There's no place like home Re: G code

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "doug98105" <DougR@a...>
wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "ballendo" <ballendo@y...>
> wrote:
> > In CCED, "Fred Smith" <imserv@v...> wrote:
> > > Most controls do have a command for homing. On Fanuc it is

with

> > > G27, G28, and G29, each with it's own capability.

> I get the feeling that everyone who is participating in this thread
> is not talking about the same thing when they mention HOME.
>
> One of my machines has HOME, REFERENCE, and may have a part ZERO
> position. The HOME and part ZERO are user specified. REFERENCE
> position is determined by hardware. At various times I've seen all
> of these called HOME. So which are you guys talking about?

G28 is a return to machine reference position. REFERENCE on your
machine.

Many machines require that this be done manually at startup through
the operators panel. Some machines automate this process and will
step through the Axes Z-Y-X automatically. Usually no other motion,
programmed or manual, is allowed until this step is completed.
Several manufacturers call this homing and have a button (soft or
hard) with this word on it.

Any other position can then be defined as an offset from the machine
reference or home position. On lathes this is often called "safe
tool change position". Returns can go to this position to simplify
programming tool changes, but will NOT check that machine position
has been maintained.

Fred Smith - IMService