Abstract: A jig for holding a core which comprises a movable platform, a base positioned on the movable platform which has a receiving hole, and an inserter positioned inside the receiving hole of the base, shaped corresponding to the shape of the receiving hole, to fasten the core to the inserter. The inserter comprises a core receiving hole, a plurality of positioning recesses disposed symmetrically in the periphery of the core receiving hole, a plurality of positioning blocks received in the positioning recesses, and a plurality of resilient elements received in a space between the positioning recesses and the positioning blocks to hold the core firmly.

Abstract: A numerical control device includes a substrate, an adjusting unit, a machine tool, a workpiece holder, a distance measuring component and a control unit. The adjusting unit is movably positioned on the substrate. The machine tool is positioned on one side of the adjusting unit and has a distal end. The workpiece holder is positioned on the substrate and faces the machine tool. The distance measuring component is aligned with the machine tool and the workpiece holder. The control unit is electrically coupled to the distance measuring component and the adjusting unit.

Abstract: A jig for holding a core which comprises a movable platform, a base positioned on the movable platform which has a receiving hole, and an inserter positioned inside the receiving hole of the base, shaped corresponding to the shape of the receiving hole, to fasten the core to the inserter. The inserter comprises a core receiving hole, a plurality of positioning recesses disposed symmetrically in the periphery of the core receiving hole, a plurality of positioning blocks received in the positioning recesses, and a plurality of resilient elements received in a space between the positioning recesses and the positioning blocks to hold the core firmly.