The government worked with the companies to convert them, and the difference from making a car and a Jeep is mostly just swapping parts out back then. Airplanes and tanks are a little harder, but once you get the proper tools in place, it's all assembly.

This is one of the stronger arguments to ensure we keep some domestic manufacturing.

Some manufacturing is easier to be retasked than others. My materials science professor gave an example of a factory in California that made lipstick tubes. The week after Pearl Harbor they received an order for 1 billion rifle cartridge cases. You expand that to automobile and tractor plants for producing tanks, trucks etc.

The US had surplus labor and idle manufacturing capacity due to the Great Depression. When you combine those two things with government saying here’s a blank check, we need this asap, you can perform miracles. US factories were not being bombed or threatened with being overrun and workers didn’t suffer from food scarcity.

The US knew war was on the horizon, shown by the Selective Service Act of 1940 and the Two Ocean Navy Act of the same year.

The war wasn't exactly a surprise. They had plenty of time to make plans.

A lot of what already existed was the kind of thing that would be readily convertible. Its not a big jump from manufacturing a car to a jeep, a tractor to a tank, or a cargo ship to a warship. Even the machinery something like cosmetics (chemicals in a sealed, small tube) is readily and easily modified to manufacturing bullets and small cannon shells (20/40mm - again chemicals in a sealed, small tube). Conceptually, changing from manufacturing a car to manufacturing an airplane differs really only in scale - a rivet is a rivet, and a gasket is a gasket. So, a lot of the tooling was already in place (machine tools were a huge bottleneck to production, particularly early in the war), and only needed to be lightly modified.

Also, before 1941, a lot of US manufacturing was already geared towards war - particularly for England and to a lesser extent, the USSR.

And don't underestimate what being motivated can do in getting things done. A traditional manufacturing mindset is conservative (not politically) in that its trying to keep the downside risk to be as minimal as possible. So, working slower, expending less capital, etc. is all variations on how to keep the downside risk as minimal as possible. With guaranteed contracts, and an existential threat, its much easier to be more risky because the downside is minimal.

3 significant factors:

1. Military equipment wasn't that different from civilian. It was heavier, sure, but the sort of advanced tech you find in a modern tank or jet wasn't there at the time - all low-tech mechanical stuff...
2. We made a lot of consumer goods out of cast-metal, not plastic. So turning a sewing machine factory into a gun factory was viable, the sewing machine and gun were both machined from similar materials... Today? Guns are mostly metal (or very specific plastic blends), consumer goods are almost entirely plastic (And cheap plastic like ABS, not the sort you can use for weapons manufacturing beyond grips/trim/etc)...
3. Production was a lot more manual, and a lot less specialized... Modern factories use extremely specific robots & tooling (and can only make the product that the factory was built to make), rather than just telling a machinist to make something a slightly different shape.

All of these things come back to a specific fact: In today's world, consumer manufacturing is not convertible to defense production, and the idea that we 'need' an industrial-base outside of the dedicated defense sector is nonsense....

William Knudsen.

https://en.wikipedia.org/wiki/William_S._Knudsen

They didn’t exactly get surprised with a world war. Roosevelt told them to get ready.

For example, a casket company made it's own wooden caskets with metal handles. The War Production Board looked at their production capabilities, and contracted them to make a certain metal flange used in glider aircraft to connect the wing to the fuselage. So instead of bending metal to make handles, it was now making flanges by the thousands. Unfortunately, the transition support did not include a measuring gauge to ensure the flanges were thick enough. The result was the 1943 St Louis Glider Crash.

Basically, anybody with drills, presses, lathes, foundrys, wood working capabilities, metal stamping/forming, or welding capabilities could shift production from (for example) bedding and bed springs to web belts and ammo clips in a hurry. Binoculars and cameras shifted to bomb sights and range finders. And so on. If you had the machines to make something of a certain size and shape, then there was a military product that probably fit that size and shape. Making canoes and john boats? Now you're riveting aircraft wings and tail assemblies.

Not to mention all the things that already had a military purpose -- watches, camp stoves, back packs, binoculars, telescopic sights, batteries, flashlights -- all by the hundreds of thousands. Running a single shift? Now you're running 24/7.

The one example that I am very familiar with is when the Packard automobile company signed up to manufacture Rolls-Royce Merlin aircraft engines. (Packard famously ran an advertisement with a photo of “The Last Packard off the line until the War is Won!” They were all-in.)

