A rim drilling and milling machine has a base (10), a column (20), a turret (30), a saddle (40), a table (50), and a fixture unit (60). The fixture unit (60) has a foundation (61) and four clamping seats defined as two first clamping seats (63A) and two second clamping seats (63B). The first clamping seats (63A) are slidably mounted on the foundation (61) along a first radial direction, and are disposed at positions diametrically opposite in the first radial direction. The second clamping seats (63B) are slidably mounted on the foundation (61) along a second radial direction perpendicular to the first radial direction, and are disposed at positions diametrically opposite in the second radial direction. The four clamping seats can clamp at four equiangular points of a wheel rim.

A compensation chuck for centrically clamping workpieces includes a housing, two pairs of mutually diametrally opposite base jaws for receiving corresponding clamping jaws, and a drive unit which is moveable preferably by power clamping having two pairs of drivable entrainment members. Two adjacent entrainment members are respectively coupled together by a first rocker and two further adjacent entrainment members are coupled together by a second rocker. There is also provided a coupling ring which guides a first entrainment member and a diametrally opposite second entrainment member in the peripheral direction tangentially relative to the clamping axis, such that a motion play is provided between the entrainment members and the coupling ring in the radial direction.

A compensation chuck for centrically clamping workpieces includes a housing, two pairs of mutually diametrally opposite base jaws for receiving corresponding clamping jaws, and a drive unit which is moveable preferably by power clamping having two pairs of drivable entrainment members. Two adjacent entrainment members are respectively coupled together by a first rocker and two further adjacent entrainment members are coupled together by a second rocker. There is also provided a coupling ring which guides a first entrainment member and a diametrally opposite second entrainment member in the peripheral direction tangentially relative to the clamping axis, such that a motion play is provided between the entrainment members and the coupling ring in the radial direction.