Device for correcting mechanical errors in NC machine

A device for correcting mechanical errors in an NC machine, by which an incremental amount of movement of a control shaft is corrected based on an amount of correction of mechanical errors of said machine, and a corrected value is transmitted to a servo control section, said device comprising:

• means for adjusting the incremental amount of movement of the control shaft calculated during each of a plurality of samplings by a speed adjustment value;
• means for calculating a position command value by progressively adding a value of said incremental amount of movement subjected to said speed adjustment value;
• means for obtaining a position command correction value by adding a predetermined amount of correction for mechanical error to said position command value calculated by said calculating means;
• and
• means for calculating a corrected incremental amount of movement by subtracting a previously calculated position command correction value from a currently calculated position command correction value, both calculated by said calculating means, and means for transmitting said corrected incremental amount of movement to said servo control section.