Lewis R. Heim, owner of The Ball and Roller Bearing Company.
A Problem in Manufacturing
At the turn of the 20th century, industrial manufacturing was undergoing rapid growth. The bicycle industry, in particular, was booming, and with it came a massive demand for precision ball bearings. But there was a problem—existing grinding technology was too slow and inefficient to keep up.
Traditional center-type grinding, which relied on holding parts between two fixed points, required manual loading and constant adjustments, making it difficult to mass-produce high-quality bearing rollers at scale. Manufacturers needed a solution that was faster, more efficient, and more precise.
Lewis R. Heim: The Birth of Centerless Grinding
The breakthrough came from a machinist and inventor named Lewis R. Heim, owner of The Ball and Roller Bearing Company. When his company received a large order for bicycle bearing rollers, Heim realized that traditional grinding methods wouldn’t cut it.
Instead of relying on center holes to hold the part in place, Heim developed a new concept:
- The grinding wheel would remove material from the workpiece.
- A regulating wheel would control speed and rotation.
- A work rest would position and support the part.
From Concept to Industry Standard
At first, Heim’s design used the sides of the grinding and regulating wheels for positioning the part. While this method was an improvement, it wasn’t perfect.
One of Heim’s employees, Jim Daley, saw potential for further refinement. Daley later left Heim’s company to work for Francis Sanford, owner of the F.C. Sanford Company. There, he introduced a game-changing modification: using the face of the wheels rather than the sides.
This improvement became the foundation of modern centerless grinding, making the process more stable, precise, and scalable for industrial applications.
The Introduction of Thru-Feed Grinding
Another critical development came from Francis Sanford himself. He introduced the concept of thru-feed grinding, which allowed for continuous processing of parts without stopping the machine.
By tilting the regulating wheel and shaping it with a concave design, Sanford enabled parts to move through the machine automatically, dramatically increasing production speed and efficiency.
The Patent War: Heim vs. Sanford
As centerless grinding gained popularity, a patent dispute erupted between Heim and Sanford. Each inventor claimed ownership of the process, leading to a high-stakes legal battle that reached the U.S. Supreme Court.
In the end, the court ruled in favor of Francis Sanford, granting him the patent rights to thru-feed centerless grinding. This decision solidified Sanford’s contributions to the technology and allowed for its continued industrial development.
Early Skepticism & Eventual Acceptance
Despite its revolutionary potential, centerless grinding was not immediately embraced by manufacturers. In fact, during the 1920s, some part drawings included warnings like:
"This part must be round – Not to be centerless ground."
Many engineers were skeptical that the process could achieve the same precision and quality as traditional methods.
However, as the automobile industry expanded and demanded high-volume production of precision parts, centerless grinding proved its value. It quickly became an essential technology for automotive, aerospace, and industrial manufacturing.
Centerless Grinding Today: Pushing the Limits of Precision
Over the decades, centerless grinding has evolved into one of the most reliable and precise machining processes in the world.
Modern centerless grinding machines are now capable of achieving roundness tolerances of less than 10 millionths of an inch, an unimaginable level of precision in Heim’s time. The process is now used for manufacturing everything from medical implants and aerospace components to high-performance automotive parts.
A Lasting Legacy
What started as a solution for bicycle bearings has transformed into a cornerstone of modern manufacturing. Thanks to the ingenuity of Lewis Heim, Francis Sanford, and countless engineers who refined the process over the years, centerless grinding remains one of the most efficient, accurate, and widely used machining techniques in the world.
Today, industries continue to push the boundaries of what’s possible with centerless grinding, proving that a simple idea—born out of necessity—can shape the future of precision engineering.
Experience Precision Like Never Before
At Absolute Grinding & Manufacturing, we take pride in delivering high-quality, small-part precision grinding using time-tested methods. Whether you need precision grinding for cold heading or Swiss turning industries, our skilled craftsmen are ready to bring your vision to life.
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