Complex sentence: A tailstock is a device often used as part of an engineering lathe or wood-turning lathe with a rotary table on a milling machine to apply support to the longitudinal rotary axis of a workpiece being machined.
Split into simpler sentences: A tailstock is a device often used as part of an engineering lathe, wood-turning lathe, or used in conjunction with a rotary table on a milling machine. Usually used to apply support to the longitudinal rotary axis of a workpiece being machined.