It is generally not possible to make good Rockwell hardness measurements with a poorly operating machine. The initial consideration should be to use a Rockwell machine capable of measuring to the required accuracy and repeatability. As discussed previously, the errors in the operating components of the hardness machine should be identified and assessed through the direct verification process (see 5.1). Depending on the required level of accuracy, simply meeting the specified operating tolerances may not be adequate. Adjustments may be needed to bring each component to the center of tolerance. Unfortunately, for many types of Rockwell hardness machines, these types of adjustments are not possible in the field and, in many cases, may not be possible at all.
It is also important to use indenters that have been certified as meeting all of the requirements specified in the test method standards, including the shape and alignment. Until recently, obtaining certifications of the physical dimensions of diamond or ball indenters has been difficult. Once in use, indenters should be inspected frequently by visual means to help determine if damage has occurred.