This invention relates to cutting tools used to machine materials to produce new surfaces and chips of removed material. Embodiments of this invention allow round rotating cutting inserts to be used in a more economical way, with improved accuracy, with improved sealing, and with greater ease of use. The rotary support device and cutting inserts may be used in either radial or tangential mounting types of cutters. It also provides a built-in, fully sealed means of fine adjustment of the cutting insert that is useful in some applications.