Just wondering what everyone recommends for Quality Limit and Homing Switches, there will be flood coolant involved . So I Guess an IP67 rating will be required.
I was thinking roller type snap action , that way during a runaway it wouldn't peel them off the machine! going to need atleast 6.

I use slow acting limit switches from Automation Direct (part #AEM2G43X11-3).  I tried snap action switches but had repeatability issues.  Tried the slow action style and they repeat quite well.

 Thank You for the Reply , I was curious as to the repeatability as home switches for Mach 4

My mill is a PM-932 converted to CNC.  On startup I home the machine, run a warm up routine, then run the homing routine again.  It repeats within .001" to .002".   

Hi,
I used these for home switches, they have proven to be very repeatable, about 0.05mm variance between sessions.

http://nz.element14.com/omron-industrial-automation/z-15gq22-b/micro-sw-roller-plunger-spdt-15a/dp/1500340

Craig

We have used both types of home switches that Tom and Craig have used.  While the ones Craig uses is more repeatable, we have those types of switches on our Fadal, they are constantly covered in chips and have to be cleaned off before each reference cycle.  Although we use the plunger instead of the lever switches from Automation Direct (AEM2G12Z11-3), they are a better option if it is going to be covered in chips and coolant since all the connections are enclosed and sealed inside the switch. 

The best repeatabilty for slow make slow break switches will be using a normally closed contact that you open for location indication. When a contact is landed its position is exactly known. Pushing it open can be extremely precise.

   The repeatability factor for homing this beast has to be with in .0001 tenths , I will eventually use the machine as a powersport block and head machine center . So should I use NO/ or NC/ . Snap or Slow ? Roller Lever or Roller plunger style .
I like both of the AD switches for the IP67. I will use the switches for both Homing and Over Travel . I will mount them under the massive table to help protect them . Will all so use 2
on the Z , to help with tool changer set up .

The way industrial machines normally get precision homing is to use a two factor
system that consists of a mechanical sensor for coarse, and an index pulse from
the encoders on the servo motors as the fine position. The coarse gets you to
within a half a revolution of the motor, then the system backs up to find the
next instance of the encoder index signal.

 That's what I have with my machine Steve , But the old fadal was strickly software limits . The old Numatix control used the scales for homing the machine cords.
Then the motor encoder for position and velocity feedback. Was a tricky deal. It would over travel and break hell out of everthing!
 I want to combine the Switches for Home and Limit Switches for Safety . Just want a good quality accurate outcome.