Table mounted tool changer

Has anyone ever seen a table mounted tool changer on a mill?
I was thinking of designing one to hold 4 or six tools. The CNC
program would be written to position itself over the proper place and activate
the power drawbar. The holders would be placed at specific coodinates and each
tool cold be fetched at will. spring loaded stop prongs would keep the NBT-40
tooling from spinning during the change.

What is wrong with this idea? I seem to see very complex carrousel arangements
that bolt near the column. They also have complex retention mechanisms that
avoid threads and opt for buttons or nubs. I guess breaking the taper away is
a big issue.

I guess people want speed and flexibility in a MFG environment. An the table
mounted tool changer is far away and takes up table space.

dave