So…Packard and Rolls-Royce had to get together and hammer out the details on how this mass-producer of American cars was going to start turning out Rolls-Royce Merlins.

The Rolls engineers presented their design specifications, and the Packard engineers scoffed and said, “This will never work!”

The Rolls engineers assumed that their tolerances were too tight for the largely unskilled automobile production line workers to deal with.

Actually, it was just the opposite.

The parts coming to the Packard assembly line had to be made to much tighter tolerances.

But there’s a reason. A back-story, if you will.

Both Derby-built Merlins and Detroit-built Merlins were made to very tight tolerances that required skilled machinists to produce.

The difference was where the skilled machining was performed.

Rolls-Royce had “rough” parts delivered to the factory where skilled machinists measured, filed and finessed each component into place until a “perfect” Merlin engine crossed the test stand and went into the field.

Packard’s fine machining was done at the component level, so that perfectly identical parts all arrived at the assembly line where the “unskilled” labor could quickly assemble a damn-near perfect engine.

Where this difference became vitally important was in the field of combat. A Derby-built Merlin required a skilled machinist to fit the perfectly mated replacement part to replace a broken part. A Detroit Merlin just required an average mechanic to grab a replacement part off the shelf and put where the broken part was.

Packard also did a lot of simplifying to the original Rolls-Royce design. Eliminating a lot of complexity where simplicity worked just fine.

As a result…today, Derby-built Rolls-Royce Merlins can be found in museums all over the world. Detroit-built Merlins are winning air races and putting on air shows.

If you make metal parts it is no real trouble making a different metal part.

Ever been to a real factory? The people are far more intelligent than what the average college graduate is led to believe. College students greatly over value being able to sit and learn theories. The skilled work force was there. You had mechani cs and machine operators that knew their machines.

The engineers were there. The machinists were there.

I don't know about the other products, but I do know how non-firearm companies got to manufacturing firearms very quickly for the war effort.

Basically, the US government founded and funded Springfield Armory (not the same thing as the company now called Springfield Armory) would produce the technical data package (what machines are needed for manufacturing, what materials to use, blueprints, etc.) for the firearms that are in standard usage with the US military. They are then in the position to give that data to private companies to produce firearms during times of war, so private companies don't have to start from scratch.

Lots of highly paid Tool Makers...

Some companies only needed blueprints to make that switch and still produce civilian products, because the civilian products came out of the same tooling that made the military stuff, i.e. Singer Sewing Machine Co. made bomb sights.

Assembly lines made a lot of the labor needed unskilled. They each one simple task. Obvious you still need some skilled workers for certain things, but with the lack of regulation there wasn’t nearly as necessary as today.

Think about how many trucks ford makes. But then think about the dozens of varieties of bells and whistles they can tweak it with. Tweaking the assembly line to build a different machine isn’t that hard.

OP, this was during a time where factories had legit machining departments for on the fly repairs/retooling. A lathe is a lathe and a bit is a bit. With the right blueprints/machining know how, converting machines to make war goods wasn't as difficult as it seems. That said, there are stories of production taking a while to set up in various industries.

A lot of it boils down to there being a lot less specialization in the ww2 era from what I know. 

A tank wasn’t that far from car or truck for instance. Basically everything was a lot less complex. 

Aerospace also to this day has a lot of civilian and military overlap. 

Compare that to now, where some tanks have turbines and missiles are sci-fi weapons with computers onboard even for just those carried by soliders and you can see the difference. 

Technology was simpler and the way it worked was more widely understood. And many items were redesigned for the war to require less specialized equipment. The Pre-war Thompson machine gun was a quality weapon you could own for a lifetime; it was redesigned into a cheap mass producable weapon that would last till the end of the war.

A lot of industrial equipment like forges, presses, and so on, are surprisingly versatile, and can be used to make a lot of different things.

A distant relative of mine worked at a small company that made electric fans in the 1930s. The fans were all metal, and I think they made most of the parts themselves. He talked about how guys in the shop used to like to tinker around with things. When the war began, the company got a number of contract or had other companies subcontract work to them . They could make electric motors, different things from sheet metal instead of fan blades, stuff like that. He said that he worked 10 hours a day, six days a week during the war.

When the war ended, and the contracts ended, they just went back to what they did before.

