"HOME" position on a CNC Mill, switch locations?

[Robin Hewitt]

Windows will not let you take over a timer interrupt, you can hook into a 1kHz system tick but that isn't fast enough. This came to a head when Windows could no longer guarantee to service a serial interrupt in time to stop an over-write with only one level of buffer, they needed 16.

[JAZZCNC]

Windows will not let you take over a timer interrupt,

Unless you take over windows.!!. . . . Tell Art fennerty it can't be done.! . . . . .The Boffin's said Mach3 could never be done but Hey presto.. .

[Dragonfly]

Yep, Mach3 own high priority driver takes care of that. I'm not sure it can work with Win7 and 8. Although I've read some people use it under Win7.
As for the coordinates of the machine, my personal opinion is that the near left corner relative to the operator's most convenient position should be assigned X0/Y0. It does not matter which axis is the longest one. Thus you maintain correspondence to the CAD and CAM software. Setting work zero is another thing and depends on where you fix the material on the table. For long machining sequences I zero the machine by means of home switches (Mach3) and then write down the real (machine) coordinates of the work zero. Just in case something goes wrong I am able to reposition with acceptable accuracy.