Cornhole Board Update

An update on the progress of my “cradle to cradle” sustainable aluminum cornhole board construction:

I talked with the people a The Crucible in Oakland and despite being a member and having experience with the machines I want to use, they won’t let me access the machine shop as part of their “create” program without taking a bunch of machine shop classes there first. Taking the machine shop classes and joining the “crate”program for 90 days would add $930 and 4 months to the cornhole board project. Considering I could buy a brand new drill press and band saw (the only two machine shop tools I need to build the board) for less than $930, and have this thing built in a week, that’s a terrible deal.

So I’m going to send out a “request for quotes” to various machine shops in Oakland and Berkeley to see who will manufacture my parts for the least amount of money.

The shops I’m going to send RFQs to are:

Estimating the machine setup and manufacturing time for each part, I’m worried that this could get pretty expensive:

  • Upper and lower bars:  2 angle cuts (10 minutes each), 11 large straight holes (2 minutes each), 3 small straight holes (2 minutes each), 4 small angled holes (5 minutes each), 4 angled recess holes (5 minutes each): 2*(2*10+11*2+3*2+4*5+4*5)=176 minutes
  • Side bars: 2 angle cuts (10 minutes each), 11 large straight holes (2 minutes each), 4 small straight holes (2 minutes each), 4 small angled holes (5 minutes each), 4 angled recess holes (5 minutes each): 2*(2*10+11*2+4*2+4*5+4*5)=180 minutes
  • Cross bars: cut to length (5 minutes ), 14 large straight holes (2 minutes each), 4 small straight holes (2 minutes each): 2*(5+14*2+4*2)=82 minutes
  • Legs: 1 angle cut (5 minutes), 1 small straight hole (2 minutes), 4 large straight holes (2 minutes each): 2*(5+2+4*2)=30 minutes
  • Total manufacturing time: 7.8 hours

Even at California minimum wage ($8/hour), the board would cost $62.4 in labor. At a more realistic $50/hour, manufacturing would be $390.

So as a test of our globalized manufacturing system, I’m also going to upload the RFQ to MFG.com to see how much it would cost to get it manufactured in a Malaysian sweat shop (which would completely go against the entire sustainability ethos of the project).

 

Cornhole4

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Psychological Trigger Points For Crude Oil Demand Destruction

I’ve talked about demand destruction before in this blog. Demand destruction occurs when the marginal benefit of using more crude oil exceeds the marginal cost for people. Essentially, when oil prices go too high, people use less oil. On a personal level, this means that people may drive fewer miles by staying closer to home on the weekends, they might postpone a long-distance vacation, or they might start taking the bus or work from home instead of commuting by car. The Economist wrote a nice article on this phenomenon last year where they stated “in the rich world oil demand has already peaked: it has fallen since 2005.”

While demand destruction occurs across every price up the ladder, there are certain psychological trigger points where people “wake up” to the fact that oil has gotten very expensive. Gas stations post their prices on the street and people notice when prices pass certain thresholds. In the United States, we price our fuel in dollars per gallon, and people definitely notice when regular gasoline passes $4 per gallon. In fact, when we look at the average US street price of regular gasoline, we see it bounces off a ceiling of $4 per gallon:

When Americans see $4 a gallon on their neighborhood gas station’s sign, the price of oil immediately becomes front-of-mind and they start changing their behavior. Already, there are signs that motorization in the US has peaked. We can imagine that if gasoline prices rose past $5 per gallon, people would dramatically cut back on their gasoline consumption.

In Europe, gasoline is priced in Euros per Liter. The EIA keeps a summary of current prices in Europe here. In Germany, the largest economy in Europe, 48% of cars are diesel, so the price of diesel is more important than the price of gasoline. Looking at historic diesel prices in Germany we also see a ceiling, but it is at €1.5/liter:

We can imagine that the next threshold in Germany is €2/liter, at which point Germans would almost certainly cut back significantly on their fuel consumption.

In China, gasoline and diesel is priced in yuan/liter. Current prices are ¥1.77/liter for diesel in Beijing. In Chinese culture, many numbers have strong physiological associations. Seven a lucky number associated with “togetherness” – so today’s price of ¥1.77/liter might be welcomed by people. Four is considered an unlucky number. In fact, many buildings in china don’t have a 4th floor (similar to how many buildings in the west don’t have a 13th floor). So while ¥2/liter is likely the next physiological threshold in China, we can imagine that if prices rose to ¥2.44/liter, they would be front-of-mind for people.