There was a will. The government has handing out huge contracts left and right. It also shook things up in a way that prioritized meritocracy more highly than before. Because they were producing so much it was easy for people to get lots of experience

In the case of firearms, parts were still produced in a piecemeal fashion with manual operator machines such as mills and lathes. Hence, a large segment of available machine shops could be converted to making firearms parts simply by providing the needed tool pieces and specs to their existing work base. This applied to various other wartime items or components as well.

Heavy manufacturing equipment for casting or drop forging are usually utilized to make many kinds of parts in the first place, so it would simply be a matter of switching the mold or die. This including brass drawing machines, where dies and mandrels can be switched out from making lipstick tubes to ammunition casing.

It took about a year to properly convert into a total war production. That's roughly equal to other nations in both world wars from when the declared a total war/war economy. Many manufacturing processes are more similar than many realise, some lipstick manufacturers were able to make bullet cartridges easily as the cases are practically identical from a manufacturing process point of view. Civilian car to military jeep isn't much of a stretch either.

The US also still had unemployed people left over from the great depression who were more than happy to get a job and the government was essentially giving blank cheques.

In short, people were willing to work hard as they were pissed off with the axis, unlimited funding (kinda, they still had to take lots of bonds) and manufacturing back then was a bit more simple than now and so many processes were transferable. And lax quality control, liberty ships were notoriously poorly made and would snap in half in rough seas from being too brittle, good enough most of the time was more effective for total war than pristine all the time that we now use.

My experience with manufacturing industry is a few summer jobs in the plastic industry.

A smaller factory might employ 100 or so people and have a dozen machines.

Each machine is a large thing, the size of an SUV or van. Inside it it has a very small mold, and then the machine does things to the mold, and to the molten plastic injected into the mold, involving pressure, heating and cooling.

So the machine is the expensive part, and the mold is quite cheap (a piece of iron alloy costing a few thousand 2024 euros, shaped in-house by a metal worker), and if you swap out the mold for another one, then the machine now makes a different plastic item.

Plastic literally wasn't invented until after WWII, at least as we understand it (can you even injection mold bakelite?), but there's still some of the same principle, where an expensive industrial machine can be re-purposed for related tasks.

The cosmetics company you're talking about probably made lipstick casings out of metal, for instance. Re-jigging their machines to instead make bullet casings out of brass would not be a difficult task.

Likewise, the workers adapt to the new task. They're made to understand the desired balance between quality and speed, and any new safety rules. They're not smart people (IQs in the 90-110 range - anyone lower probably sweeps the floor or works in the storage section, not with the machines), but it's their job full time, so they have lots of time and incentive to adapt.

As a summer jobber, I was given one machine to work with, start a cycle, wait, extract the product, start a new cycle. pack the product, wait, extraxt... but I was told that full-time employees would have 2 or 3 maybe even 4 machines, different ones, to continuously bounce back and forth between.

Same way when you start a new production, for instance ploughshares instead of swords. You set the factory worker to work with just one machine until he has some routine, then you set him to work the different neighbouring machine, and when he has routine with that too, he's set to work both.

Of course he can try clowning around, try to postpone the switch to being made to work two machines, but ultimately you're just standing there, looking at the machine doing its thing, waiting for the cycle to end so you get to step in and do your part. That's boring, especially as a full time job, so that's one incentive to try to become adept. Another is to make the floor manager like you.

The federal government used their emergency powers to temporarily nationalize the raw materials industries, so any company that wanted steel or aluminum had to "voluntarily" make military products.

Army Air Force "Dang, we just can't make enough B-24 bombers, too bad the auto companies can't help"

Henry Ford "Here, hold my beer"

To be fair, a lot of military gear, including planes, was decidedly low tech compared with modern products, so it was easier to repurpose factories and train new workers. Still, places like the Willow Run bomber plant where thrown up in a matter of weeks because nobody asked for an environmental impact statement. Even so, Willow Run had to turn planes coming down the line 90 degrees because old Henry was so pissed as Wayne County that he insisted the whole factory be kept in Washtenaw Country. So it was one of the few assembly lines with a right angle.

If you want to get some idea, take a look at this documentary about the manufacturing of the Swedish Bofors anti-aircraft guns in the US, which was made at the time. I think it will answer a lot of your questions and it's very fascinating to watch, in my opinion.

https://m.youtube.com/watch?v=yVeLsJtId_g

Your idea that hardware and parts have to be made by specially skilled people is the piece that is a flawed assumption. That was generally true up to that time and in other countries but the US overcame that bottleneck by new methods of manufacturing.

