A core puller device for a block machine, a block machine with such a device as well as a method for the preparation of shaped stones in which at least one core puller arranged on the sliding facility of the core puller device is temporarily inserted into a stone mould of the block machine and retracted after a packing operation in the block machine are provided. Here, the core puller device is constructed or the method is configured such that the operative connection between the at least one core puller and the sliding facility of the core puller device is temporarily neutralized.