Re: G92-program zero

["Joel Jacobs" <jj-at-netexp.net>]

Hi Darrell,
I may try that if all else fails - I'm reluctant because homing is meant to
set 'machine zero' and the software limits are relative to that position so
if I re-home to set 'program zero', the software limits will move too.
   I remember reading somewhere that EMC takes up half the backlash the
first move after the home and the full backlash on each direction change
thereafter so If I manually jog to where I want my program zero, the
backlash will already be taken out in one direction and if I use 'home', it
would immediately acquire a position error equal to 1/2 the backlash.
  Also EMC has a homing bug that makes it un-reliable with my setup.  I
mentioned it a few times on the list and was able to demonstrate it to Matt
at NAMES so I hope someone is working on it.
  I'm keeping my fingers crossed that the '%' at the beginning and end of
the program that Will suggested will solve the problem.  I will try it
tonight for sure.

Joel

----- Original Message -----
From: "Darrell" <dgehlsen-at-earthlink.net>
To: "Multiple recipients of list" <emc-at-nist.gov>
Sent: Monday, June 04, 2001 12:59 PM
Subject: Re: G92-program zero


>
> It sounds like you would be better off dialing in your zero and then
"Homing"
> that position. The problem with the way you are now doing it is that you
do not
> have a known "Home" or zero point.
> Darrell
>
> ----- Original Message -----
> From: "Joel Jacobs" <jj-at-netexp.net>
> To: "Multiple recipients of list" <emc-at-nist.gov>
> Sent: Monday, June 04, 2001 9:25 AM
> Subject: Re: G92-program zero
>
>
> >
> > Neither,  I am not doing any G92 commands in the program itself.  I am
> > manually jogging the machine to my program zero position - the corner of
the
> > fixture or the vice or whatever - then I go to MDI mode and type
G92X0Y0Z0
> > and the coordinates displayed all change to zero.  Then I run the
program.
> > When the program finishes it destroys my carefully acquired zero point.
> >
> > Joel
> >
> > ----- Original Message -----
> > From: "Darrell" <dgehlsen-at-earthlink.net>
> > To: "Multiple recipients of list" <emc-at-nist.gov>
> > Sent: Monday, June 04, 2001 11:59 AM
> > Subject: Re: G92-program zero
> >
> >
> > >
> > > Dave,
> > > Are you dialing in a start position and then in the program using a
G92 to
> > set
> > > part zero with out any X/Y/Z moves? Or are you dialing in a known
> > position,
> > > setting that as "Machine Zero" then in the program moving to X/Y/Z
> > position and
> > > then doing G92?
> > > If you are doing it the first way, you have no reference to a known
zero
> > so when
> > > you end the program you loose your zero because the machine goes to
your
> > unknown
> > > zero point.
> > > Use known points such as a home position and a corner of the fixture
or
> > vise and
> > > you will not loose your zero.
> > > Darrell
> > >
> > > Subject: Re: G92-program zero
> > >
> > >
> > > >
> > > > Hi Dave,
> > > > I may have to try xemc, I've been using Tkemc.  It never occurred to
me
> > to
> > > > try a different GUI.  What I've found though is that if I set G92 in
MDI
> > > > mode and stay in MDI mode I can abort any commanded move without
> > affecting
> > > > the G92 setting.  If I abort a running program the coordinate
displays
> > are
> > > > still correct but zero isn't zero any more - I can go to MDI and
enter
> > G1X0
> > > > and it will move and it will stop but not at zero - the x coordinate
> > display
> > > > will be non zero.
> > > >    If I let the program end, as soon as it hits the M30 it looses
the
> > G92
> > > > setting and the coordinate displays shift - I can go to MDI and type
> > G1X0
> > > > and it will go to zero and display zero but it's not the zero I set
with
> > > > G92.
> > > >   Sometimes I want to run two different programs on the same part
> > without
> > > > disturbing the setup or program zero and I can't do it.
> > > >   I didn't think anything should change a G92 setting except another
> > G92 -
> > > > G92.1 - G92.2.
> > > >
> > > > Joel
> > > >
> > > > ----- Original Message -----
> > > > From: "dave engvall" <dengvall-at-elltel.net>
> > > > To: "Multiple recipients of list" <emc-at-nist.gov>
> > > > Sent: Monday, June 04, 2001 1:08 AM
> > > > Subject: Re: G92-program zero
> > > >
> > > >
> > > > >
> > > > > Hi Joel,
> > > > > I've  done all sorts of things to shut down a program under xemc.
> > Switch
> > > > modes
> > > > > i.e. F3 or F5 will halt the program.  Abort. etc. I use M2 to end
and
> > > > being a
> > > > > non-expert it never occured to me to use M30.
> > > > > In fact, I'm not aware of ever doing anything that shifts what is
set
> > by
> > > > G92.
> > > > > Maybe I just don't do anything fancy.
> > > > > Hope this works for you.
> > > > >
> > > > > Dave
> > > > >
> > > > > Joel Jacobs wrote:
> > > > >
> > > > > > Could someone please explain to me how to stop a running program
or
> > even
> > > > > > re-run a program without trashing program zero?  I set program
zero
> > with
> > > > g92
> > > > > > before running the program.  If I abort the program or if the
> > program
> > > > > > exicutes M30 (program end and rewind) my program zero gets
trashed.
> > > > This is
> > > > > > really frustrating as I have to tear everything down and start
over
> > with
> > > > the
> > > > > > test indicator etc to find zero again.  Please help...
> > > > > >
> > > > > > Thanks
> > > > > > Joel
> > > > >
> > > > >
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>