2019-03-25 4 min read


Notes, 2019-03-25.
I don't do this often, but The Prepared recently crossed 5,000 subscribers - a number that feels like *something.* So, a big thank you to everyone who's supported it over the years, and a *big* thank you to our sponsors, business subscribers, and personal supporters for helping to sustain it.

The most clicked article in last week's issue (~19% of opens) was on the largest seamless stainless steel forging in the world.

Planning & Strategy.

  • A good explanation of an early iPhone dev board. If you're in the Bay Area, you can see a similar board at the Computer History Museum.
  • Gimlet Media's staff is unionizing; (some of) Kickstarter's staff wants to as Perry Chen leaves.
  • Mittelstand are Germanic small to medium sized businesses which "are characterized by a common set of values and management practices" like emotional attachment, long-term focus, lean hierarchies and strong regional ties.

Making & Manufacturing.

  • It came to my attention this week that Helicoils (generically, wire thread inserts) are not a universally known thing. I tried to find a good link about how Helicoils can be used to prevent galvanic corrosion between aluminum and stainless steel (which I believe is how I really became aware of their utility; I've also used them on damaged bicycle cranks) but alas, all I found was this *excellent* NASA paper titled "Fastener Design Manual." Oh well :)
  • Andrew (whose blog is a near-perfect encapsulation of "a series of interesting machinery projects, documented well") wrote in re: the laser rust removal link from 2019-03-11:

    The real benefit [of laser surface preparation] is that you have virtually no waste (just ablated material, generally small particles), and you can plug it into a 6-axis robot and go. [Powerlase Photonics, my client's] initial customers were in automotive, and they used it to depaint tailored blanks prior to welding. A big business that they and their competitors have been trying to break into is aircraft depainting, which is primarily done chemically right now...From the standpoint of energy use, there are a few factors in the overall system's efficiency:
  • Power supplies converting AC to DC for diodes
  • Diode efficiency (usually 30-40%)
  • Laser cavity conversion efficiency (usually 65-75%)
  • In the case of high power lasers (4 & 6kW are common now, 10kW are on the market and becoming more affordable) there is a beam combiner that brings multiple cavities together, and usually has losses of 5-10%.
  • Delivery system: usually ~5% losses, but highly dependent on application, can be as low as 1%.
  • Absorption at the target: wavelength dependent So, depending on the system, usually delivered power is 20-25% of wall plug power. So that 1kW laser is using 4-5kW of power.  

     IMO this is a *great* breakdown of laser surface prep's efficiency - if anyone out there can offer something similar about chemical rust conversion/surface prep I'd love to see it!
  • The NY Times on the American resurgence in cardboard manufacturing, replete with *excellent* photography and dripping with historical context.
  • More creative uses for FDM style printing, this time with floating filament structures. I'm also a huge fan of Neri Oxman's glass printing, which is even more impressive in person. Fun fact: Oxman recently married Bill Ackman, the polarizing activist investor who last year dropped his famous short position on Herbalife.
  • How Backblaze's storage pod is so cheap.

Maintenance, Repair & Operations.

Distribution & Logistics.

Inspection, Testing & Analysis.

  • Plastic shopping bag bans result in increased sales of plastic garbage bags. "Using sales data from retail outlets, I found that bag bans in California reduced plastic carryout bag usage by 40 million pounds per year, but that this reduction was offset by a 12 million pound annual increase in trash bag sales. This meant that 30 percent of the plastic eliminated by the ban was coming back in the form of trash bags, which are thicker than typical plastic carryout bags."
  • A very good twitter thread analyzing the chain of problems (in engineering, economics, and operations) that resulted in the Lion and Ethiopian Air crashes.
  • If anyone has experience with the Baidu Maps API (or any geocoding API with good support in PRC) send me a note.
  • "A huge fireball exploded in the Earth's atmosphere in December, according to NASA."
  • Virginia is not impressed with Elon Musk's tunnel-building: "I don’t mean to suggest that they don’t have a serious plan in mind, but I don’t consider the steps they’ve taken to date to be substantive. They’ve purchased a used boring machine. They’ve put a bore in the neighborhood where they developed the SpaceX product, and they’ve taken a Model 3 and put guidewheels on it and they’re running it through the tunnel at 60 miles per hour...None of that, I think, is really significant from a standpoint of moving this process forward."


A short, well-produced, and iconic history of Hasselblad cameras in space.

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