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Tool presetting – PoCo-Bush


The correct positioning of tools is very time-consuming when cutting or cold-forming threads with specifi ed start position.

The position-setting bush PoCo-Bush makes this an easy and accurate procedure. Thanks to the PoCo-Bush the angular position of tools relative to the index notch of HSK shanks can be determined in few steps with a presetting device. Afterwards the values of the presetting device can be entered directly into the machine control unit.

Together with the special collet holder for threading tools PoCo-Synchro the angle can be determined with an accuracy of smaller 5° and as a result the production of threads with specified start position is possible.


The PoCo-Bush is screwed onto a clamped tap or cold-forming tap using the attached ratchet until it reaches the end stop. This procedure ensures a screwing operation which reduces stress on the tools.

Afterwards the measuring cycle of the presetting device can be started. The angular position (C-axis) and length dimension (Z-axis) are determined by means of the axial and radial position balls. The marked corrected values are added to the angular position respectively to the length dimension (both included in the cycle) and result in the accurate setting values.

Then, both data (C-axis and Z-axis) must be entered in the tapping cycle of the machine control unit. Alternatively, it is possible to enter the angular position (C-axis) via the length correction value. A precondition for that is a synchronous tapping cycle which is started via the angular position.

And finally the angular position can be rechecked with the PoCoSys test systems on the production machine or on the 3D measuring machine.

Presetting device with automatic measuring, including rotation.


The accuracy depends on the following conditions:

  • Correct synchronisation of machine and control unit
  • Accurate machining of face side (e.g. contact face of spark plug)
  • Collet holder for threading tools PoCo-Synchro
  • Tap respectively cold-forming tap
  • Position-setting bush PoCo-Bush
  • Presetting device with automatic rotation (recommended)


EMUGE offers an extensive range of taps, cold-forming taps and thread milling cutters for the production of threads with specified starting position.