a headrig slabbing head for machining a face on a log comprising a movable base platform mounted on rails to allow for varying the position of the base platform which supports a guide system having a carriage member adapted for movement along the guide system . a chipping head driven by a motor is mounted to the carriage member for cutting a face on a log . the position of the carriage member on the guide system can be varied to allow the chipping head to be adjusted to machine a face on logs of different diameters .