CONCENTRIC devices for hob manufacturing Hobs are clamped manually on a CONCENTRIC ® mandrel and located between centers in various machines. This system is used during hob manufacturing, during grinding, relief-grinding, sharpening, and inspection. The hob is clamped with high precision and without backlash. The clamping mandrel is clamped on the shaft in a chuck and supported via the tailstock centre. Run-out accuracy: 0.003 mm.