Spindle twist on Tool Holder when tightening.

Hi

A physical behavior with the Tool at tightening on the Tool Holder.

The table is the Z-axis 0°. (Electronic bevel) and the Tool Holder's Z-axis is at 0° too on x and y axis. Perfect settings.

When I install the Tool, it's Z/x and Z/y becames 0°,okay.

Then, I tighten the Tool and I get a move of the tool on the Z/Y axis in the Tool Holder at the last moment of tightening. Result... 0.5° twisted tool.

This is really a problem to mill flat pocket or for surface finishing.

May I need to replace the Tool Holder ? Mine is twiste ?

Thanks for any help.
Manu

Here a link to a movie to see it https://1drv.ms/v/s!AiMQKzhNsuzMjLxsG0f4KG1TwbHJHw