Converting Crude Oil Prices to Gasoline Prices
We can convert the price of crude oil to the price of gasoline by looking at the historical difference between these two prices. There are 42 gallons in a crude oil barrel, so a $100 crude oil price is $2.38 per gallon of crude oil. Obviously crude oil is the largest input cost for gasoline, but when you buy a gallon of gasoline you’re also paying for taxes, marketing, distribution and refining costs. The EIA has created a nice graphic showing what you pay for in a gallon of gasoline:

Over time, the price of crude oil has become a larger percent of the overall cost of gasoline:

Today crude oil accounts for about 75% of the cost of gasoline in the United States and for about 35% of the cost of diesel in Germany (where taxes are far higher). Using historical data we can come up with a few simple rules of thumb for converting crude oil prices to local gasoline prices for the US, Europe and China:

  • United States: Crude Oil ($/bbl) / 31.5 = Gasoline Price ($/gallon)
  • Europe: Crude Oil ($/bbl) / 80 = Diesel Price (€/liter)
  • China: Crude Oil ($/bbl) / 61.5 = (¥/liter)
For the record, there are more accurate ways of doing this – like calculating the refinery yield for each product and adding on top of that the taxes and distribution cost for each region – but for this blog post some rules of thumb will suffice.

Demand Destruction Thresholds
Going back to our psychological demand destruction thresholds, we can use our rules of thumb to convert them to crude oil prices:

  • €1.5/liter in Europe: $120
  • ¥2/liter in China: $123
  • $4/gallon in the US: $126
  • ¥2.44/liter in China: $150
  • $5/gallon in the US: $157
  • €2/liter in Europe: $160
So looking at future prices, if crude oil hits $120-$125 per barrel, we will likely see demand destruction as certain psychological triggers are hit around the world. The next threshold appears to be $150-$160 per barrel, at which point demand destruction could be quite severe.
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Pneumatic Ram Drag Racing Car Accelerator

I’ve often wondered why drag race cars don’t use pneumatic rams to give them a boost of initial acceleration. The system would work on the same principles as an aircraft catapult. You could set up the ram to push against a rubber pad that you set on the ground, pushing you forward. Or you could set up a block on the ground, similar to starting blocks that Olympic runners push against at the start.

starting-blocks

The pneumatic ram could be supplied by a scuba tank (also called a diving cylinder). A scuba tank holds 12 liters air at 3000 psi. That’s over a million joules (1 megajoule) of energy! For comparison, a gallon of gasoline contains 120 megajoules of energy, so releasing the air of a diving cylinder is equivalent to burning 1 fluid ounce of gasoline. The difference, however, is the scuba tank can release all of its energy at once, while the gasoline would have to be burned by an engine. When a Bugatti Veyron’s 1,001 horsepower engine is running full-out it uses 1.4 gallons of gasoline per minute. That’s 3 ounces of gasoline per second or 1 ounce every 1/3 of a second. A diving cylendar could certainly release all of it’s energy in 1/3 of a second, matching the Bugatti Veyron’s massive engine horsepower with far less weight.

A 3000 psi diving cylinder may be able to deliver 20,000 kilopascals of pressure to a pneumatic ram. You could take all of that pressure and put it into a pneumatic ram. An air cylinder with a 80mm bore diameter would deliver about 100,000 newtons of force. That same 80mm bore pneumatic ram has a stroke of 300mm. So how fast would a 1000 kg car be traveling from this one ram pushing on it from a dead stop?

To find acceleration when we know mass and force we can use Newton’s second law of motion:

  • m = mass = 1,000 kg
  • F = force = 100,000 N
  • Newton’s second law of motion is F = m*a
  • ∴ a = F/m = 100,000/1,000 = 100 m/s^2

For comparison, a Bugatti Veyron Supersport can acclerate from 0-60 MPH in 2.46 seconds. Since 1 MPH = 0.44704 meters per second, the Bugatti acclerates to 26.8224 m/s. Since Acceleration = change in speed ÷ time interval, the acceleration of the Bugatti is 26.8224/2.46 = 10.9 m/s^2.

