logical

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It's easy to talk about converting over but I imagine the great majority of those calling for absolute conversion towards metric is completely ignorant about the immense scale of imperial hardware (fasteners nuts and bolts) used globally because of aerospace. It's easy to change the numbers on a piece of paper. It's not so easy to respec a commercial/military aircraft from inch to metric. Not only is the final component changed but almost every legacy tooling that has existed to manufacturer and assemble such goods. And trust me the world isn't all CNC machining as you might think it is.
I'd like to phase out of inches eventually but somethings are prohibitively expensive to convert without starting fresh from the ground up. Hard to justify such a "backwards" step to shareholders.
Tl;Dr inches is here to stay whether you like it or not.
- Other. Countries. Did. It..
  Besides all the Imperial standards are calibratrated from metric since the US imposed the standard during WW2.
  
  Except well... when it comes to aerospace hardware. It's all inch threads. There are no metric hardware (bolts and nuts) in planes. They (countries other than the US) literally have to have inch hardware and tools to service aircraft.
  While the base inch unit is derived from metric. Actual industry standards like https://www.sae.org/standards/content/as8879/ are not 'metric' by any means.
  
  Again, all standards ( gauge blocks and the like) are all calibrated from a metric standard.
  This is due to how Carl Evard Johansson made them.
  You might be using the SAE standard, but that is referenced to the SI standard which is what metric became.
  
  You're confusing Metrology Calibrations/Traceability with standards for industry quality.
  And just because the inch unit is derived from a SI unit it doesn't mean an M12x1.25 bolt will be a functional replacement in a 1/2-20 thread.
  There's more to the inch/metric debate than your focus on academia...
- Hard to justify such a "backwards" step to shareholders.
  Aaaaand there it is, the usual boat anchor encased in concrete with two society-sized boot holes molded in.
  
  why fix what aint broke? Aerospace bolts and nuts are orders of magnitudes more regulation stringent than automobiles. And it really isn't just as simple as changing bolts and nuts... Basically the entire plane has to be created again. Every single blueprint with a new hole/countersink needs to be updated. Every subcontractor and emergency repair facility needs to have their legacy mylar drawings updated.
  All for what? Getting off inch system because it's "illogical" for a select group?
  And unfortunately, doing work costs money.
  If there's a story I want to hear, is one of how automobile companies transitioned into Metric. I'd imagine it's not too difficult since they come up with a new vehicle platform every couple years.

465 comments