re:Crashing CNCs: what gives ?

>Though I've seen it attempted many times I've never seen an operator
>actuated E-stop that really saves tooling. Generally things happen to
>fast especially with machines running production code, so man in the
>loop protection is not a good idea.

My late, younger brother, used to teach CNC machining for GM Tool and Die
plants. He had this idea of a pucker switch. It was a switch that would
fit in the chair of the operator. When the operator sensed an imminent
crash, the switch could detect the contractions of the muscles in the upper
legs, lower back and all in between. He figured that the switch could
give up to a full 1 second advantage to the time required for the operator
to sense a problem, his lungs develop the air to scream "Oh S#@t, and then
leap for the EPO switch.

I have now gone into CNC machining and my track record for needing the
pucker switch is about 60 percent. Having seen what can go wrong with a
1/4" end mill, the thought of the same going wrong with a 6" fly cutter
leads me to believe there is a real need for the DPS ( Dennis Pucker
Switch). Any of you electronic gurus up to the challenge??

Don