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No. 1826:
Eccentric Circular Turning

Today, eccentric circular turning. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Henry Bessemer received a patent for his new steel-making process in 1855. But the nineteenth century invented Bessemer as much as the other away around. For this was the age of steel. And, along with the hugely expanded use of steel came new means for shaping and machining it.

Consider, say, a problem connected with planing a piece of steel to a desired thickness. The cutting stroke needs enormous force and it must be done slowly. But you want to return the cutter for the next stroke as quickly as possible. All kinds of quick-return mechanisms appeared. A steadily turning crankshaft might drive a cam or eccentric gear. During one cycle the cutter moves slowly in one direction and rapidly in the other.

The latter nineteenth century offered vast literature on the elaborate mechanisms that made up heavy machines. And nonsymmetrical, or eccentric, action was at the heart of it. Now a colleague has shown me an old book by John Ibbetson, titled, Eccentric Circular Turning. This book went through many editions and printings between 1817 and 1851 &mash; all long before Bessemer and big steel.

Ibbetson's family had been lathe-makers in the eighteenth century, and John Ibbetson had developed the new eccentric chuck. It drove a cutting tool through preset sequences of cuts, each a bit different from the last, until it returned to a starting point.

PatternPatternThe output was an elaborate and quite lovely decorative carving. These carvings took forms that might resemble snowflakes, or maybe fancy tile work. Today, chaos theorists generate somewhat similar patterns — although theirs never return to a starting point. Ibbetson's interest was completely ornamental. He illustrated his book with copperplate engravings that he'd carved directly with lathes, equipped with his eccentric chucks.

And he was no doodler, working in isolation. He cited previous work by the French, and based his work on that of the German, Holtzapffel. If you know this kind of mechanical decoration, you've heard Holtzapffel's name. He was its major developer, although you find antecedents all the way back to sixteenth-century Bavaria.

However, Ibbetson so catches my eye because his book on decorative art has the look and feel of Bessemer's world. He calls to my mind the artist and designer of steam forges James Nasmyth. Nasmyth invented the heavy steel forges of the mid-nineteenth century, but he's also known for his lovely paintings of those forges.

Reading Ibbetson we catch the same seamless symbiosis. He sees no line between decorative art and machinery. His machine itself is art, as much as the pattern it produces. And we gain a clearer picture of the forces behind the new industrial world.

The driving force was then — as it has always been — more aesthetic than utilitarian. But then, invention has always been driven by the magnetic attraction of beauty, in its many forms.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

J. H. Ibbetson, Specimens in Eccentric Circular Turning with Practical Instructions for Producing Corresponding Pieces in the Art. 3rd ed., London: Longman, Ormé, Brown, Green and Longman, [Probably 1838, although new 3rd editions kept coming out until 1851.] All images on this page are from this source.

I am grateful to Bobby Marlin, UH Library Archives, for suggesting the topic, and for generously providing material from Ibbetson's book.

For a twentieth-century look at mechanisms, see the treatise: Ingenious Mechanisms for Designers and Inventors. (Franklin D. Jones, ed.) Vol. I-IV, New York: Industrial Press Inc., 1968. My thanks to Lewis Wheeler, UH Mechanical Department for this fine set.


Compound eccentric chuck