Which Type of Limit Switch

[irving2008]

If you use a proximity switch such as the LJ12A3-4-Z/BX, you will need a supply voltage of 6 to 36v. anything below 10v won't work reliably (I found to my cost). The advantage of this proximity switch is that it is a sealed unit, you just need to keep swarf away from the sensor end.

Which is tricky on a mill, also the mill itself is a big chunk of iron so mounting proximity switches so they're not affected isn't so easy. Optical sensors as shown in the link on Eddie's post in suitably sealed boxes are a neater solution. A suitable sensor is this one: http://uk.farnell.com/omron-electron...ive/dp/1348961