Machine control system

A feedback apparatus in combination with a programmable machine controller for a multi-spindle machine having a plurality of spindles each producing a part thereon wherein the controller provides electrical output signals that control the position of at least one machine tool used to form machined parts on said spindles, said machine tool having a position, the feedback apparatus comprising:

• a measuring device that provides an electrical output signal that is indicative of a characteristic of each machine part which characteristic is related to the position of the corresponding machine tool,
• a data analyzer for receiving said measuring device outputs and calculating an average value and range for said characteristic among a first subgroup of said part, said first group comprising a predetermined number of said parts made on each spindle of the machine, said data analyzer providing electrical output signal indicating average value and range of said characteristic of said parts in said first subgroup, and
• a programmable offset device that receives said output signals from said data analyzer and instructs the controller to offset the machine tool position responsive to said output signals from said data analyzer, whereby said average value and range are maintained within predetermined limits, said programmable offset device including a setup subroutine that is initiated when said range exceeds a predetermined limit or when said characteristic of any said parts is outside predetermined control limits, wherein said setup subroutine calculates an average value of said characteristic for a predetermined plurality of said parts from each spindle and instructs said machine controller to offset said corresponding machine tool position responsive to said average value calculated for each respective spindle.