Just thought I'd share. I found it very informative.
This is good article on dual contact spindles/toolholders, but I am a little surprised that they did not mention the BIG-Plus system?
I have had experience of bell mouthing of spindle, when we first started fitting standard VMC like Bridgeports & Hurco’s with 10,000 rpm spindle.
If they had been running all day at max-revs, we found if the operator did not remove holder overnight, or the program left the tool in the spindle. As the spindle cool the toolholder shank was rung into spindle. So when operator started up the machine, and wanted to carry tool change it damage the ATC trying to remove the tool, and the only way we could only remove tool safety was by running the machine for a few hours.