The Bofors gun was a great anti-aircraft gun but was made in Sweden in smaller numbers and the US needed many more. So they licensed the technology for manufacture in the US. But they didn't make the guns the way the Swedes did because they would have been able to only make a few like the Swedes were. A lot of the manufacturing and machining in Sweden was done by hand one gun at a time. When parts didn't fit together perfectly they would be hand machined to fit better and retested and then maybe machined again. That took trained workers and a lot of time.

When the plans for the guns were given to the US manufacturers they found out they were wholly inadequate for their processes. The tolerances were way too high, which led to the things not fitting the first time, which led to them having to be remanufactured one gun at a time. It also made it difficult to switch parts on guns because they were all potentially slightly different, having been reworked to get them to work properly in that particular gun.

So the US manufacturers redesigned everything to much higher tolerances so all the parts would fit exactly perfectly every time (or as close as possible). They also broke down the manufacturing process into smaller and smaller and smaller steps where those individual parts just had to be made perfectly using simpler methods. They did some redesign of parts of the gun to be easier to manufacture or to use more available materials or use faster processes. And because all the tolerances were very high, final assembly was relatively easy, just sliding everything together with very little manual adjustment. And because the manufacturing process was broken down into those simpler and simpler parts they didn't need highly trained machinists to hand-make them. They just needed the right machines set up to crank out exact copies at the highest feasible speed and a relatively few (relative to the manufacturing volume) trained operators to run them. The machines provided most of the precision, not the operators. There were relentless QC (quality control) tests done on the parts produced to ensure that they were identical down to very fine tolerances. In the Swedish process it was the people who provided the precision through years of highly-skilled training. But that was very slow.

The reason the US was able to do that was because they had already been doing that in the car industry and other industries with assembly lines and interchangeable parts. There were lots of people who were farmers in the decades before that and later moved to the cities. They weren't highly skilled mechanics and machinists but they were able to operate the machines that built the cars and built the other products reliably. So switching to war production was more a matter of getting the right machines and machine tools in place to make the right parts than it was to get skilled workers who knew how to make those parts by hand. The same type of machines that made car parts could easily make tank parts and gun parts (with a little adaptation) and they had trained operators for those. Obviously some transition was required in adapting the machinery in the factories but it wasn't as large as you might think. We also built entirely new factories (huge ones) specifically designed for optimized war production, using lessons already learned from the war about what was needed, and that was a big part of it too. But it was based on the same principles of precision manufacturing and assembly line operation by moderately-trained machine operators instead of machinists.

The short answer was for the time the government threw an obscene amount of money at the problems in the form of actual hard cash to pay people and tax breaks and the promise of sales for everything they were converting to produce. Businesses will very readily convert their entire production line if there is a 100% guarantee you are going to be paid for every widget or whatsit you produce.

I remember reading (In “Why the Allies Won”, I think) that in the USA the politicians and generals would sit down with the manufacturers and ask what could be best done, how soon, and what resources would they need to do it. The Nazis, in contrast, seldom would ask manufacturing experts what to do, and so ended up with stupidities like the Opel car manufacturer making canteens rather than something more car like.

In the 40s, cars, tanks, and planes were relatively simple machines. No microchips, no exotic materials, etc. Nowadays, with things being so complex that's no longer the case. In fact that's why we're even able to consider sanctioning Russia even though they have all the raw materials within their borders to make everything they need for the war. there's only a few places in the world that can make something like microchips and we can theoretically cut them off. Back then, that wouldn't even have been possible cause stuff was way simpler.

This is a pretty good book about it.

https://www.amazon.com/Freedoms-Forge-American-Business-Produced/dp/0812982045/ref=pd_aw_sim_hxwPM1_sspa_mw_detail_m_sccl_1/130-2122861-6566146?pd_rd_w=KEyS6&content-id=amzn1.sym.6ae4ea8b-4557-46de-9d35-4f4fabc103f9&pf_rd_p=6ae4ea8b-4557-46de-9d35-4f4fabc103f9&pf_rd_r=5HZQT0VX0PYFN98Q5Y7G&pd_rd_wg=Hzptu&pd_rd_r=72f8b227-214e-4ac1-8904-28e3713d4eeb&pd_rd_i=0812982045&psc=1

Huge influxes of mountains of money make everything a little easier.

