A machining apparatus has a vertical support frame defining two machining stations spaced apart in a direction, holders in the stations for rotating respective workpieces each about a respective station axis, and a transfer device for loading rough workpieces into the holders and for taking finished workpieces out of the holders. A single machining tool can be shifted in the direction between one position engaging the workpiece in one of the stations and out of engagement with the workpiece in the other of the stations and another position engaging the workpiece in the other station and out of engagement with the workpiece in the one station.