You need Capacitors for the switches when using some breakout boards like the CNC shield for arduino or else the switch may go of randomly. Place the capacitor as a bridge between the two leads, close to the break out board as possible.
100nF 0.1uF 104pF 50V Ceramic Disc Capacitors DIP top
Product Name : Ceramic Disc Capacitors
Capacitance : 104PF / 0.1uF
Voltage : 50V
Color : Brown
Weight : 82g
Package Content : 20 xCeramic Disc Capacitors