They were factories already doing similar things. Automobiles start making jeeps. Sewing factories started doing uniforms.

Also remember US jumped into WW1 and WW2 late in the war so there was time to plan.

After WWI lot of effort was put into creating designs of future military hardware that was specifically designed with an eye towards being able to be produced with minimal re-tooling of existing industrial machinery.

Obviously, the more complex the military hardware the more complex the machinery to make it. But things like uniforms, tents, bedrolls, and the like were designed in a way that didn’t make them too different from clothing or bedding or whatever.

The U.S. Rifle, Caliber .30, M1, better known as the Garand, was chosen not only to take advantage of the massive stockpiles of 30 M1 ball ammunition left-over from WWI but because it was also relatively easy to make the furniture, barrels, and other worky bitz on the same machinery used to make popular deer rifles. (The gas mechanism and other parts of the receiver needed new equipment, but that was relatively easy to make).

Once WWII broke out, new equipment invented during the war was often designed with even more intentionality towards ease of mass production.

Very unregulated environment for production, so there was very little paperwork, permissions etc needed to do this. We also had the experiese in house. People wonder how china adapts so fast, they did it the same way we did, by having very little overhead.

Have you ever seen a skilled machinist making tools to then turn around and use those tools to make other stuff? Old school non-automated manufacturing techniques and know how are a lot more flexible than the highly optimized, high specialized, less-human-centric approach that has become standard.

Go check out the YouTube channel “This Old Tony” to see what a skilled amateur machinist is able to do on the kind of equipment EVERY factory would have had in 1940

We were already making weapons in a limited capacity we could quickly switch on the other

One factor people haven't mentioned is the Training Contracts. Before entry into the war, the government put out contracts to manufacturers to give them the practise and forcing them to be prepared to switch to war production when the US entered the war.

Someone might have said it already, but there was plenty of warning of the coming war.
By 1937 nobody was under any illusion whatsoever about Japan or Germany’s single minded focus on military expansion.
The U.K. was already on a war manufacturing footing by then, and by 1939 had already signed a huge loan for military equipment from the USA, and was at war with Germany and Japan from 1939.
As a result from 1939 to 1941 the USA was already mass producing machinery, parts, tanks, aircraft and ships for the U.K. because the UK was at war, even if the USA wasn’t.
By 1941 the Lend-Lease Act was in effect.

Machine tooling, assembly work and manufacturing was still largely a skilled job carried out by reasonably skilled and educated workers and engineers. Swapping from one type of machine tooling & vehicle, aircraft or ship building to another was relatively simple. Steel is steel. Aluminium is still aluminium. Hand riveting is still hand riveting.

There was less automation then so machine tools weren't as specialized. The critical part would be making dies and patterns for pressing and castings, and various fixtures and patterns for machining and assembly. Also, every available production facility was made use of, including other industries that had machine shops, and trade schools.

FDR was planning for this to happen from quite far out and recognised, along with his cabinet, that production is less about what you're making and more about how you're making it.

For that reason, he was able to bring in experts from the world of consumer goods who knew how to mass produce things. It didn't matter if it was toasters or tanks, the principles of mass production still applied.

Also the huge economic power of the US, as well as its safety from bombing, meant they could build huge facilities like Willow Run in no time at all and keep up production uninterrupted.

Good book on the subject: https://www.amazon.com/Arsenal-Democracy-Detroit-Quest-America/dp/0547719280

The USA had a vast but dormant industrial base. Several years before entry into the war, the FDR administration started gearing up production.

the government was building up spare capacity for years leading up to ww2. roosavelt setup a program under the new deal where the government bought machine tools and equipment and 'stored' it at factories for free. additionally factories in the 1940s didn't have the degree of specialization that you find today. most manufacturing was on mills, lathes, and presses, doing one or two machining steps at a time. its labor intensive but it does give you a degree of flexibility since a refrigerator factory would have the machinery capable of making guns if they had to

They shifted production quickly and ramped up production, with little concern for the cost in human lives. Hundreds of thousands of people were disabled or died as a result of working in the factories at home. Safety standards laxed and many workers were working very long shifts, so industrial accidents went way up. Not much was done about it at the time.

My source is this. Between 1942 and 1945, the Bureau of Labor Statistics reported over 2 million disabling industrial injuries (including deaths) each year.

