Look forward to the results from that.

You can see in my first post that the initial stiffness measurements were on the collet nut - DTI on the round part just above the flats and load applied next to it on the flats. So I did include the spindle in the measurement, but not the tool as that would depend on the tool used for each cut. You could argue the reference setup in many ways, but that's what I did. If you agree Jonathan, would you mind reading off the collet as described when you repeat? If Eddy has copied my method then we'll have 3 comparible results to get a sense of the range of stiffness vs performance vs design to add to the general knowledge on the forum.