Also, Galileo visited the arsenale and was fascinated by the many interesting questions of mechanics raised. For instance, why do the oars in the center of the ship most account for the ships movement? Galileo experimented with new oar designs as well as questions of naval architecture and artillery design, eventually moving to Venice and working as a consultant for the Arsenale. It was the world's first mass munitions factory.
Some links for further reading:
Edit: Also responsible for a vast supply of historical datasets.
Edit 2: IMHO, the most fascinating is all the tie-ins between artillery, spycraft, astronomy, aerospace/rockets, geodosy & cartography (and invention of the chronograph), tidal monitoring & weather keeping, nuclear weapons, gps, and probably a dozen more topics I'm forgetting off the top of my head.
Individually, each of these is a mammoth of a topic on its own. But the interplay in their development (as influenced by big-picture military strategy) is just mind-boggling to me. It is by far, the most interesting, persistent, and deep rabbit-hole I've encountered.
(Hint: Ballistic missiles are essentially long range artillery. Hint 2: They require gravitational variation to be taken into account for targeting.)
> By January 1801, Whitney had failed to produce a single one of the promised weapons, and was called to Washington to justify his use of Treasury funds before a group that included outgoing president John Adams and Jefferson, now the president-elect. As the story goes, Whitney put on a display for the group, assembling muskets before their eyes by choosing (seemingly at random) from a supply of parts he brought with him. The performance earned Whitney widespread renown and renewed federal support. It was later proven, however, that Whitney’s demonstration was a fake, and that he had marked the parts beforehand and they were not exactly interchangeable. Still, Whitney received credit for what Jefferson claimed was the dawn of the machine age.
I wonder how original Colt 1911 were produced for military orders? I can’t see hand fitting those.
The AR-15 is fully interchangeable, but I have read of takedown pins on Colts not fitting more modern lowers receivers. Also wonder if the gas system has to be tweaked? The FN-FAL has an adjustable gas block, but that may be due more for ammo than parts compatiblity.
Edit: adjustable gas systems are in fact there to tune for ammo variations and fouling.
More likely it means someone cycled the thing to make sure it worked before slapping their "qa by <unintelligible scribble>" sticker on the product or packaging
It's mostly just marketing mumbo jumbo to make it seem like a fancy hand crafted product. Back in "the day" the marketing people would have advertised that things were made by precision machines. Today labor is expensive and machines are cheap so they're advertising that they put a lot of labor into it in part to justify the price (and the reverse would have been true in the early 1900s, they'd emphasize the machine contribution).
Firearms are tight like a retired hooker compared to the kind of tolerances any reasonably modern manufacturing operation of that sort (mostly machining and stamping/forming) is capable of working in (they need to be loose so all those steel on steel parts will move like they're supposed to). Loose fitment tolerances translate to less need for super precise parts to begin with. Say you have a slide that wants .010"+.002"/-0001" of clearance. Sure you can make that part to .0005 but insisting on that level of consistency just adds unnecessary cost to do so when you have an entire .0003" space to shoot for.
For ultra high precision stuff tighter tolerances and more consistency are used but that's mostly limited to the pressure bearing parts of the action that touch the case/bullet (the goal is to get that cartridge to fit in there the same way each and every time).
Some of the most reliable firearms out there use very loose tolerances. For a 1911 I feel very safe saying that the modern high end ones do it more because they can than because it improves performance in any measurable way. High end guns almost by definition will never see enough use to get to the point where manufacturing it more precisely could ever effect reliability.
Put another way, the manufacturing process had built-in methods for self-correcting systematic error. They just weren't guaranteed to be consistent in the long term. (I'm sure there's got to be a more technical description for this, but it's beyond my knowledge).
I know semi-modern (opto-mechanical) survey equipment is manufactured on similar principles of self-correcting deviation (although these also tend to be dependent on strict method of operation for it to work itself out).
It wouldn't be a stretch to think a firearm as old as the 1911 was manufactured in a similar fashion as some point. Especially if there was a way to keep the long term deviation centered within spec. But that's just my guess.
Seems like a really simple concept, just like the drill press for that matter, but it took so long for people to realise the potential.
These guys were fast, but nowhere remotely as fast as thread-rolling machinery of course.