i own a a retrofitted router with one stepper on y, one on z and two steppers on x (one is configured as axis a) .. 
stepper A is configured to mirror stepper x.
machine works perfectly, and have run it for 3 years with NO home switches. and never a problem with crashes (i am careful!) 
finally decided I need them to make my machine more reputable because I am doing some jobs over and over.. (to the point were I have Fixtures for the machine that I never saw in the beginning) 
anyhow. 
the machine has existing homing / limit swithes which are of the normally open type. 
using these existing switches I wired the switches in parallel.. configured my inputs for X home , y home, z home and a home. 
and tried homing
z works perfectly
y works perfectly
x however.. works half!
 one of my motors (we will call X, stops as it should) 
the A motor however continues to run. even after the switch has been activated. 
I have attempted to EMULATE the a axis home switch, 
I have tried to disable and enable and reverse the a axis.. 
but I am slowly tearing the machine apart during this home cycle..
can anyone think of a reason why my axis motor would continue to run forward after the limit switch on the x axis has been tripped.