Don Foreman wrote:
I'd suggest contriving a foot-actuated brake that can kill power and
stop the spindle instantly. ...

I don't know if you're talking about a mechanical brake, but you can
brake ac motors electrically. I've not done it, but if I recall
correctly, it's a matter of applying dc to the field winding. I'd think
that the only problem would be with how much current to apply.

Bob