Since the VDI shank is round it can not ensure the accurate positioning of the head on the turret during operation, when a significant radial force can be applied to the tool. A special VDI head Positioning Block has been designed to go around this problem.
Radial VDI live tooling normally has a so called Positioning Block shown on the picture. The axial heads with an offset also must be equipped with the Positioning Block
The big opening in the center can have U shape (as shown on the picture) or be round. The special positioning pin located on the VDI turret goes into this opening.
The positioning block can be made as a one piece with the main VDI head body or can be attached to it as a separate part (as shown on the picture). In this case the positioning block must be tightly screwed to the main VDI head body ensuring its steady positioning.
Please note four small screws adjacent to the opening in the block. Two of them marked on the picture as "Positioning Screw" are for the positioning of the head and the other two, marked as "Fixing Screw" are for the preventing of the unscrewing of the "Positioning Screws".
When setting up a VDI head on the turret, make sure the positioning pin will go into the opening in the positioning block. Release the Fixing Screws and release the Positioning Screws. Adjust the VDI head to the correct position, and fix the correct position using the Positioning Screws. Do not use only one positioning screw. Make sure both Positioning Screws are touching the positioning pin of the turret. Check the position of the head again to make sure it did not change. Adjust the position if necessary and fix it with the Positioning Screws. Screw in the Fixing Screws to secure the Positioning Screws.
• Download the "VDI Head Positioning Block" article (PDF).