Monday Notes
No recap
Presentation by Bill Becker – Discovering the Motorcycle Wheel
About Bill – retired architect, worked with Littman on toy trains at Franklin Institute. Did a lot of educational work, nonprofit work. Decided he wanted to work on motorcycles after retiring, been a long interest. Lots of shop experience, loves to make things and now focuses on antique toys and building them from scratch
Looking at wheel – through lens of materials, design, and physics
Round – good geometry for moving things
1790 – first bicycle, made out of wood and radial spokes
1885 – motorized bicycle, still wooden and radial spokes but has a transmission
1895 – no longer wood, metal spokes and metal hub, horizontal motor with jack shaft, back wheel has a filler and has a brake, block of wood that pushes down onto the wheel
1960 – tiger cub – spokes no longer radial and cross and triangulate, drive mechanism that drives the rear wheel
1960 – casting wheels that replace spokes
Today – cast wheels made out of carbon fiber strong and light
What are some major forces that played a role in the evolution of the motorcycle wheel?
- Need stronger wheels because motor power
- Materials improve and become better
- Depends on the surface the bike travels on, different wheels for paved areas vs mountain bikes
- Increased speeds
One of most important factors
Weight – make lighter
Wheels have inertia, so if it is heavy it takes more work to make it move
Response to forces – better design
Turning more requires different forces esp when faster, impact forces
Technology – better machinery
Materials in wheel
Each material has unique properties
- Strength
- Flexibility
- Hardness
- Workability (how easily it can be machined, malleable and ductible)
- Resistance to corrosion
- Conductivity
- Friction
- Cost
Materials in rim – mild steel sheet, rolled into correct profile, welded, plated with copper nickel and chromium
Needs to be strong rigid, workable, resistant to corrosion, cost effective, available
Cold vs Hot while machining – if hot then it is malleable and can change shape
If you heat tempered things then immediately cool it then it makes it stronger
Copper is opposite, depending on how it is cooled it can be hard or soft
Spokes – mild steel wire
Has to be strong efficient (small amount of material), workable, resistant to corrosion, cost, available
Hub
Attached motorcycle to wheel
Needs to be light weight, conducts heat, workable, natural resistance to corrosion, cost effective, available
Needs to conduct heat as tires get hot from braking
Bearings
Extremely hard, withstands wear, reduces friction, cost effective, available
Tire
Flexible, durable, moldable, resilient, high coefficient of fraction, cost effective, available
Designers select materials based on their suitability for the task
Best performance at lowest cost = efficiency
What are the forces on our wheel?
Loads in engineering terms
- Dead loads = weight of the wheel itself and the motorcycle
- Live load = rider, passenger, gas and oil, luggage – the loads because of what we’re asking the motorcycle to do, asking it to carry passengers
- Static loads – loads when object at rest, wheels at rest – effects of gravity
- Dynamics loads – loads when moving, wheels in motion – effects of applying motor power and acceleration, effects of braking and deceleration, effects of turning the motorcycle, effects of striking an object – impact forces
Forces act in a directional manner, geometry of the wheel reacts to forces
Spokes are arranged in crosscrossing teams
Within ur teams you have 2 spokes that focus on acceleration and declaration and 2 spokes focus on side forces from turning
Loads are distributed in teams, better than radial
How do forces affect the elements within a structure?
5 basic forces acting on elements
- Compression, squeezing
- Tension, stretching/pulling
- Shear, trying to break molecular bond by cutting
- Bending, hybrid of compression and tension, middle of beam is neutral axis not affected
- Torsion
The tire is for cushioning the other elements from impact
The rim is purely compression ring that supports the tires
Spokes member the support fo the rim and the hub
Hub tension member that supports the spokes
The 20 top spokes provide tensile reaction when static
Spokes unable to hold compression by design, if compression it just pops out
The 20 backward leaning spokes provide tensile reaction when accelerating
20 right or left spokes provide tensile reaction when turning
in team
- 2 contribute to acceleration
- 2 contribute to declaration
- 2 contribute to side to side
Applying forces to an element creates stress
And the reaction to the stress is strain
Young’s Modulus – stress strain diagram
Elastic region – strain goes back, not permanent
Plastic zone – deforms
The transition from elastic to plastic is at the yield point, amount of stress it can take drops before it starts to harden itself and reaches ultimate strength before breaking
Spokes must be tuned well as tightening one spoke affects a bunch of other spokes and you need everything in balance
Wednesday Notes
Rolled threads – stronger and higher quality than cut threads
Two rollers press into a bolt and molds the threads
If overtighten a screw, it stretched instead and if tightened too much it goes past yield point
The finer your thread, the more mechanical advantage, and the more likely you are to damage it
Steel is a hard material that can be magnetizied
Soft iron – pure iron which can be an electromagnet but can’t be a permanent magnet
Recap
Wheels – prepped bearings and worked on spokes with Bill, pressed in using arbor press
Electrical – sandblasting
Clutch/Oil – started old motorcycle, ran ok, at first no spark because no lead in, more adjustments need to be made for the engine, carburetor, and the timing. Also tighten all bolts
Engine – laser cut gaskets, took out studs and wrist pin from old engine, will try to hone the barrel instead of boring it
Chapter 3
The idea of dependency
Idea of learning by doing
Autonomy vs agency
Autonomy stereo , agency is playing musical instrument
you’re at the mercy of listening to what was already made, can’t play the things you want
Ikea – following someone else’s instructions, makes it feel like you did it yourself but you are given a solution
Makes it feel like you accomplished something
Also if you can’t do it, it puts the blame on you.
Ikea, Lego, Buildabear, are selling the idea that you did it yourself
Marketing makes you want to buy more,
Not at complete liberty, even if you have 20 options you still have to pick a premade option
Hard to make your own custom things
To do things yourself takes more time than to use premade things
Power comes with agency