Setting Z height with an ER32 collet

An idea came to me :eek:

Preserving the Z co-ordinate when changing tool by G Code alone :naughty:

1: Have the tool present itself in front of the job at tool change for easy access.

2: Put the new tool in less than tight and sticking out a tadge too far.

3: Move it over the metal then dip it slowly to Z0.0 so that the tool sets itself.

4: Lift, tighten, carry on.

Question is, how far does the tool move between "less than tight" and "tight", I need to get my DTI out methinks.
What do you lot reckon? :beer: