I agree with jahn normally closed switches are safer
the odds are greater that a cable will go open circuit due to repeated flexing
while it is possible for a cable thats been crushed to be short circuited
which limit / home switches are you using ?
if its this -
Attachment 372918
for each axis , its easy to wire 2 normally closed switches in series to act as the home and limit switches
with this switch with the LED indicator
Attachment 372920
it will be easier to wire one switch to one input !
with 4 inputs on the TB6560 board and 5 on the breakout board
you wiil only use 8 of the possible 9 inputs - 6 for each end of the three axis + E-stop + probe
john