Re: Linux vs. DOS

I hooked up my home switches for the lathe and tried the function out. Over
all it works just as Jon described. HOMING_POLARITY controls the direction
the axis moves when you hit the home button and HOME_SWITCH_POLARITY takes
care of whether you switches are NO or NC.

I found that if you set the HOME_SWITCH_POLARITY wrong what happens is the
program functions just like it does with no home switches attached. Click
home and it zeros out the selected axis without any table movement.

The one thing I am disappointed in the home function is that the position of
the switch seems to always correspond to 0.00 for the axis. In looking real
quickly I didn't see a way to indicate home as being a different position.
From my limited home shop type experience this is a MAJOR pain for setting
up a switch for the Y axis (X in lathe terms) of a lathe. With a mill all
movements are relative and if you move your home point .100 other than
having to move your tooling you will still get parts that are the correct
dimension. On a lathe the 0.00 point on the Y (X) axis has to be dead on to
the centerline of rotation or you get off size parts. In DeskNC I was able
to tell the program what coordinate I wanted home to be. This way I didn't
have to try and adjust the position of the switch to get it so it clicked at
exactly 0.00. All I had to do was home up one and then take a cut on a
piece, measure it and enter 1/2 of the amount I was off as the coordinate
for the home switch.

Matt, any chance you can ask Fred if we can get the ability to set the
coordinate we want to be home in the ini file?


Tim
[Denver, CO]

> -----Original Message-----
> From: Jon Elson [mailto:jmelson@...]
> Sent: Sunday, June 06, 1999 6:17 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] Linux vs. DOS
>
>
> From: Jon Elson <jmelson@...>
>
>
>
> Dan Falck wrote:
>
> > From: Dan Falck <dfalck@...>
> >
> > Skimming through the documentation, I couldn't find this- how
> do you use
> > the home switches in the code? Maxnc uses a G61 switch sense
> command and
> > commercial CNCs use different proceedures.
> > What do you do to home the machine? My switches aren't hooked
> up yet, but I
> > would like to know before long.
>
> I don't have my home or limit switches hooked up, either. But, I
> went through
> this with Fred (or maybe Matt) some time ago, and think I understand it.
> The home switch must be set so it closes when the machine is between
> the limit switches. It makes sense to put the home switch near one of the
> limits, for the following reason. In the .ini file, you define
> which way each
> axis is to move to go home. So, you put the machine in a position on
> the 'right' side of the home switch manually, then hit the home
> button while
> that axis is highlighted (selected) on the screen. The machine moves in
> the direction specified in the .ini file until the home switch
> closes. It then
> advances slowly until the encoder index pulse is seen. The position
> marked by both the home switch being closed and the next index pulse
> is 'Home' for that axis. This puts it very close to the same place every
> time, probably within one or two encoder counts.
>
> Jon
>
>
> ------------------------------------------------------------------------
> Did you know each week we feature a ONElist story?
> http://www.onelist.com
> How has ONElist changed your life? Please share your story.
> ------------------------------------------------------------------------
> welcome to CAD_CAM_EDM_DRO@..., an unmodulated list for
> the discussion of shop built systems in the above catagories.
>