A cutting head assembly for use in cutting plate glass has a simplified drive train, all positioned about the vertical rotational centerline. The drive train includes a hollow bore drive motor having a drive adaptor directly engaged with a spline shaft that extends through the hollow bore. The lower end of the spline shaft is directly engaged with a cutting tool holder for retaining a cutting tool. The drive motor imparts rotational movement to the cutting tool through the spline shaft and the cylinder imparts vertical movement to the cutting tool by vertical movement of the spline shaft.