Steady rest with predictable micron-sized adjustment

A steady rest for gripping and finely positioning a workpiece, the steady rest comprising:

• a working cover plate with a slidingly removable block defining threaded apertures, the block being received in the working cover plate;
• a right-hand cover plate,
• a central plate disposed between the working and right-hand cover plates, the central plate being adapted to move slidably therebetween, the central plate having an upper and a lower cross-channel for engaging upper and lower gripping arms, the gripping arms being movable relative to the working and right-hand cover plates between a clamped position and a retracted position, the working cover plate having a rail recess and a pair of cavities that respectively receive upper and lower guide tracks;
• a tapered horizontal rail defined by flat surfaces situated in the rail recess that is adapted to cause displacement of the workpiece horizontally;
• a vertical rail with a mating flat face that abuts the horizontal rail and an opposing face with inclined sections that meet on opposing sides of a flat middle section, the vertical rail being adapted to move the workpiece vertically,
• the horizontal and vertical rails contacting the rail recess and each other while controlling location of the gripping arms, the horizontal and vertical rails being movable relative to each other within the rail recess under the influence respectively of a horizontal adjustment rod and a vertical adjustment rod that are received and rotatable in the apertures defined in the block to adjust a position relative to the working and right-hand cover plates at which the workpiece will be clamped when the upper and lower gripping arms are in the clamped position;
• wherein a 90 degree turn of the vertical adjustment rod displaces the workpiece vertically by 1 micron, or a 90 degree turn of the horizontal adjustment rod displaces the workpiece horizontally by 1 micron and securely repositions the gripped workpiece while holding the workpiece in place, despite forces exerted by machining operations and by a spinning mass of the workpiece so that the steady rest is configured to support and displace the workpiece predictably before and during machining.