Boring bar attachment for engine lathes

In a boring bar attachment for cutting accurate internal diameter or taper long and large diameter cylinders on an engine lathe, the lathe having a carriage frame, a chuck to which one end of the cylinder is rotatably mounted about a given center axis, and means to rotate the chuck, the improvement in the boring bar for attachment to the lathe, comprising:

• a support bar, longer than the cylinder and positioned inside thereof, the bar having a first end and a second end, the first end having chuck support means non-rotatably attached to the chuck, the second end having an assembly supported upon the carriage beyond the other end of the cylinder,
• a lead screw rotatably supported to and extending from the first to the second end parallel to the axis of the support bar, and variable power means supported at the second end to rotate the lead screw at a desired speed,
• a travelling block assembly supported upon the support bar for longitudinal movement thereon, a threaded opening in the block to receive the lead screw and thus slide the block for travel from the second end to the first when the lead screw is rotated in one direction and vice versa when the lead screw is rotated in a reverse direction,
• the travelling block assembly including a cross-slide supported upon the travelling block for movement transverse to the support bar, means to support a cutting tool at one end of the cross-slide adjacent the internal diameter of the cylinder, and means to accurately move the cross-slide to a position, relative to the internal diameter of the cylinder, to create the desired internal diameter or taper.