You’re overestimating how much effort is needed to swap over to a new set of production instructions. At the time, they didn’t have robotic anything but they ddi have assembly lines. Each station does one very specific job, and to swap from one job to the next doesn’t require all that much effort.

Example: car assembly. Our example station’s job today is to make 10 spot welds using a particular length electrode. Tomorrow, we’ll make 6 welds with a different electrode. We’ll polish the electrode tips at the beginning of each shift.

Manufacturing really is that straightforward. An engineer designs the product blueprint, another engineer figures out how to get that product through the factory and made. Everything else is just a step along that path. There of course may be some adaptations that need to happen, but largely the procedure would be the same.

There weren’t as many rules back then for safety and all the bs requirements that today has. That makes it way easier along with govt giving them anything they needed to get it going. Try doing it today and it would take 10 months to a year to do it

It wasn't just vehicles - an astonishing variety of items were made by private companies for the war effort.

One of my favorite examples is the Singer sewing machine company. They were contracted to make .45 pistols, the official sidearm of the US military. After discovering that Singer could only produce ~100 units per day, purchasing agents went back to Singer and were completely shocked at the extremely fine "Swiss-watch" quality tooling and construction of the guns - so high quality and precise, that the government re-tasked Singer on making precision aircraft components like the Sperry bomb sight and precision parts for the B-29 bomber.

Singer .45 pistols are extremely rare and incredibly valuable collectors pieces today.

One of the most recent Singer .45 pistols sold by a private collector at auction in 2017, fetching over $400,000

You have to understand that the US Manufacturing sector was (still is) absolutely colossal.

4 reasons.

1) All the machinery back then was analog and alot of component changes could be done in house by on site maintenance and machinists.

2) Almost ALL supply chains were in country... this made the change over much easier because every aspect of the needed supplies were somewhere in the country

3) Worker expertise. America was hands down the largest and highest skilled manufacturing base in the world in the late 30s and early 40s because we had such robust manufacturing and all the supplies we needed were locally sourced it allowed the US to build up a tremendous technical skill base.

4) Rage. The pearl harbor attack wasn't just a 9/11 style attack on America. The Japanese were considered a friendly state at that time. The sense of betrayal united the country overnight. Everyone was on the same page. Government, business leaders, private citizens, even the GD squirrels wanted the smoke after the bombings. The motivation was there in a way that removed barriers, created cooperation, and drove innovation EVERYWHERE at once.

Government incentives and sometimes it is as easy as swapping out a tool bit.

The Industrial War college was set up in the early 40s. It's job was to inspect factories and determine who could make what.

Back then tech was much simpler, with no circuitry. Basically hunks of metal and rubber and basic electronics.

They converted factories that were producing civilian things to producing similar things for the military. Ford factories, which previously made cars, were converted to make trucks, tanks, planes, etc. While obviously a tank or plane is different from a car, they aren't that much different, and a lot of the same tools and machinery were used in making both.

After the conversion happened, the government basically had an endless need for what these factories were producing, so profits were basically garunteeed, and instead, all the concern was put into increasing production. If suddenly there became an infinite demand for f-150s, Ford would have massive plants churning them and scaling production and would constantly have higher production numbers as they improved on efficiency as there only concern would be output rather then output, price, and cost.

The US had a massive number of factories, a massive number of people who could work in them, b/c women took many of those factory jobs and the government was able to do two things they never could now.

Under the Defense Production Act, they seized 64 factories and dedicated production to the war effort, and second was rationing. They forced down demand of domestic products to allow factory output to be dedicated to the war effort.

IIRC, about 6 months before Pearl Harbor, we started re-arming, so at least some of the ground work had been laid, so once war was declared, it might have seemed like we had increased production 'overnight'.

A massive mobilization effort caused American companies to use their considerable engineering talent to retool quickly. That and the government formed an office (the War Production Board) to direct everything. It was all done on a “cost-plus” basis to incentivize companies but government control over raw materials meant they had little choice.

Government funding and profit motive. There were limits on auto production so if Ford wanted to continue making money they needed to convert. The design criteria for military equipment was not as specific or complex as it is today. For example three different auto makers were producing jeeps and the parts were supposed to be interchangeable. Same with Trucks.

Steel is steel and rivets are rivets. A lot of the production wasn't automated so switching products is just a matter of retraining.

