Mechanisms, Fabrication, and Crash Course Tips Zoe Klesmith & Ana Schauer With much appreciation to Kyle Saleeby, Dr. Rich Simmons, Dr. Tom Kurfess, Dr. Chris Saldana, and former Head TA C.J. Adams Some content based upon material created by: Dr. Andrew Semidey & contributions from Alexis Noel and Hannes Daepp ME2110 | Spring 2020
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Mechanisms, Fabrication,and
Crash Course TipsZoe Klesmith & Ana Schauer
With much appreciation to Kyle Saleeby, Dr. Rich Simmons, Dr. Tom Kurfess, Dr. Chris Saldana,
and former Head TA C.J. Adams
Some content based upon material created by: Dr. Andrew Semidey & contributions from Alexis Noel and Hannes Daepp
ME2110 | Spring 2020
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This Lecture
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Crash Course:1) a rapid and intense course of study
2) an experience that resembles such a course--Merriam-Webster Dictionary
❖ ME 2110 projects are time consuming – Ideas must work– Construction must be feasible with available tools– Construction needs to be well executed
❖ Choose tools to match your skill set – aim to make manufacturing efficient & error-free– Design for Manufacturing– Invention studio tools expand fabrication capability, and can
improve quality and efficiency
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CAD and Conceptual Design
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❖ Locate and orient subsystems and parts❖ Enhanced visualization❖ Fast concept generation by combining existing
concepts❖ Documentation (version control)❖ File sharing for co-operation and communication❖ Detailed design can proceed from conceptual models❖ CAD models easily evaluated with engineering tools
(e.g. FEA)❖ Leads directly to rapid prototyping processes for
fabricating parts (Invention Studio)Adapted from: E. Bamberg, "Principles of Rapid Machine Design", 2000.
Why incorporate CAD in your design process?
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Risks and Drawbacks with CAD
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❖ Biggest Drawback: Loss of hands-on experience❖ Need to make sure concepts are physically realizable❖ Limiting assumptions can stifle creativity❖ Cannot test unmodeled effects or validate assumptions❖ Physical tests can lead to lots of learning
You need to balance Physical Testing with the Design Process and CAD
❖ Basic LED Feedback – Built-In LED status / state indicators– On / off combinations– Flashing protocol
❖ Advanced LED Feedback– External LEDs connected to MyRio/Arduino (add resistors!)– External LED / LCD screen (digikey, adafruit, sparkfun)
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Selectable Functionality
❖ [Don’t] Live programming of MyRio/Arduino– Modifying code each round– Re-uploading code for different home zone– Drop your computer in the competition
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Auxiliary Sensors
❖ [Do] Check out other sensors!
❖ Light-sensitive diode❖ Ultrasonic range finder❖ Potentiometer, encoder
• Match nut to thickness of material• Make sure washer size is sufficient• Wide-head bolts are better• Consider which tools are readily available to you
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Rapid Prototyping – Waterjet
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How does it work?• 50,000 PSI with garnet• Accuracy of 80 microns• Can cut through 6 inches of steelWhen to use waterjet:• 2D cuts of most materials
• Wood, metal, plastic
When NOT to use waterjet:• Cutting soft woods, glass, foam
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Rapid Prototyping – 3D Printers
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How does it work?• FDM, SLA, SLS, DLP• FDM accuracy 150 microns • Uses PLA (other materials available)When to use 3D printers:• Complex 3D geometries
When NOT to use 3D printers:• To make boxes• To make 2D shapes
For more general tips and guidelines, see:https://www.3dhubs.com/knowledge-base/3d-printing-stl-files-step-step-guide
❖ Building without a plan (‘cut and try’)– CAD first!
❖ Assembling skewed or slanted frames❖ Fasteners that must be tightened 'just right’❖ Using duct tape as a fastener❖ Not modifying mousetraps❖ Overuse of string
– String tangles and snags– Requires proper management to be used effectively
❖ Forgetting to regularly inspect and maintain your machine
❖ Motor/Actuator coupling and mounting– Hot glue is not a motor coupling
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Common Fabrication Mistakes
❖ Not considering the trade-offs: when does it become worth it to purchase a component rather than manufacture it in-house?
