1. Chris D. McCoy| Berkeley Mechanical Design
1| Design Brainstorm
Overview of project
Goals of Project
Include:
Preliminary sketches / pictures to aid discussion
Design Criteria:
Must Haves
Should Haves
Nice to Haves
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design

2. Chris D. McCoy| Berkeley Mechanical Design
2| Design Review
Include:
Current Design Issues
Relevant Calculations
CAD / Design Layout Images
Modeling
What questions do you want to have answered?
Etc.
Design Review Goals:
To make any last minute needed design changes
Build confidence that your design is complete and ready for sourcing / fabrication
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design

3. Chris D. McCoy| Berkeley Mechanical Design
3| Design Reflection
Include:
Final design (CAD)
Final Design (physical images)
Test results
Etc.
What worked / What didn’t work
Best feature of design
Worst feature of design
What did we / you forget?
Reflection Goals
Figure out how we can improve for future designs
What are people most proud of
What did you learn from this experience?
What would you do differently next time?
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design

4. Small scale engine dynamometer
Case Study #1
Small scale engine dynamometer
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design

5. 1| Design Brainstorm: 31 Jan 2008
Overview of project:
Need a robust, precision aligned, dynamometer to measure output mechanical power of a small scale hobby engine
Research will include the testing of several liquid fuels with engines at high temperatures, moderate vibration, etc.
Goals of Project
Buy or build a dyno that can measure power, torque, temperature, etc. in a timely fashion
Design Criteria:
Must Haves
Low cost
Precision alignment of engine shaft to electric motor shaft
Ability to start engine / measure power
Adjustability / flexible
Fit on test bench
Should Haves
DFA - Easy to disassemble
DFM
Nice to Haves
Easy to machine
Quick lead time
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design

6. Chris D. McCoy| Berkeley Mechanical Design
2| Design Review: 26 Feb 08
Include:
What material is resistant to fuels?
How do I achieve precision alignment?
Where should I have this machined?
What else should I consider?
What am I forgetting?
Design Review Goals:
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design

7. 3| Design Reflection: 1 Sept. 2008
Total cost: ~$
What worked:
Output power and torque can be measured well
What didn’t work:
Design for assembly / disassembly could have been improved. More room for tools (socket sets / allen keys)
Use all English screws and hardware. Machinists prefer it and it’s easier/cheaper to find hardware
Starting engine w/generator was tricky (in terms of speed controller usage)
Best feature of design: Quick adjust / removal for engine mount
Worst feature of design: Torque measurement arm– too much vibration, very noisy, consider cradle dyno for the future.
What did we / you forget / not consider?
Holes for screw access w/tools (easy post modification in machine shop)
Methanol degrades Aluminum Oxide (according to internet)
Dynos on this scale CAN be purchased from Magtrol
Consider lift hooks / handles to remove slip fit / heavy components
Forgot cooling ducts
Add wire routing guides (for stress relief)
Don’t design in 4-40 or M3 tapped holes (breaking taps)
Final images
Magtrol dynos
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design

8. Interested? Need Help? Contact
If you’d like to participate or need help with a mechanical design – please contact me at:
If this PPT was helpful could be improved, please let me know!
11/12/2018
Chris D. McCoy| Berkeley Mechanical Design