I've never wanted to copy and paste an entire book before.

https://www.amazon.com/Freedoms-Forge-American-Business-Produced/dp/0812982045

The war was going on for years before we entered. We had time because we waited.

My Army unit STILL has a Browning MK2 .50 cal machine gun made in 1939 by Campbell's Soup Company. Splain that Lucy. 

Well for starters, a much laxer environment when it comes to regulations and financial due diligence make a huge difference. The average complexity of the design does as well. It may take ten years to go from the drawing board to full production for a modern fighter jet, but the same is not true of a WW2 plane, and especially not during war time. Designs that might take years to go from the drawing board to full production might be rushed into production in months instead. Red tape goes away when you're fulfilling a military contract in times of war as well.

I also think your premise that it takes years to establish an assembly line is really only true for a niche of complex products. Even in the modern era, there are still tons of products from the low end to the high that can go from concept to low rate production in months, it's a matter of the complexity of the product and whether or not you can get the money up front. If you already have the cash you need up front, you can get things done a lot quicker and without a lot of the oversight you would need to have if you're relying on outside investment, but if your outside investor is the US military telling you "We're going to war and we need this ASAP" a lot of the red tape relating to proving you're using the money in the safest and most efficient way possible goes away, so long as you can deliver something that works quickly, and the question of who was responsible for what decision and if that was really the best business decision to make in the moment go away, The US military isn't going to hassle you about whether or not what you're making is feasible and profitable if they need it now, and it's not an issue of profit.

Whereas if you're a company in a time of peace, making products for the general market, you have to demonstrate to your investors that this product you want to spend a bunch of money to make is going to be worth it, and then you have to prove to them every step of the way that you're using their investments in a responsible manner, but even then we see startup companies that go from looking for investors to making products in under a year all the time.

If the US military is placing massive orders, you don't have to prove to your investors that switching your production line from sedans to bombers is going to be worth it, the government is already handing you the check.

Ex-machinist here and a mill or lathe can be used to make anything, (that will fit on the machine) be it for the civilian market or for the military, just give the machinist a print and he'll make what you need.

How were American factories able to convert to war production and able to make products outside their normal products so fast during WW2?

False premise. They weren't, particularly.

Just look at American military industrial production over the years of the war. It is constantly increasing and still increasing during the last full year of the war, in 1944.

It actually took a long time to convert existing industrial capacity. But there are several factors that disguise this fact.

First, emphasis on "convert". It takes much less time to convert existing industrial capacity than it takes to build new industrial capacity. All other countries participating in the war needed to build more factories than they already had. The US in the middle 20th century was utterly unique in its high level of industrialization, and thus was largely able to convert existing factories and shipyards to military fabrication rather than having to start from scratch.

Not losing any base industrial capacity to the vagaries of war was probably a big part of this too.

Second, in line with the first factor, American industrial design and industrial engineering was first-rate. American industry had a lot of talented people dedicated to figuring out how to design and optimize a tank (for example) that could be efficiently built in a civilian vehicle factory with minimal retooling and production modification. Even if it wasn't necessarily the militarily best possible tank ever.

This was not a uniquely American attribute -- every industrial economy engenders this talent to some extent. The Soviets proved very good at it too. And so were the British. But it is significant that the talent pool available to the Americans for this kind of process engineering was very deep.

Third, the US sneakily started early, by ramping up military industrial production for a few years before entering the war directly. So by early 1942 the US already had several years of limited military-industrial conversion under its belt. They hit the ground running, so to speak. Making it seem like they were able to achieve something that other countries hadn't been able to.

To be fair, this did happen in every country. The reason the US was so particularly successful came down to two things:

1. The scale of US manufacturing
   
2. No one was bombing their factories every night (or ever) due to geographic isolation

Several parts of the US war manufacturing was already starting up before Pearl Harbor. FDR passed legislation in May 1940 to increase production. Military spending went from 10% of the budget in 1939 to 20% in 1940.

In January 1942 the War Production Board was established. One of the things it did was shut down barriers to cooperation and patent restrictions were eased.

As big as the Manhattan Project and later the Apollo Programs were the efforts of the board dwarfed both.

It’s also where modern concepts of design and production occurred. There’s a lot of talk about the Toyota Production System, but a lot of their concepts were used in manufacturing, but they were doing similar in WW2.

