Month: April 2019

Recap of Last Week’s Lab

• Detailing: Primed the oil and gas tank, they are painting today.

• Frame: Got the seat done!

• Wheels: Finished one of the wheels with Bill Becker.

• Top-End: Finished assembling the carburetor, fixed the exhaust pipe, and put the blue bike back together.

• Bottom End: Didn’t put in the sprocket, therefore had to unseal the case again and put it in.

• Electrical: Drilled hole in the case cover then re-attached it back on to the bike and tested it.

Representation:

• What happens to the rear wheel when you just accelerate? What happens to the tension in the chain? The tension goes up on the top.
• Spring arm allows the whole wheel to bounce up and down.
• Braking locks the hub and causes the whole assembly to twist.
  • If not designed well, it will snap. In a previous year, it snapped (due to large stress). Glen drew the part and 3D printed it. Then, manufactured it out of high steel aluminum.
• Another year found that the last gear on the lay shift is missing a tooth. Believe it case hardened.
• Involute curve:
  • It has the property, when the gears are matching, one tooth rolls on the other. By having the right shape, you have a low mechanical loss. Sliding causes friction loss.
• Friction
  • Clutch plates
  • Coefficient of friction
    • F = (Mu) * N
      • F = force of static friction.
      • Mu = coefficient of static friction.
      • N = normal force.
  • To calculate theta, the coefficient of friction.
    • Mu = tan(theta)
• Friction is important in the motorcycle, without friction motorcycle would not go.

• Architect. Currently, in retirement, restoring motorcycles.
• He read a book about how kids draw wheels. It was just lines. It looked stupid, yet that is how wheels were previously made/looked.
• Mass – how the matter in things reacts to forces. Particularly, the mass in other objects.
• Inertia – how the mass reacts to moving (stopping and going).
  • Scooter/bike have less mass in the wheel.
  • Motorcycles are performance-based vehicles. Many times, they are for sports too. You want them to be as light as possible, strong, and overcome inertia quite easily.
• The forces that act on a wheel:
  • Gravity (weight), velocity (magnitude of speed), orientation (the direction you’re going towards)
    • Vectors (a simple way of saying the direction of force):
      • Helps you analyze how the force is moving in that system.
• Materials:
  • Most motorcycles have aluminum hubs or rims.
  • Cast iron in hubs.
  • Mild steel you can see in stamping, and the rim is stamped out of mild steel.
  • Hardened steel in ball bearings.
  • Stainless steel in spokes.
  • Rubber in a tire.
  • Polyester in a tube.
  • Brass in the nipple of air in the tube.
  • Chromium in paint so it does not rust.
  • Asbestos in brakes (not today).
  • Plastic in the retainer of bearing.
  • Air

• Pick materials based on what you want the material to do, but it has to be designed to withstand whatever loads they are subjected towards.
  • Dead load: simply the weight of the object itself. Being subjected to the forces of gravity.
  • Live load: the driver, passenger, luggage, etc.
  • Static load: the weight not in motion, just sitting there.
  • Dynamic load: loads in motion. Example: Hammer’s head.
• The geometry of the wheel:
  • Compressive force: mass causes something to be squeezed.
  • Tension: opposite of compressive.
  • Bending: only compression and tension.
  • Sheer: separating the atomic structure within the material causing it to rip.
  • Autonomic structure of the material is holding the neutrality. There is a neutral axis down the middle.
• Young Modulus was a physician. He wanted to know why materials behaved the way they do. He discovered a relationship between force you put on a material (stress load) and how it reacts. Strain is the reaction to stress. When you put the material under stress it will react in strain through deformation. It gets to the point where it approaches its yield point, goes through a deformation, then fails. Example: rubber band.
• The rotor forces action on a wheel.
  • Forces are being applied to the hub (in tension) and are being transmitted to the wheel, then to the rim (in compression) through the spokes. Spokes can’t transmit a force, because it is a triangle, it is able to pull the rim around. Therefore, we talk about the forces flowing through the spokes. Spokes are in tension. The more load you put on it the straighter it gets. Effective by the virtue of it its number. Contribute to the strength of the wheel. (Now, they are casting.)
• Dynamic loads from turning.
  • When you start to load sideways. What do you think is happening? Who is doing the work?
    • Compression on one-side and tension on the other.
• Work the spoke is capable of doing.
  • 8-inch diameter for 6900 psi – holds up about 860 pounds by itself.

