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Free book download

Know Your Machine Tool, a book that helped machine tool metrologists, operators, and researchers measure and understand the capabilities of their machine tools, is now a free download from Lion Precision in the Technical Library portion of their website.

The 1991 book by Tim Sheridan was the first to show practical, step-by-step processes for measurements of spindle error motions according to the ANSI B89 standard (Axes of Rotation, Methods of Specifying and Testing). Spindle error motions on machine tools are responsible for errors in feature location, feature roundness and surface finish. In disk drives, spindle error motions limit data density.

The maximum speed of high-speed drills is limited in part by spindle error motions. Precision spindle and machine tool manufacturers and users now use these methods to test and characterise their machines in order to predict their behaviour and capabilities.

Lion Precision is the manufacturer of the Spindle Error Analyser software and high-performance capacitive sensors used around the world for machine tool measurements.

Know Your Machine Tool has been superseded by the new book, Precision Spindle Metrology by Eric Marsh Ph.D. which is available at or can be purchased from Lion Precision (

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