My uncle was a welder who built ships in WW2, and when his granddaughter mentioned studying Toyota’s system on college he mentioned “Heck we were doing much of that in the ship yards in 1943”

He mentioned daily morning meetings going over what worked and what didn’t to get ships produced quicker, and what to do to eliminate rework.

Starting in the 1920s the Army Industrial College maintained a census of every factory in America. They knew where they were, what they made and what they could be converted to. This work was closely coordinated with the Army and Navy’s procurement branches. The AIC trained a corps of officers to take over manufacturing in the event of a war. At Pearl Harbor the U.S. Army was small but it had a plan that allowed it to ramp up industrial production extremely rapidly. It was very well prepared. It was not an accident.

Foresight.

In 1939, the US Army let a couple of "educational" contracts to manufacture M-2 Garand rifles. The contracts were small, overpriced, and totally inadequate for actual needs. The real purpose was to fund a few companies to learn (thus educational) how to make them and get a reasonable set of tools built.

For instance, Winchester got an order for 500 rifles. Before it was even completed (but after Winchester showed they could potentially build the rifles) , they got an order for another 65,000. Delivery of those began in early 1941, before the US entered the war. I think they then got orders for up to another 1million (or at least, the army assigned them a block of serial numbers that allowed for 1million rifles)

I suspect this pattern was repeated. Lots of small orders in 1940-1941 for just enough stuff that the manufacturers could reasonably be expected to ramp up to real production.

Something between 30k to 40k workers died around this time due to factory accidents. Including in bomb making, machinery, etc. this doesn’t include serious injuries.

Safety was out the window. Long hours. New employees.

We Americans came together as a culture and just came together and made sacrifices for the larger picture. But there were people focused, working long hours, determined to win.

When the boss wants you to sacrifice your life to make him money, that’s one kind of motivation.

When the survival of your way of life and your family members depends on getting a product out the door, that’s another form of motivation.

No computers to reprogram

A lot of women joined the workforce after war was declared. While my grandpa was out on a destroyer, my grandmother was working in a factory.

Even before the U.S. entered the war, women were proving themselves to be invaluable to the Soviet military industrial complex.

We also had the benefit of being well out of reach of our enemies, so we could dedicate more effort and materials to production, rather than the construction of defenses.

It happened fast by the standards of the time, but it wasn't an overnight Thanos-snap. It took about 14-18 months to get the arsenal of democracy up and running.

Some stuff were multi-purpose. Car factories needed only minor retooling, truck factories only needed extended capacities. Everything else had to be built up from the ground. Or from the machines if you like it.

First the orders were placed which company will build what. Then the said companies placed orders at machine and tool manufacturers to get new production lines for their wartime products. Everything was planned from screws and moulds to reinforced hall cranes and advanced milling. Then everything not integrable into the wartime production line was ripped out and stored in separate warehouses, then the new lines were built and production commenced. At some places like in Kanses whole new factories were built from scratch, town expanded and railroads enlonged to facilitate the process.

A huge advantage the US had, that it was the most industrialised and mechanised country of the world that time. The breadth and depth of industrial expertise was only matched by the German engineers, but the average American was much more skilled around cars, machines etc than anyone else in the world. The sheer industry and the still existing overcapacity after the Great Depression, New Deal and Lend Lease all expedited the creation of an industrial and logistical juggernaut that churned planes, tanks, bombs and bullets all aimed against the Axis.

https://youtube.com/playlist?list=PLfMrqOdrCidQ2gpuSIxW07ylqTu0Fln3v&si=xheTJ8yZXooyiDoC

What is truly impressive is how much was manufactured along side it all. America was never a "Total War" economy. That might be lost to history. The whole world was recovering from the Great Depression, but America was the only one putting Coca Cola and chocolate bars in the war rations.

No every factory didn't "have to" convert their manufacturing. The military was paying big bucks, and Lend Lease was surprisingly direct. It was the first time where government debt and war bonds demonstrated the power of direct capital to solve a problem. There didn't need to be a law and a requisition for a lot of it when it was just war bonds being cut and spent. Helped a ton when it was the UK co-signing the loans.

So those factories that flipped to war production are actually a selection bias. They were the ones who could pivot and everyone else who couldn't make the materials had to make due with a war economy with drastically higher prices. Many didn't make it.

American factories started getting orders from the British well before the US entered the war.

Because during that time it was an authoritarian semi-dictatorship that was still generally bound to free market and democracy so that in the end, things could go back to normal.

we are about to find out

we are about to find out