Author: Reese Knopp

Updates

• Guest speaker Bill Becker will present on wheels on Monday, April 20th
• Wednesday, April 22nd we will “Show and Tell” home projects
• Fusion360: work on drawing motorcycle parts for final project

Today: Guest Lecture by Professor Arnold on Material Science

Professor Arnold spoke to us about the application of materials in context and the importance of carefully thinking about the materials of individual parts.

• Carburetor
  • • The goal of a carburetor is to bring together materials that are highly reactive (oxygen and fuel), therefore the material of the carburetor must be able to withstand corrosion.
    • Made of aluminum and brass
    • Materials change over time, so using two different materials has its advantages in acting as a preventative measure against corrosion.
• Frame
  • • Braise vs Weld
      • • braising: uses multiple kinds of materials; only on surface of material
        • welding: melting metals together; penetrates into the material
    • Why use a hollow tube for the frame rather than a solid or alternative shape?
      • • the tube has the same necessary mechanical properties, and reduces weight and cost
• Brakes
  • • want a material for the brake pads that provides lots of friction, but won’t melt
    • solution: composite of ceramics and metals
      • • ceramics provide the heat resistance but are brittle
        • metals provide the ductility
    • Example of carbon brake pad material:
      • • Phenol resin (thermoset polymer), steel (ductility & even heat distribution), graphite (carbon-high temperature material), cashew (organic material-carbon)
• Polymers
  • • molecule (monomer) that repeats lots of times
    • properties can range from soft and squishy to hard and brittle
• Epoxy
  • • polymers that are very hard
    • thermoset polymer (when it reaches high temperatures it will not melt but will turn into a vapor)
    • In practice, two components are mixed together to form the epoxy. This is an exothermic process that forms a crosslink between the molecules.
• Forged vs Drop Forged
  • • changing a metals shape (by hitting, stretching, etc.) makes it harder, but the trade off is that it becomes more brittle

Chapter 4 Discussion

• Discussion leader: Jen
• Motorcycle references on pgs. 88, 89, and 94
  • • Pneumatic die grinder-air tools; gentle & high speed; commonly used for m/c
    • crank 69mm stroke; pistons to fit an 87mm bore; double-barrel carburetor; free-flow exhaust (less back pressure & higher power); centrifugal advanced distributor; remote oil cooler and full-flow filter; lightened flywheel; heavy clutch (heavier clutch = tighter spring = harder push on clutch)
• Plywood vs solid wood (in reference to rosewood plywood)
  • • Rupert: rosewood plywood is plywood with a rosewood veneer on top
    • plywood is not as sensitive to humidity changes as solid wood is
• Cecilia: connection to Zen and the Art of Motorcycle Maintenance; understanding the history of the machine through its physical alterations
• Careful vs Commanding
  • • idea presented by book: figuring out where you fit within these two categories and choosing a profession that matches those tendencies
• Anna: discussion of Aristotle’s definitions of art-those that “reliably attain their object”(like building) and those that are “stochastic” (medicine) (pg81)
• Betty Edwards and Drawing on the Right Side of the Brain

Updates:

• Bill Becker’s presentation has been moved to April 20th
• We will continue reading one chapter of Shop Class as Soulcraft per class for the rest of the semester

Shop Class as Soulcraft Chapter 3 Discussion:

• Discussion leader: Taylor- accessibility for fixing stuff independently; dependence on others vs self
• Hien – Motorcycle reference: kicker starter on early motorcycles
  • • Prof Littman:  easier to start m/c when its on center stand b/c it is more stable; it’s important to listen to the exhaust/intake in order to get it at the right point in the cycle to get the m/c started
• Hien – M/C reference: oil pump-old m/c used a hand pump rather than an automatic pump
  • • Prof Littman: oil pump was mounted on the handle bars; manual lever for retarding spark; retard fully when starting the m/c otherwise the engine could run in reverse, then once the m/c is started advance the spark; amount of advance affects the power
• Rupert – society removed option to fix things, ex) Mercedes removing dipstick; made a connection to class where we machine our own parts rather than buying them when we have the need
• Anna- discussion of music and freedom; idea founded on obedience to instrument
  • • Prof Littman: agency vs autonomy; agency = skilled on instrument, the thing; autonomy = playing radio, the application
• Anna – Greek philosophy; different levels of knowing
• Cecilia – user of technology is passive; people have to disengage with it sometimes otherwise it becomes frustrating
• Hien – easier & more intuitive = more assessable for larger audience vs keeping it specific and customizable
• Taylor – discussion of learning curves &  automatic vs manual
• Adam – pg. 68-69 what separates humans from other animals; “handiness”

Fusion 360:

• Went over how everyone is progressing with Fusion 360
• Computer Aided Engineering Analysis in Fusion360
  • • Create object
    • go to Simulation
    • click Static Stress Analysis
    • loads-> cases-> constraints->select a face (anchors surface)->ok
    • loads->select face & set magnitude->ok
    • results->solve->results->animate-> check two way & set steps

Circuit Simulator:

• http://falstad.com/circuit/circuitjs.html
• simulated ignition system (see photo library)