To find the final velocity (instantaneous velocity) when we know distance and acceleration we can use Torricelli’s equation:

  • Torricelli’s equation: Vf^2 = Vi^2 + 2aΔd
  • ∴ Vf = sqrt(Vi^2 + 2aΔd)
  • vf = final velocity (what we want to know)
  • vi = initial velocity = 0
  • d = distance = 0.3 meters (the stroke of the ram)
  • a = acceleration = 100 m/s^2
  • Vf = sqrt(Vi^2 + 2aΔd)
  • Vf = sqrt(2*100*0.3) = 7.75 meters per second
  • 1 meter per second = 2.23694 miles per hour
  • Vf = sqrt(2*100*0.3)*2.23694 = 17.3 MPH

So a pneumatic ram could a accelerate a 1,000 kg car to 17 MPH over a distance of just 1 foot!

What if we used 10 rams? Would we be going 170 MPH?

  • Ten 100,000 newton rams  = 1,000,000 newtons (1 meganewton!)
  • a = F/m = 1,000,000/1,000 = 1,000 m/s^2
  • Vf = sqrt(2*1000*0.3)*2.23694 = 54.8 MPH

So if you used pneumatic power to create 1 meganewton of force, you could accelerate a 1,000 kg car to almost 60 MPH in just 1 foot!

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Solidworks Progress

I’ve made a bit of progress on the solidworks model of my three-wheeled electric car. I’ve been playing around with solidworks for my aluminum cornhole board and it’s amazing how quickly you can design and assemble parts once you get the hang of it. The key is making parts “fully defined” and getting the mates right. I’m a huge fan of GrabCAD and McMaster-Carr for solidworks models of parts.

Here’s how it stands:

Solidworks_Build-01

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Questions

“It’s hard to make predictions, especially about the future.”

Peak Oil

  • What oil price can the global economy support without going into a recession?
  • Have we passed peak $50/bbl oil?
  • Have we passed peak $100/bbl oil?
  • With oil companies cutting back on capital spending, how will global oil production rates continue to increase?
  • Has global conventional oil production peaked?
  • Will increases in unconventional oil production be able to offset declines in conventional oil production?
  • What percentage of oil and gas well casings fail over a 1000 year time span?
  • How many earthquakes are the direct result of hydraulic fracturing and the resulting underground waste water disposal?
  • Do we have enough water to continue increasing the rate of shale oil and gas extraction?
  • Will we see peak oil because of peak demand or peak supply?
  • Once we pass peak oil, will we have a smooth transition to sustainable energy sources or will we have a collapse?
Climate Change
  • Once you account for the methane that leaks into the atmoaphere along the life cycle, is fracking for gas better or worse than coal for climate change?
  • What is a “safe” amount of global warming?
  • After all of the positive and negative feedback loops are accounted for, what is the real warming potential of a ton of greenhouse gas?
  • Given that warming potential, how many tons of greenhouse gas can we safely emit into the atmosphere?
  • How much economically-extractable hydrocarbon energy is left in the ground?
  • Is the amount of economically-extractable hydrocarbons in the ground higher or lower than the amount we can safely emit?
  • Is it possible with current technology to hold global warming to a safe level without harming our economy?
  • When will we see a global carbon tax?
  • Will China unilaterally tax carbon?
  • Will politicians fail to act on climate change until we see catastrophic climate disruptions (thermohaline shutdown, megastorms, megadraughts, greenland ice sheet collapse)?
  • If politicians wait until a crisis to act, will it be too late to halt climate change?
  • If we fail to act, is it possible to reverse climate change through geoengineering?

Economic Sustainability

  • Is it possible in this century to provide 10 billion people a developed-world standard of living without destroying the environment?
  • Throughout history, when governments have rapidly debased their currencies through money printing, it has always led to high inflation. This time though, all of the government are doing it at the same time and we haven’t seen much inflation yet – is this time different?
  • How long can real interest rates remain negative?
  • What ever happened to breaking up banks that were too big to fail?
  • Why did the Federal Reserve Bank of New York say it would take 7 years to repatriate 674 tons of gold to Germany when they claim to have 6,700 tons of gold in their New York vault?
  • Can income inequality continue to get more severe every year without a triggering some kind of backlash?
“Plan for the future because that’s where you are going to spend the rest of your life.” -Mark Twain
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Cards Against Humanity Custom Camping Set

Cards against humanity is one of the best party games around – and one of the best games to play with friends when you’re out in the wilderness.

