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GH-Z/E – The stable counterboring and back spot facing tool.

Rigid spotfacing and countersinking, front and back in One Operation.

The GH-Z/E tool is a twin bladed front and back counterbore tool that produces accurate back spotfaces, large countersinks and precision forms. The two blades of the tool are radially extended and retracted by forced action when the direction of rotation of the spindle is reversed. GH-Z/E is especially distinguished by its high stability and rigidity.


  • Automatic front and back or only back spotfacing and countersinking without turning the work piece, optimal solution for CNC operation. 
  • Extremely stable and rugged tool system especially designed for machining large work pieces in heavy manufacturing applications and producing large countersink diameters. 
  • Exchangeable carbide blades with cutting geometries and material-specific coatings. 
  • Optimal design to suit specific customer requirements. 
  • Inner coolant supply behind the work piece directly onto the blade.


Countersinking is carried out from the same side as previous boring. On the basis of a change in the direction of rotation of the spindle, the blades are automatically radially retracted into or extended from the blade housing. The blades are retracted with left-hand rotation of the spindle. They are extended with right-hand rotation of the spindle. Two bolts which are eccentrically positioned in the blade control engage in a groove in the two blades. As soon as the blade control starts rotating, the blades – which are held in the blade housing so that they can move – are radially retracted or extended. The blade control is connected to the shank and is thus directly driven by the spindle. A driver system inside the control housing allows relative rotation of approx. 180° between the blade control and the blade housing. A torque bracket prevents rotation of the control housing. When the spindle is started for right-hand rotation, the blade control will first rotate and cause the blades to be extended. As soon as the blades have been completely extended, the spindle RPM are transmitted to the blade housing. The blade housing and the blades now start a right-hand rotation with the spindle RPM and are ready for machining. When the spindle is switched to left-hand rotation, the reverse process is initiated. The blades and blade housing stop. The blade control performs a left-hand rotation and controls the two blades. As soon as the blades have been completely retracted into the blade housing, the spindle RPM are again transmitted to the blade housing. The blade housing and the blades now perform a left-hand rotation.


  1. Anti rotation device 
  2. Shank 
  3. Tool head 
  4. Blade housing 
  5. Blade control 
  6. Blade/cartridge with insert

Product range

The GH-Z/E tool head is available in different design versions. The selection of the tool head is essentially determined by the bore diameter. Each tool is individually specified and produced for each particular application.