Diamonds are more than a girl’s best friend; they’re also a machinist’s best friend with diamond turning (a process that is oftentimes used to manufacture optical devices and systems). On principle, essentially almost any material can be turned on a diamond turning machine. But, as that’s based on principle, there always seems to be an exception to the rule.

Thankfully, from years of development and advancement, not only are multiple materials, such as plastics, metals, and infrared crystals, able to be turned on this machine tool, different approaches of turning are now the norm. People discovered besides woodturning, they could turn metal, among other materials. During these discoveries, discoveries on how to machine were also made — it no longer has to be completed solely by hand. Thus, with different approaches to diamond turning becoming more and more common, the accuracy of producing a mold inserts, optical systems, and other objects has increased. The four methods of diamond turning that are used to frequently produce articles include traditional turning, off-axis turning, fly cutting, and free-form machining.

Taking a cue from its name, traditional turning is the same process that’s been used for centuries. However, what’s used in the 21st century is amped up from ancient turning methods. Along with numerical control, computer numerical control (CNC) has become a method that automates the diamond turning (and other turning) process(es). Not only is traditional turning now a more streamlined, and less-time consuming, traditional turning combined with CNC creates a an article with an accurate shape.


   A  CNC turning center in the FAME Lab in the Leonhard Building at Penn State. (Photo: Nathaniel C. Sheetz/Wikimedia Commons)

Switching from one method that has been known for thousands of centuries to another, more contemporary approach to diamond turning, off-axis turning, is a method that doesn’t rely on symmetry; off-axis turning is the complete opposite, as it has the workpiece mounted asymmetrically to the spindle. When using this method, many turners transpose ‘off-axis turning’ with ‘off-center turning.’ Simply put, this approach to diamond turning means whatever article the turner is producing isn’t being turned on the rotational center, hence it relying on asymmetry. Depending on the specifics of machine tool used for off-axis turning, the turner has the ability to change the axis to be placed wherever the turner desires, creating repeating patterns or unique designs that have a rotational center — one, which doesn’t coincide with the center of the article.


  Off-center and off-axis turning, a complex zigzag finial. (Photo: Phil Holtan Woodturning)

Whether you’re in the turning business, or are new to the trade, there is more than one way to turn workpieces when it comes to diamond turning. Traditional turning, off-axis turning, and other methods in between can produce some ornate, distinct designs that will make you glad you chose the machine tool over diamond jewelry.



There is more to come about approaches to turning! Stay tuned to the Greenlight Optics blog in the upcoming months to learn more about fly cutting and free-form machining.