Re: [CAD_CAM_EDM_DRO] New question about limit and home switches

johnhe wrote:

> > If I understand correctly, you are asking what happens if you drive
> > over a home switch while running a program, subsequent to homing
> > the machine. The answer is nothing - the home switch only gets
> > looked at during homing. Running over a limit switch on the other
> > hand will shut the machine down.
>
> I'm not sure I understand the need for them in CNC. On the mill I used in
> school we have a cursor keypad on the control to position the spindle

The reason for home switches is to be able to return to a precise position
after the machine has been turned off and back on (or when the program
needs to be restarted for some reason). EMC saves the offset between
ome and the work coordinate system(s), so they can be returned to the
same amount the next day. This is real useful if you are using the same
setup several days in a row, and don't want to have to carefully reset
your zero every time. Some people always set the corner of the
fixed vise jaw as (0,0), and this way, they don't have to use the edge
finder unless the vise has been removed.

Jon