Cool, will have to delve into that, with the sander it probably takes 2 or 3 minutes to get down to where the start switch clicks
Quick way to slow it would be an amp or more of DC through one of the stator coils - quite a few industrial lathes pre-VFD used DC braking, usually connected to back contacts on one of the motor contactors, with a timer to cut the DC after a suitable time. if the DC is left on, it'll eventually overheat the motor windings, but it slows quite quickly!
Dave H. (the other one)
For the sander that would work great, even if you used a push button to activate it.