INVENTORS WE MUST DEFINITELY KNOW ABOUT

“If I have seen further,” Isaac Newton wrote in a 1675 letter to fellow scientist Robert Hooke, “it is by standing on the shoulders of giants.” Innovation and invention do not occur in a vacuum. Inventors and thinkers from Da Vinci to Thomas Edison to Steve Jobs liberally used inspiration from the doers and thinkers who came before them.

The Machine Tool industry is no different. Early versions of machine tools included bow drills and potter’s wheels, which had existed in ancient Egypt prior to 2500 BC. Lathes are known to have existed in multiple regions of Europe since at least 1000 to 500 BC.

In this issue, we would like to pay tribute to Henry Maudslay, an English machine tool innovator, tool and die maker, and inventor. He is considered one of the founding fathers of machine tool technology. His inventions were an important foundation for the Industrial Revolution.

Maudslay is best known for his screw-cutting lathe, which he developed and perfected by 1797. Machinists had been cutting screws on lathes for centuries, but it was a laborious and uncertain process, with a cutting tool guided by hand and no real way to ensure a consistent pitch for the thread. Because of this inconsistency, every thread was slightly different, and a nut made to suit one thread would not fit any other.

Maudslay took the separate inventions of others, added a few of his own, and incorporated them all into one unified machine. In his newly designed machine, the cutting tool was not held by hand but fixed into a slide rest. The slide rest was fitted onto a long lead screw that ran parallel to the stock and was driven by the lathe so that the tool automatically moved along as the piece turned.

To produce the desired pitch (threads per inch), Maudslay designed a set of replaceable gears that drove the lead screw. Once the proper gears were inserted and the cutter was locked into place on the slide-rest, the operator could cut a thread on a rod, and then he could cut hundreds more just like it, and they were all truly interchangeable.

Before the development of Maudslay’s lathe, which became the first to be used widely in manufacturing, each screw or bolt was a unique item that had to be matched with a unique nut. Every bolt and every nut had to be marked as a matching pair. The process of matching bolts and nuts in the construction of complicated machinery proved to be time-consuming, arduous, and expensive. Any machine that needed repair and had to be disassembled would become a nightmare of mismatched screws and nuts.

In his autobiography, James Nasmyth, inventor of the steam hammer, who worked as an assistant in Maudslay's workshop, noted: “None but those who lived in the comparatively early days of machine manufacture can form an adequate idea
of the annoyance, delay, and cost of this utter want of system, or can appreciate the vast services rendered to mechanical engineering by Mr. Maudslay, who was the first to introduce the practical measures necessary for its remedy. In his system of screw-cutting machinery, and his taps and dies, and screw-tackle generally, he set the example, and laid the foundation, of all that has since been done in this most essential branch of machine construction.”

To prove the perfection of his device, Maudslay used his screw-cutting lathe to create a screw that was five feet in length and two inches in diameter, with 50 thread cuts per inch. The accompanying nut was 12 inches long and contained 600 thread cuts. Although Maudslay’s early version of his lathe required a machinist to take the lathe apart to change settings, later he added design improvements that allowed the operator to alter settings by simply switching removable gears.

Maudslay’s mechanical advances were important because he developed a machine that could be used to build other machines. Because his lathes could cut tool steels, engineers who later improved upon his work were able to supply greatly needed consistency and precision in a wide array of industrial machine parts. Industries that specialized in precision manufacture like machine tool manufacturers, tool and die makers gunsmiths, clock makers, builders of telescopes, and navigational equipment, etc. were also aided by Maudslay’s inventions.

There is an original Maudslay screw-cutting lathe on display at the Science Museum in London.

Tech Talks is a column by industry veteran and journalist Reji Varghese that talks about the latest advancements in Machine Tools, provides snippets from history, interesting facts, etc. about the Machine Tool industry.

Reji Varghese

RV Forms & Gears

fngreji@gmail.com