy Vopni Benjamin Cousins Brian Luptak Nima Majidifar
Group 2 | SLS 3D Printer ReferencesARPTECH - Rapid Prototyping Services, http://www.arptech.com.au/slshelp.htm, Oct 13th, 2012
Burke, Edward. Cable drive geometry. http://www.google.com/patents/US4957014?pg=PA3&dq=4957014&hl=en&sa=X&ei=vaqpUMQ0icTbBbmugKgO&ved=0CDcQ6AEwAA#v=onepage&q=4957014&f=false, Nov 18th, 2012
Engineering Toolbox, http://www.engineeringtoolbox.com/radiation-heat-transfer-d_431.html, Nov 18th, 2012
Higashi, Yoshikazu. Method and apparatus for producing a three-dimensional object, and three-dimensional shaped object. http://www.google.com/patents/US8187522?pg=PA10&dq=8187522&hl=en&sa=X&ei=RZipULPDIejhygH27ICQBw&ved=0CDQQ6AEwAA#v=onepage&q=8187522&f=false, Nov 18th, 2012
Ilan Moyer, http://web.mit.edu/imoyer/www/portfolio/foamcore/, Nov 18th, 2012
Introduction to Thermal Systems Engineering, http://ca.wiley.com/WileyCDA/WileyTitle/productCd-0471204900.html, Nov 18th, 2012
M140 Blue Laser Diode, http://www.ebay.com/itm/2W-445nm-M140-Blue-Laser-Diode-in-Copper-Module-W-Leads-Three-Element-Glass-/170892986250?ssPageName=ADME:X:RTQ:US:1123, Nov 18th 2012
Noah Raford, 21st Century Strategy, Policy and Design, http://news.noahraford.com/?p=1495, Nov 18th, 2012
Thingiverse, 120 Film Advance Crank http://www.thingiverse.com/thing:3930, Nov 17th, 2012
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