US Patent 7231703 Deburring method and automotive knuckle

A knuckle 1 has a through hole 3 provided in a fitting hole 4 thereof. A cutting tool 9, which has a diameter being larger than that of the through hole 3 and also has a cutting part having a hemispherical leading end portion, is caused to go into the through hole 3 at an angle at which the tool 9 does not touch the remaining part of the knuckle 1. Then, a burr formed at a fitting-hole-side open end portion 7 of the through hole 3 is removed by rotating the cutting tool 9 while the leading end portion thereof is made to obliquely abut against the open end portion 7 of the through hole 3.