However, there are numerous problems if you want to take these cards on a backpacking trip:

  1. The cards are heavy – if you carry all 854 cards with you (from all the expansion packs) it would weigh over 1.5 kilograms (3.3 lbs)! (assuming each card weighs 1.8 grams)
  2. The cards aren’t waterproof – when you’re out in nature, things get wet and dirty
  3. The selection is limited – 854 cards sounds like a lot, but once you’ve played the game a few times, it quickly starts repeating itself

So I decided to use my excel wizardry to come up with a solution and create a set of mini waterproof cards against humanity cards.

I added in all of the original cards, all of the expansion pack cards, all of the cards from the Board Game Geeks forum as well as some of my own ideas to increase the number of cards from 854 to 1643.

The final result can be put in a ziplock bag and takes up significantly less room than the original cards while also being waterproof:

cards-against-humanity-custom-camping-set

For anyone who wants to create their own set, here are the directions:

Step 1: Buy some waterproof paper

Step 2: Download my excel spreadsheet: cards-against-humanity-custom-camping-set.xlsx

Step 3: Find a laser printer – not an inkjet printer (inkjet won’t be waterproof)

Step 4: Print out each tab of the excel workbook (except for the first two tabs) double-sided on the waterproof paper

Step 5: Cut your cards out

Step 6: ???

Step 7: Profit

 

Just like the original CAH, I’m releasing this workbook under the Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic (CC BY-NC-SA 2.0) license.

Tilting Three Wheeled Electric Car

I’m a big fan of electric cars.  Electric motors have some major advantages over internal combustion engines:

  1. 100% torque from 0 RPM – immediate power off the line
  2. Linear torque delivery – no “lumpy” torque delivery like turbo engines or diesel engines
  3. Lower complexity – an electric motor basically has 1 moving part while IC engines have hundreds
  4. Sustainable – oil is a finite resource and burning it causes all kinds of externalities. Electric cars are far more efficient and can be powered from renewable energy, making them far more sustainable.

The problem is that most electric cars today are either too heavy and slow (Nissan Leaf) or too big and expensive (Teslas).

I would like to have a small, nimble electric car that can corner corner and accelerate well. Electric motorcycles, like those from Zero and Brammo, are close, but motorcycles in general can never approach the cornering ability of cars. So my goal is to design and build an electric car that is small, lightweight and fast.

As an undergrad I was president of our FSAE formula racing team. I got to help out with some of the manufacturing of our car and race it in competition. We had an amazing team of super talented engineers that I learned a lot from.

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As an undergrad I also managed to build a dune buggy in my spare time:

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When I moved to Houston for my first job I bought another dune buggy and did a lot of restoration work on it:

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Through these  projects I’ve developed a design philosophy that is guiding me during this electric car project.

I’ve been following Dennis Palatov over at dpcars.net for a number of years now as he’s designed an built a few cars. I’ve really enjoyed how he has put his full design process out in the open for everyone to learn from and I’m hoping to do the same. It took Dennis 4 years from first sketch in May 2002 to first drive in September 2006 – so I’m mentally prepared that my project could take just as long.

I’ve also been following the story of Local Motors and love their revolutionary approach to crowdsourcing the design of the cars and having the owners build the cars themselves at local “micro factories.” In 2011 I flew down to Chandler, Arizona to meet the team and understand the business better.

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I truly believe that this type of business structure – crowdsourced design and micromanufacturing – is not only the future of carmaking but the future of manufacturing.  Once this project is further along, I’m hoping that this business model will allow everyone who wants one of my cars to have one.

So follow me along on the design journey…

Reference Library

How do you learn how to design and build a car from scratch? You have to become an autodidact and learn everything you can about the subject. I’ve personally been amassing a design library to help me along with this project. In order to speed up the process I’ve scanned and OCRed these references into searchable PDFs and put them into Evernote.  As I have read them, I have highlighted important points in them. This way, I am able to easily search for topics like “camber” or “kingpin inclination” and find all of the important passages on a particular topic across multiple sources.

