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Necessity, as they say, is the mother of all invention. Smiths, machinists, and clockmakers have long been able to create marvels of engineering by obsessively crafting one one-of-a-kind part to fit another. But as industry has grown through the centuries, the demands of scalability, replicability, and economy have only grown as well. Such growth created the history of micrometry.
Any country smith could fashion a bolt to repair an ailing wagon. They would be able to help a stranger on their way, even if the wagon was of unfamiliar design. But even a highly trained engineer could not recreate the internal components of a broken engine without the aid of precision measuring and manufacturing tools.
As the Enlightenment gave way to the Industrial Revolution, tooling and machining became more beholden to standardization, interchangeability, and scalability. The micrometer quickly became a necessity.
Difficult as it is to imagine, interchangeability and standardization have not always been so essential to machining and manufacturing. Artillerists and arms makers played a large part in integrating such concepts with the work of machinists.
These changes began in the 18th century. Jean-Baptiste de Vaquette de Gribeauval, Lieutenant General of the French Army in the Napoleonic era, is credited as perhaps the earliest advocate of industrial interchangeability. Gribeauval sought to equip the French army with lighter, more reliable, and more effective weaponry. He did so largely by imposing sizing standards for artillery and gun barrels.
Myriad other arms makers would follow his lead in championing interchangeability, including American inventor Samuel Colt.
The first screw micrometer, far larger than the modern handheld design, was invented in the late 1630s. English gentleman scientist and astronomer William Gascoigne integrated the apparatus with his sextant to accurately measure the distance between celestial bodies. Through subsequent experimentation, Gascoigne found he could derive the size of astronomical objects as well. By using the position of the screw and the focal length of the telescopic lens as known quantities, Gascoigne could then derive the sizes arithmetically to a degree that was previously impossible.
The next earliest known micrometer is the subject of some dispute. Attributed to James Watt, renowned Scottish industrialist and inventor, the apparatus is thought to have been made around 1776. The apparatus showed up around a century later in an enormous exhibition of scientific instruments at the London Science Museum.
The actual origin of the micrometer cannot be definitively proven. It was presented as part of a collection of effects associated with Watt’s pioneering work on steam engines. The tooling and wear are thought to be consistent with machinery of Watt’s make and era. However, no identifying markings are present.
Still, the apparatus is significant because it is the first known micrometer consisting of a c-shaped bracket. This marks a big step in the direction of the modern micrometer design that we know.
In the early 1800s, English machinist and industrial innovator Henry Maudslay built his own benchtop micrometer. His device expanded on the concept of using a screw to derive precision measurements. The apparatus even earned a nickname. Folks around his shope called it “Lord Chancellor” in joking reference to its use as an impartial judge in disagreements about the size of parts.
Maudslay also invented a metal lathe capable of producing standard thread sizes for screws and parts. In this way, he helped pave the way for micrometry to become both more accurate and more scalable. Further, Maudslay’s innovations made it possible to create interchangeable screws and parts for the sake of reliable industrial manufacturing. This concept of interchangeability was an inflection point in the history of the micrometer and would drive its demand in tooling and machining operations the world over.
Not long after in 1848, the owner of a Parisian metalworking shop created the first known handheld micrometer. Jean Laurent Palmer sought to obtain accurate measurements of metal wire, tubing, and sheeting for his metal works. Combining the precision screw and the caliper, Palmer created an instrument that bears striking resemblance to the handheld caliper micrometers we have today.
So successful was this design that the name Palmer became synonymous with the caliper micrometer in Europe. The device became generically known as a “Palmer screw” in various countries across the continent.
Providence, Rhode Island firm Brown and Sharpe acquired the patent for the Palmer micrometer in 1867. The company began to mass manufacture the device, and achieved various improvements on the Palmer design, allowing for ever greater precision and accuracy.
As the tool became more widespread, other inventors continued to make more improvements to its design. Notably, Edward W. Morley formulated a series of experiments to scientifically prove the tool’s accuracy.
All the while, the integration of interchangeability and standardization with manufacturing was taking place wherever the Industrial Revolution had spread. Never again would those concepts be divided.
In the 20th century, the manufacturing of micrometers continued to spread across the remainder of the world. For instance, their production was a big part of the post-WWII manufacturing boom in Japan.
Consistent metrology and production are so essential to the workings of our world that it’s difficult to conceive of a time when they weren’t. As industry became more saturated in people’s ways of life the world over, so did the concepts of standardized and interchangeable parts.
The caliper micrometer remains stable in its design, and meanwhile the concept of using a precision screw to measure distances accurately has been adapted to myriad other designs. You will find it in common tools like ball micrometers, blade micrometers, bore micrometers, and depth micrometers.
Today there are many other types of micrometers, with dozens of specialized adaptations for nearly any application. If well-made and regularly calibrated, the micrometer is an invaluable part of the toolbox of any maker who values precision. From professional engineers to machinists to hobbyists, micrometry has never been more accessible as a means of quality control.
Phil Wiseman is Chief Marketing Officer at Alliance Calibration. He earned a B.S. in Chemical Physics from Centre College. Phil is an ASQ Certified Quality Auditor and ASQ Certified Manager of Quality/Organizational Excellence.
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