Tool turrets have previously been proposed including tool turrets which would carry both OD and ID turning tools. In U.S. Pat. No. 3,786,539 it was suggested to have a single slide carrying two separate turrets, one having OD tools and the other having ID tools, and since they were on the same slide, the two turrets could be used only alternatively. Also, the use of tools in one turret often meant that the tools in the other turret might interfere with other parts of the machine tool.
U.S. Pat. No. 946,924 suggested the use of a single turret which could hold both OD turning tools and ID turning tools at different longitudinal dimensions along the single turret.
U.S. Pat. No. Re. 29,694 suggested the use of a compound slide mounting a single turret which had two levels along the axis of the turret, with the first level carrying OD turning tools and the second level carrying ID turning tools. Only a single tool at a single level could be used at one time, and again it was often difficult to avoid having a tool at one level interfere with use of a tool at the other level.
U.S. Pat. No. 3,835,516 had a single turret mounted on a compound slide, and on the periphery of the turret there were mounting surfaces which would accommodate either OD or ID turning tools.
Another tool turret proposal was one which was generally a flat disc with OD turning tools mounted generally radially thereon and alternating with these OD tool mounts were ID tool mounting surfaces, with all tool mounting surfaces being uniformly spaced. A somewhat similar tool turret mechanism again was a generally disc-shaped turret with generally radially disposed OD tool mounting surfaces. At one section of the periphery, ID tool mounting surfaces alternated with the OD tool mounting surfaces and at another section of the periphery the OD tool mounting surfaces were adjacent to each other and at a slightly closer spacing than the OD tool mounting spaces in the first-mentioned section.