Re: Learning BDI Emc - Outputs, Home position

["Dean L. Hedin" <dhedin-at-vsi.net>]

On my home brew 3-axis wood mill I took a different approach than most in 
this regard.

1) I arranged for the right handed coordinate system.
2) I ommitted the  (-) limit switches, I did put in the (+) limit switches
3) I edited emc.ini and set all the MIN_LIMITs to 0 and
    set the MAX_LIMITs just a little over the max extent travel
    for each axis on the machine.
4) I placed the home switches at x=0, y=0 , z=0!
5) I told it the homing direction was towards 0 for each axis.

My home/limit switches close a small amout away from the max extents
of the axis mechanisms, so a small amount of overtravel is accomodated.

I plan on cutting 3-d models on my machine, I want to avoid 
negative numbers in my code (unless it is some sort of relative move).

Of course the first thing I do is try out Deskam's Deskgrave and naturally
it only allows a negative Z "cutting depth"  Arrrgh!  Search and replace.
I guess most people think that z=0 is the top surface of the workpiece
and that is why they like "negative" z cuts into the surface.   

EMC seems to be happy with my arrangement.   If the interperter
see's any -x,-y,-z in the G-code it stops so I have'nt run into any
- limit out of bounds issue.  Plus I saved myself the hassle of wiring in an 
extra set of switches.