Above is the electrical solution I used for the limit switches. The 330 ohm resistors are not an option as they are needed to pull the voltage up to 5vdc after the limit switches are added. Note that even though the limit switches are normally open they offer enough resistance to drop the voltage on the Arduino to about 4.87. The pull up resistors ensures a 5 volt TTl logic until the limit switch is grounded out. One important note: do not connect the ground for the limit switches to pin 14 as shown in GREEN in the photo, use the ground on the opposite side of the Arduino located next to the +5 pin.
In the above photo you can see a small board I added to my CNC control box. The board has the three 330 ohm resistors mounted (sorry the resistors are not visible this photo). The small board has 4 connections; one connects to + 5vdc on the Arduino and the other three connect to pins 9,10 and 11. You should also notice that these pins have two wires connected, one wire goes to the arduino as mentioned and the other wire goes out to the NORMALLY OPEN limit switch.
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