❖ Waiting until the last minute to use equipment - there can be a long queue for printers/laser cutting
❖ Not testing multiple times❖ Design fixation: don’t get stuck on a design just
because you’ve spent a lot of time on it already❖ Gears not meshing/inappropriate gear ratio
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Summary
❖ Use mechanisms to achieve capable designs– Use materials that are appropriate for desired properties (strength-weight
ratio, friction, etc.)– Constrain mechanisms to achieve reliable performance– Re-purpose household items to match functionality
❖ Select materials that are easy to work with– Low quality materials mostly produce low quality results
❖ Choose an efficient, straightforward primary manufacturing strategy that matches your experience & skills– Most foolproof manufacturing methods do not rely heavily on manual skills:
waterjet, laser-cutter, 3-D printer, CNC, etc.
❖ Plan & design your device layout & construction thoroughly– Design for Manufacture, Design for Assembly, Design for Disassembly– Secure & store all components in a well-defined device location– Use strain relief (secure wires) to avoid loose electronic connections– Remember that design is iterative: prototype and test thoroughly
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Appendix:Good Examples
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Good Examples: AXE (Fall 2019)
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Good Examples: AXE (Fall 2019)
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Good Examples: A Few Loose Screws (Spring 2016)
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Good Examples: Blue’s Clues (Spring 2015)
❖ Chelsea SilbergliedArmaan VeljiOpeyemi Olaleye
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• Constructed primarily from 2-D laser-cut plywood components• DFA/DFD: Slotted parts assemble/disassemble easily; reinforced with screws &
brackets as necessary• Result: Ability to minimize manufacturing effort - majority time spent in planning
& design (CAD), and testing• Performance: 4th round (within top 30/74)
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Good Examples: Top Gun (Spring 2015)
Chris Healy, Zach Archbold, Randy Long, & Sahas Singh 57
Sidewalls for secure storage, boxing, & aesthetics
Quality materials & assemblyGood usage of space & absence of hair triggers
Laser-cut precision components: storage shelf, side walls, & victim pusher
Clean decals for simple visual appeal
• Performance: 4th round (within top 30/74)
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Good Examples: The Shady Mammals (Summer 2015)
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Hoang Dang, Andrew Hanna, & Reagan Wilkerson
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Good Examples: The Shady Mammals (Summer 2015)
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•Performance: 1st Place
Victim RetrievalLinkage
Rubble SweepingLinkage
Weight with Pulley System
Motor 1 (Wheel and
Axle)
Motor 2 (Spur
Gears)
Constraints (Pivots and Support)
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Good Examples: Ghost Squadron (Fall 2015)
William Neidecker-Gonzales, Hannah Orr, Abheer Bipin, & Darren Maguire
• LED display for aesthetic appeal• Waterjet use for metal components• CAD: Cardboard-Aided-Design
Example: Torpedo deployment arm1. Prototype in cardboard & test2. Trace/Modify in CAD package3. Manufacture (e.g., waterjet, lasercut)4. Assemble & run
Performance: 3rd Place
1/2
1/2
3/4
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Good Examples: WoodFellas (Fall 2015)
• Example of good planning & great carpentry skills
• Tools: table saw, drill press, waterjet, metal shop, general assembly
• Secure location for ALL components (use provided mounting holes if possible)
• Avoid fabricating necessary/important parts if they are hard to make and affordable elsewhere (e.g., some gears are cheap on Amazon)
• Design with construction in mind (DFA)• Use structural cuts (e.g., Dado cut)
• Performance: 2nd Place
Robert Lineberg, Nolan Hall, Jason Hunyar, & Shen Yoon
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Good Examples: Average Joes (Summer 2016)Reed Morris, Kyle Brantley, Nick Maniscalco, & Alex Ullrich
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Good Examples: Average Joes (Summer 2016)
• Laser cut parts provided:Precision Spare partsAbility to make mirrored subsystems
• Minimized snag/rough points for all string driven systems
• Used manual prototyping / rough builds to validate concepts, then created CAD models to produce final parts
• Performance: 1st Place and Best In Show 63
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Laptop
Arduino &Electronics
Mounting PlatformAmigoBot Base
Air Supply
Launcher & Reloading Mechanism
Camera
Non-ME 2110 Example: Ramblin’ Wrecking Bot
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Non-ME 2110 Example: Ramblin’ Wrecking Bot
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Mechanical Design & Construction
❖ Primarily laser-cut plywood and 3-D printed parts
❖ Launching Mechanism– Solenoid valve attached to PVC
pipe– Servo-actuated gimbal provides
2 DoF
❖ Reloading Mechanism– Servo-controlled barrel– Custom laser-cut plywood parts
with 3D-printed spacers/braces
❖ ME2110 Projects have different requirements – use resources wisely