A control apparatus for machine tools is provided which comprises a pulsed digital difference detector having one input connected to a digital branch and having a second input connected to a follower drive and having an output, an adding register having its input connected to the output of the pulsed digital difference detector, an analog nominal value source having its control input connected to the output of the adding register, and an analog branch having an input connected to the analog nominal value source and having its output connected to the input of the follower drive. A drive motor for the tool provides a signal to the digital branch and a drive motor for the blank forms part of the follower drive. The drive motor for the tool is a d.c. motor coupled to a velocity pickup, and cooperating with means for withdrawing the tool and a distance pickup coupled to the drive motor for the blank.