P&Q Hall of Fame Profile: Nathan P. Stedman

Editor’s note: Four men will be enshrined in the Pit & Quarry Hall of Fame during the March 28 induction ceremony in Nashville, Tennessee. Nathan P. Stedman, a member of the 2021 Hall of Fame class, is the subject of this profile.

Stedman

Although some of the history behind the cage mill is lost to time, there’s no debating whose name is tied to the 19th century development that is, perhaps, as relevant today as it was when invented more than 135 years ago.

The name is that of Nathan P. Stedman. Stedman was an Indiana manufacturer who joined his father in their family business in 1867. He took over the business upon his father’s death in 1884 and ran it, for many years, with his two sons.

According to Stedman Machine Company, which continues to operate more than 185 years after it was founded, Stedman began producing fertilizing and rendering machinery in 1885 as part of a company expansion. The very first cage mill – or “disintegrator,” as Stedman originally called it  – that sold was a 42-in. model purchased by the Oakland Pressed Brick Co. of Zanesville, Ohio.

In Stedman’s own words, the cage mill he invented was “a certain new, useful and valuable improvement in disintegrators,” that was “employed in disintegrating or pulverizing ores, clay and other substances.”

Chris Nawalaniec, president of Stedman Machine Company today, offers perspective of the cage mill’s lasting impact.

“The essence of the invention is it’s very efficient – in terms of energy and operating costs – at producing a high volume of finely ground limestone,” Nawalaniec says. “That’s something that still holds true. In most cases for agricultural lime, the cage mill can produce material on spec one time through the machine, so you don’t have secondary processes. It’s part of being a good, efficient machine.”

That the cage mill remains a leader in efficiency is a tribute to its inventor, according to Nawalaniec.

“In the aggregates industry, the cage mill was helpful in a lot of cases because fine material was not desirable,” Nawalaniec says. “But if you can make the right size fine material and have the right rock chemistry, the cage mill has been a very useful and profitable tool to the aggregates and mining industry to produce agricultural lime.”

Innovator and businessman

Nathan P. Stedman received a patent for the cage mill crusher in the late 19th century. Photo: Stedman Machine Company

Before Stedman’s cage mill, Nawalaniec suspects salvageable material was likely lost as waste. Or, it could have been handled with more expensive types of equipment that were either more labor intensive, costly or required added energy to produce finer material results.

Cage mills aren’t very complicated machines, Nawalaniec adds, but they remain a top-selling product at Stedman Machine Company. In fact, Nawalaniec says the company is eyeing further investments in Stedman’s signature development for the coming years.

“This product development project we’re working on now for finer grinding has the ability to replace much more complicated, much more capital intensive equipment,” Nawalaniec says. “We have the opportunity to displace some other machinery to replace machinery for even finer grinding.

“If you can do more with them – which we fully expect to be doing – then I think there’s a very good future for cage mills,” he adds.

According to Stedman himself, the object of his invention was to provide a double-cage disintegrator with a frame that allowed for cages to be separated. Stedman wrote in 1893 that the construction would allow for cleaning and repair, as well as provide a means to counterbalance the cages so users could avoid uneven bearing wear. 

Stedman attempted to capture the uniqueness of his cage mill in the patent application he filed for the cage mill. As he wrote more than a century ago: “What I claim as new, and desire to secure by letters patent, is … in a disintegrator, the combination with a base having a series of openings along one edge two housings mounted on the base and adapted to be moved thereon, each provided with a lateral projection to extend over the said series of openings and form a fulcrum for a lever which is adapted to obtain a purchase in one of the said openings by means of which the said housings are moved, the latter carrying the cages, and means for securing the said housings to the base in the required position, substantially as described.”

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