Relative to RPM readout and triggering to start a thread path:
Index debounce will affect the sensitivity of the index signal. IT basically is how many interrupt periods the signal must be present, or not present before a change is actually sensed in that line. SO if set to 2 for example, when the index appears it will be ignored for 2 periods to make sure it isnt noise. Same with when it disappears. Setting debounce too high will make the index go away altogether.
Since the length of the index is dependent on spindle speed, minimum length is variable, but the time must be at least 1 period at a debounce of zero. SO in 25000, thats 40us.
If a person notices a dropoff in RPM at a certain speed, they need usually a lower index debounce. Index inputs from an encoder are usually pretty short and will limit speed readings at some point as you go higher.
If you have the debounce setting too high the axis will just sit there waiting to confirm the rpm
before the start of a thread path.
Don't have specifics relative to switches .
RICH