Recap of Last Week’s Lab

• Detailing: Flushed out the oil tank with motor cleaner in the hood. They sanded down the gasket.
• Frame: Worked with Computer-Aided Design, CAD, to work on a piece that connects the seat to the board.
• Wheels: Discovered paint inside one of the wheels (apparently, it is insignificant). They went through the catalog and found the ring they needed (a backup ring for keeping the grease in), and they plan on pressing in the bearings today.
• Top-End: Attached the cover to the motorcycle. Plan on looking for carburetor parts, work on the fuel line and, possibly, put in some gasoline.
• Bottom End: Worked a bit on sealing, they cleaned out the oil pump area. They pressed the bearing in too much, but they fixed it (by tapping it farther out).
• Electrical: Worked on the Red Motorcycle. They re-cabled the clutch cable after shorting it twice. Today, they are working on the cover.

Reading Discussion

• Discussion Leader: Agnes
  • The “winners” (like the Olympic champion) is the one with intrinsic motivation. Page 180.
  • There is a disconnect between work life and leisure life. Page 181.
    • The bike shop can be a place where you find the two merges into one. Page 182.
  • Face-to-Face interactions offer a community when the political/brand image is no longer there. I.E. “German-Made.” Page 189.
  • Any job that can be scaled up, depersonalized, and made to answer to outside forces can be degraded. Page 198.
  • Failure is important. Page 203.
    • People in charge should know what it is like to fail.

Feedback regarding the readings.

• Pirsig’s book is hard to read.
• Shop Class as Soulcraft seemed more relevant.
  • Read it first.
• The text would be more difficult to engage with if it were to be just motorcycle references.
• Books complement each other.

Brake dynamometers

• Last class, we measured torque vs. speed.
• The drum has a moment of inertia.
  • F = m * (v-dot)
  • Put torque in a wheel, drum speeds up.
  • J = moment of inertia.
• To figure out the force on the object:
  • M*G = force of gravity
  • If you let it go, it accelerates.
  • Velocity increases linearly in time.
  • The derivative of V(t) is acceleration.
  • Can graph torque as a function of angular speed

A quick look into the history of Princeton (sparked by the discussion of some Orange Key members):

• Joseph Henry’s House.
• The Henry Motor.

Recap of Last Week’s Lab:

• Detailing: Reattached the seat on the blue bike. Used S.A.E.
• Frame: Started to assemble the frame and used Computer-Aided Design (CAD) to design a washer.
• Wheels: Spent last class adjusting the offset of both wheels.
• Top-End: Built the head. Professor Littman and Jon got the rockers in, during their own time.
• Bottom End: Cleaned up the rest of the parts. Today, they plan on spending some time on the blue bike, checking oil levels, and ensuring the carburetor is attached.
• Electrical: Cut the clutch cable again (because the first cut was too long). They drained the oil. They took the cover off to drill a hole, so to make tightening the threads easier. They plan on drilling the hole today.

Reading Discussion:

• Discussion Leader: Charles
  • With Emotional Intelligence, the whole person is at issue, rather than a narrow set of skills. Page 129.
  • The author worked at IAC, where he wrote journal abstracts. He believed the lack of an external, objective standard resulted in him despising his job. Page 135.
  • Credential Inflation and pushing everyone into college will require a janitor to hold a PhD. Page 143.
  • Difference between Crew vs. Corporate Culture:
    • With a crew, you have proof of your own worth independent of others.
    • Air Traffic Controllers who do not have formal education perform better than their college-educated counterparts.
  • Tacit knowledge comes from recognizing patterns. Page 166.
  • Technical writers need to be mechanics. Page 179.

Motor demonstration:

• There is rope wrapped around a pulley (turning counterclockwise). When the rope is loose, there is no load. The load cell measures the tension in the rope.
• When you take the difference in tension between the upper rope and lower rope and multiply by the radius, you get the brake.
• Graphed two things:
  • torque vs. speed
  • power curve (peaked at half of no-load speed).

Lab Recap:

Bottom End: Started trying to find all the pieces for the new engine based on the 1964 Mountain Cub. A lot harder than expected because they didn’t have the right handbook.   Keeping record of stuff that they do and don’t have.

Detailing: Put the oil tank back on the bike.

Electrical: Figured out where to snake the clutch cable. Trying to cut the cable. Difficult because we have to cut down on the actual cable, but also the distance between the wire and the cable jacket

Top End: Sandblasted the head. Last class grounded the valves, and this class couldn’t find them.

