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A comment on FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes. Parent comment

Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by bamboozled on Friday July 24, 2020 @10:36AM (#23940017)
I love that out of all the more complex ideas about what may have been used, it turns out likely to be a solid piece of metal with of a given thickness, couldn't get more simple than that.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by WrtCdEvrydy on Friday July 24, 2020 @11:15AM (#23940466)
If you're into 3D Printing, feeler gauges are also a great way to level your bed... move the extruder 0.04 above the bed at four points, stick your 0.04 feeler under it and adjust the springs until it touches the feeler. Voila, one perfectly leveled 3D printer bed.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by serf on Friday July 24, 2020 @01:43PM (#23942353)
that's a weird in-between two more popular ways of doing it.

The non-precise way you've already heard about, sheet of paper, check for dragging.

The better (more precise) way, is using a magnetic base micrometer attached to your extruder head. You can then watch the bed run-out in real time; if your 3d printer supports many configurable sections across the bed ( I know Prusa style cartesian units mostly all support quadrants) you can record the run out everywhere across the plane without any more physical work than watching the gauge and recording the results.

P.S. be careful using both the micrometer and the feeler gauges on a 3d printer bed. Most work plates now-a-days are using PEI coatings that'll scrape off easily with metal-on-metal contact.

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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by WrtCdEvrydy on Friday July 24, 2020 @02:05PM (#23942636)
> using PEI coatings that'll scrape off easily with metal-on-metal contact.

Yeah, you're correct, it's a glass bed so I use it to do the 4 corners (every few months) and then use a BL touch to do a 3x3 grid on top of it.

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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by jrockway on Friday July 24, 2020 @11:54AM (#23940981)
Most people use a sheet of paper for this. I wouldn't use it to check the tolerances of an airplane part, but it gets you 99% of the way there.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by WrtCdEvrydy on Friday July 24, 2020 @12:40PM (#23941555)
I like the sheet of paper method, but I have gotten a lot more use out of a $0.15 feeler gauge and I get consistently better prints... but I don't have the tools to scientifically quantify it so it could be placebo.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by cartoonfoxes on Friday July 24, 2020 @12:32PM (#23941466)
They're deceptively simple. If you want to get into the history of modern manufacturing, a lot can be written about the development of gauges of accurately known dimensions.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by nitrogen on Friday July 24, 2020 @12:40PM (#23941566)
I went down a rabbit hole of videos last yearish about the origins of precision (that should be a searchable phrase to get started).
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by cartoonfoxes on Friday July 24, 2020 @12:45PM (#23941626)
Go find a PDF of "Fundamentals of Mechanical Accuracy" by Wayne R. Moore, if you haven't already seen it. That book, along with George Daniels text "Watchmaking" are some of the top inspiring works on the mechanical arts in my collection.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by noir_lord on Friday July 24, 2020 @06:31PM (#23945156)
Somewhat sadly a lot of the drive for that tolerance was weapons, until we could accurately make very high tolerance (for the day) parts you couldn't use parts from one rifle on another without a smith, it certainly wasn't field serviceable - this imposed a lot of maintenance overhead until they solved it properly.

It seems like we really like to push the limits when it comes to shooting each other.

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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by linuxftw on Friday July 24, 2020 @07:20PM (#23945487)
> Somewhat sadly

Weapons can be used for defensive purposes. There's nothing inherently wrong with them, only how people use them.

> parts you couldn't use parts from one rifle on another without a smith

You cannot swap bolts in the field on most rifles. At minimum, you require a go/no go gauge. The tolerances on modern firearms are very precise.

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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by int_19h on Friday July 24, 2020 @09:48PM (#23946238)
That the tolerances are so precise is exactly why you can do that on most modern rifles. It depends on the design - specifically, how they achieve headspace. On an AR-15, or almost any firearm with a similar bolt locking arrangement, bolts - indeed, entire BCGs - are swappable in practice, and people do that routinely without bothering with gauges regardless of what the manual says. On AK and similar designs, yeah, that's a really bad idea.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by bilbo0s on Friday July 24, 2020 @11:17AM (#23940491)
couldn't get more simple than that.

Believe it or not, that's actually a lot of the idea that drives commercial aviation design.

Or used to anyway.

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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by KMag on Friday July 24, 2020 @11:23AM (#23940574)
... and most engineering in general. Simple solutions tend to be very robust and often cost-effective.
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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by noir_lord on Friday July 24, 2020 @06:31PM (#23945161)
and easier to troubleshoot/replace.

> A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over, beginning with a working simple system. - John Gall

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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by na85 on Friday July 24, 2020 @11:39AM (#23940785)
That's what real engineering is about: the simplest tool or process that will get the job done.

Despite what we see on the web more and more, this principle applies to code too.

It shouldn't be about stacking up layers of complexity for no good reason.

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Re:FAA issues emergency directive on 2,000 Boeing 737 NG, Cl... by Gibbon1 on Friday July 24, 2020 @03:03PM (#23943287)
Somehow your comment reminds me of a pissing match I saw between a young aerospace engineer and an old retired one. The old guy was right in his argument that it doesn't matter what the constraints on materials and dimensions are, it that they come from somewhere and are documented.

His example was designing brackets for a Indonesian construction company that was using locally sourced tropical softwoods for constructing buildings. The brackets were designed to be made with 'steel' and the tolerances were compatible with a hungover guy running a drill press.

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