The Precision Revolution.
I just returned home from a two week
trip through New England, a part of the U.S. that I had never visited before. Most of the
trip was a tour sponsored by Road Scholar. The focus of this tour was mainly the
development of the first railroads in New England, and the effect of this on
the economic development of the region.
The "take away" message
was that after the completion of the Erie Canal in 1813, New York Harbor had a direct connection to
American interior markets, putting all other East Coast ports at a
disadvantage. Baltimore responded by
building the Baltimore and Ohio Railroad.
Investors in Boston, still the
busiest East Coast port, responded with a flurry of efforts aimed at
building a rail link from Boston to the St.
Lawrence River. These efforts eventually connected rural New England to the rest of
the world.
But the most interesting part of the
tour and lecture series was a visit to the American Precision Museum in
Windsor, Vermont. This National
Historic Landmark is built around the old Robbins and Lawrence Armory, an 1846
gun factory, originally water powered, built along the upper Connecticut
Valley. At first glance, it looks like
a typical musket factory, with the
interior walls lined with display cases filled with old guns bearing labels
such as: "The first Sharps
Rifle", or "The first Enfield
Rifle." (Wait a minute. Wasn't the Enfield a British weapon? It was, but the tooling to produce it was
made in Vermont, as were the first few hundred rifles. Then these rifles were shipped to England,
along with the tooling, where they were made thereafter.) In fact, that was the business plan: To work with the customer to design a rifle;
design and build the tooling to make the
product; make a few hundred to assure
that the tooling worked; and then turn
the whole operation over to the customer or some third party for actual
production, so that they could
concentrate of the more highly skilled and lucrative activity of just designing
and building tooling.
After a few minutes in this place,
the historical significance of this enterprise began to sink in. This is the place where mass production
began. You see, Robbins and Lawrence
were making rifles with interchangeable parts, and were one of the first, if
not the first, to do so successfully. Eli
Whitney had had the idea to do this in the War of 1812, but due to the exigencies of war he was not
allowed time to first build the tooling, and then build the muskets. Nor could he explain to the customer just
what he was trying to do, and why it took time to do it. And even if his persecutors in Congress had
understood the issue, they could not have given him the time anyway, since we
were at war and time was not to be had.
But in 1849, The Army gave Robbins and Lawrence a contract for 10,000
rifles, and three years to fulfill it.
In the first year they just designed the tooling. In the second year, they built the
tooling. And in the third year, they
made all 10,000 rifles, with interchangeable parts. The era of mass production had arrived.
But for this revolution in
production to occur, there first needed to be a revolution in precision. (Hence the name, American Precision Museum. ) As long as things were made one at a time,
there was very little attention paid to precision, except that each part had to
be the right size to fit to its mating
part. But exactly what size that
was arbitrary. I used to own a small
machine shop, and I still have a few old lathes, mills, and drill presses. If I am making some one-of-a-kind object for
my own use, and someone asks me,
"What size is that shaft?" I
might reply, "Whatever size will fit that bushing." So they ask, "So what size is the
bushing?" and I reply, "Whatever will fit that shaft."
It the 18th century, some Englishman
built a watch so perfect that it could be used for navigation. Surely, this had to be a precision
device. Yet it was precision only in
the sense that each part had to fit its mating part. As long as it did that, its actual size was
unimportant. But to have the advantage
of mass production, where each worker is set up to make only one part, and will make thousands of them before he has
to stop to change set-ups to make a different part, then you need parts that
conform precisely to some pre-determined standard. And you need measuring instruments, (gauges) to check them all to make sure that
they do. And these gauges have to have
an even higher standard of precision.
These challenges required a whole new way of thinking, and new
techniques and methods, before the benefits of mass production could be realized. And these methods were first worked out, not
in England, but in New England, in the
upper Connecticut Valley, in the 1840s.
If you ever have a chance to visit that part of the U.S. , take the time to visit this museum. They still have some of the old machinery, as well as docents who can tell you about it. Probably the prize of their collection in a
machine which Robbins and Lawrence built in 1853 for cutting rifling groves. With the pull of a single lever, you can cut
a rifling, index the barrel 1/5th of a
turn to cut the next one, and after all 5 cuts, advance the tool bit for the
next pass. And a single adjustment will
give you any desired rifling pitch in twists per foot. They also have a machine, (shown below) which is an early form of profile mill which allows a milling cutter to duplicate a pattern.