Frame: Light sanding and another coat on the fork tubes. Brought the swing arm down to Glen, and it turns out it’s missing a washer.

Wheels: Process figuring out how to lace up the wheels. When a wheel turns, it should turn straight up and down and not wobble left to right.

Chapters 2 and 3

Summary: Simplification of blue-collar work led to less agency, and degradation of intellectual aspect. New idea in early 20th century, brought about by Ford assembly line. Using a cost-efficient low skilled laborer and automated process turned craftsmen to blue-collar workers. He also raised worker wages to reduce worker turnovers. He had prizes for workers who identified ways to cut costs. White-collar work just became the intellectual version of blue-collar work. Rise of the creative class – employed to think of ideas and not do much else. To be creative, you first need to have an understanding of the form and function of something. Need to have a discipline that underlies it.

Motorcycle References: Evolution of oil on your motorcycles. Repeats issue of engines with no more dipsticks.

Modern Manufacturing:

FDM (fused deposition manufacturing) and CNC mill, die cutter

SLA

water-jet (water has pieces of garnet)

EDM (electric discharge machine)

plasma cutter

All of these things are now driven by computers (print function)

Lab Recap

Bottom End: Put engine back into the frame. There were scratches on the surface, which is a problem with the sealing. It is a problem because of air leaking out or gas leaking in. It was sent down to the shop.

Detailing: Gas tank and headlight back on the frame of motorcycle. Still need to put in the carburetor.

Top End: Cut the valves. The angles were cut at 30, 45, and 120 degrees. Glen put a drill on the shaft and spun it, instead of using the suction cut device. Used a three angle cut. When the valve sits in the seat, it hits the middle of the seat. Used bluing compound to find the surfaces the valve touches the valve seat. Seats were hardened, cast iron. Seats and valve have to be gas tight.

Frame: Painted more coat on the fork tubes. Will start working on the swing arm.

Electrical: Redoing the clutch cable on the red bike and modeling it after the green bike. The clutch cable was too long and so wasn’t kickstarting efficiently. When routing the cable, want to avoid sharp kinks because this leads to non-smooth draw and release.

Wheels: Working on lacing up the wheels and found out the phalanges were matched with the wrong hub. Looked in the past at the rim to figure out the large phalange and the small phalange. Possible that the previous decision as wrong. Spokes were going all the way through the nipple, and professor was concerned that that would cause a problem on the nipple/nut. The shaft diameter was not 0.134, nut smaller: 0.120. John thinks these are rolled threads.

Book Discussion

Introduction and Chapter 1

Discussion Leader: Simon

Intro Brief Summary: Hiding the works of machines that we use, decline in using tools makes us have a more passive relationship to material things. Will argue that working and fixing things with your hands is meaningful because it gives us agency. Not just the romantic aspect, but the utilitarian aspect. Agency is doing it for yourself, and confidence is knowing what you’re doing.

Intro Tech References: Some cars are designed to not have a dipstick, which reflects a lack of interest in working mechanically on your own car.

Ch1 Summary of Part 1: “Psychic satisfaction” Talks about experience as electrician starting young. Learned the value of doing things well, even if no one is going to see it.

Ch1 Summary of Part 2: In a period of time of the assembly line, the concept of manual labor started to shift to take independence and thinking out of it in exchange for efficiency. More effort back then to include vocational training in school. Makes distinction between craft and trade. Some type of manual jobs (plumber, carpenter) are more secure because it’s not efficient to have machines do them.

Discussion: Why have people started looking down upon blue-collar working (eg plumber)?   Because of the idea that education pushes society forward, and that plumbers aren’t going to push society forward as well. Also the idea that we don’t really realize that we need plumbers until our plumbing breaks. Are there really any jobs that can’t be replaced by automation and technology? Henry Ford dumbed down the trade of manufacturing. He increased inefficiency by increasing specialization. They have been moving back to increasing trade-based positions in companies like Barclays. In America we value intellectual stimulus in 4 year college, as opposed to a 2 year trade school. Another element of the book is to see the physical fruits of your work. The carpenter gets immediate feedback on whether his building is level. Problem solving versus problem finding: Psets are problem solving, whereas fixing a washing machine is diagnostically finding a problem. He says this is more high-level thinking.

Looking at 3-d modeling.

Computerized design, computerized engineering manufacturing. Safety factor of 2 means you’re in 2 degrees of failing. Thursday will bring in a 3d printer, to print out 3 axis mill.