Involute interpolation error correction system

A method of correcting an error attributable to an involute interpolation with a numerical control device said method comprising:

• (a) obtaining in the numerical control device a curvature radius from a basic circle to a start point of a bite or leftover on a first involute curve and an error amount in a normal direction of the bite or leftover at an end point of the first involute curve, from an actual work shape created in accordance with a command for the first involute curve, when the work shape is liable to cause the bite or leftover;
• and
• (b) setting obtained values as parameters in the numerical control device and performing machining, with the numerical control device, based on an interpolation such that the first involute curve is divided between second and third involute curves, the second involute curve having an end point on the start point of the bite or leftover, and the third involute curve having a start point on the start point of the bite or leftover and having an end point deviated from the end point of the first involute curve by the error amount in the normal direction.