There are a number of different sources you can turn to for learning about any subject:

  • Published literature – books, magazines, journals
  • Internet – forums, blogs
  • Courses – MOOCs can be great sources of information
  • Experts – nothing beats talking with experienced experts. They’ve already made all of the mistakes, so you don’t have to.
  • Customers – talking with customers about what they want in a car is perhaps the most important aspect of designing a car. Right now the customer is me (I’m building it for myself), but as this project grows I’m going to go out and talk to more enthusiasts.

Overall Design

Sustainable Design

Tire Selection

Suspension Design

Electrical System Design

Chassis Design

Body Design

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Wiring

Two of the main design goals of the car are simplicity and lightness. Wiring harnesses can become extremely complex and because they are made of dense metals like copper, they can also become extremely heavy. The wiring harness for the average passenger car now weighs 150 kg! That’s the weight of two passengers!

The guys at RB Racing have had to deal with extreme corrosion while racing their motorcycles on the Bonneville salt flats and have written a very nice tutorial on building corrosion-resistant wiring harnesses. Some advice from these seasoned racers:

  • Use Mil-Spec connectors
  • Use circuit breakers instead of fuses
  • Use heat shrink tubing on all connections
  • Use epoxy sealant on all connections before you shrink wrap them
  • Use Mil-Spec wire (MIL-W-22759/44)
  • Use Mil-Spec twisted pair wire ( M22759/16) for all sensor wires
  • Use K4 Triple Sealed Switches
  • Use thermal wire strippers so you don’t nick the wires
  • Use Daniels crimping tools
  • Use a Daniels Contact Retention Test tool to make sure all crimps will hold
  • Use Mil-Spec (Mil-T-43435B) Lacing Cord to tie wire bundles together
  • Use a Portable Shrink Tube Thermal Printer to print out labeled shrink-wrapped labels on each wire
  • Spray Boeshield T-9 on any metal surfaces that will be exposed to corrosion

 

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Tilting System

Camber Thrust

Tilting the wheels of a car so that they lean into a corner (like on a motorcycle) is most beneficial because it creates “camber thrust.” Tires can develop cornering force in two ways: slip angle and camber thrust. Slip angle cornering force is developed by turning the wheel in the desired direction of travel. When the wheel is turned the rubber on the car’s contact patch with the road deforms. This deformed patch of moving rubber creates a lateral force on the tire, causing the car to turn. Camber thrust, on the other hand, is generated when a rounded-profile tire is tilted into the desired direction of travel. The rounded edge of the tire causes the tilted wheel to want to follow an elliptical path, creating lateral force which causing the car to turn.

Because slip angle cornering thrust is developed from the deformation of the tire rubber, it generates a lot of heat. This heat degrades the tire over time. Camber thrust, on the other hand, does not deform the tire as much as slip angle thrust and thus does not create as much tire-degrading heat.

 

Tilting Approach 1: Lean Entire Vehicle with Driver’s Weight

The easiest way to create a tilting vehicle is to soften up the suspension and allow the driver to lean the vehicle by shifting his weight.

This method is used by the following vehicles:

Obviously the downside to this method is that the softer suspension required to allow the driver to lean the vehicle can cause the vehicle to have worse road-holding capability.

 

Tilting Approach 2: Lean Only the Suspension with Power Assist

The third method for tilting a car is to lean the suspension by itself with a power assist while leaving the car un-leaned. A system called the “Sacli Suspension” allows this to happen by creating two separate suspension systems that are linked in series. The “inboard” suspension controls up-and-down motion while the “outboard” suspension controls roll.

The first downside of this method is that it results in a much more complex suspension geometry, making it extremely difficult design and optimize.

The second downside of this method is that the driver doesn’t tilt with the car, so there is no sensation of leaning into the corner. Simply put, it isn’t as fun.

 

Tilting Approach 3: Lean Entire Vehicle with Power Assist

The second method is to tilt the entire vehicle using a power assist like a hydraulic ram or electric linear actuator.

This method is used by the following vehicles:

This is the method I plan to use for my car. There is no need to re-invent the wheel (literally) so I’m going to base my design heavily on the cars mentioned above.

Here is a CAD build-up of the Aprilia Magnet showing the suspension geometry – pause it at 11 seconds:

Here is a cardboard model of a similar suspension geometry created by Nathaniel Salzman:

 

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