Re: [CAD_CAM_EDM_DRO] setting machine zero

andrewyslee wrote:

>Hi,
>
>I am trying to configure sherline and flashcut to something that can
>simulate their bigger brothers (learning purpose, trying to program
>like for big machines). I understand most cnc router have their
>machine zero at the maximum +X +Y and +Z (max. right, max. forward,
>max. top)
>
>

Approaching this from the Router Level, Those companies you speak of do
not really use a "max X or Y+ position as the Zero,Zero Point as you
might be describing. Rather, that IS their Zero point in X and Y. From
what I think is your view point, Imagine for a moment putting the stock
into that corner "upside-down". Now running any conventional toolpath
with a bottom left 0,0 location, runs just fine.

For years I could not understand why companys were doing this. The
Upper far right corner as you described for x-y "0", especially on large
moving gantrys machines can be more difficult to fit into the job
ergonomically. For some machines like those using the Extratech
controler, The machines "home routine" has usually been assigned to the
far lower left (topview) after running a job and in many cases WAS the
location it automatically moves to to locate "machine zero" via switches
even though it knows machine zero is in the upper right (topview)! New
hermes engravers did something similar... The Home routine to look for
switches was towards the top left ( top view), but machine Zero when you
ran a toopath really was from the lower left !

Under the design of using anything but the bottom left corner, one is
forced to make sure the machine has moved there after a job so you can
see your work or remove the material. Some times this "run to the
opposite end of the machine for home" routine was built into the control
and you could do nothing about it. And unfortunately on big machines,
when setting an alternate X-Y zero based on your material, one must jog
the machine all the way out to that far point to set it from that "home"
location. This takes more time than necessary....

I've seen most of these machines dictate the operators location ( by
location of a programming head or display) parallel to the Y axis on the
real "0" end. This method always made you visualize your stock and
subsequent toolpath as "X+" extending away from you and Y+ to your
left.I did not like the technique at all and changed the machines I had
to make more sense. I wanted the typical Cad programs "Bottom Left 0,0"
to be the same as when I stand in front of a machine. This Especially is
important when you train in others to run that machine. If the axis
"match" per say, they can understand it better.

If however some like the top right "0" scenario beneficial (your lower
right on some Multicam), I have found "Left and closest to you" as Zero
concept far more beneficial. The machine is loaded from the "front"....
One only has to jog a short distance to the corner of the materials 0,0
location.... You seldom need access to the machine for daily work from
more than 2 sides ( front and right) and It makes perfect sense in
relationship to any normal toolpath or drawing.

Everyone in the shops I worked in agreed to move zero to the lower left
on all machinery as from the location the operator stood to operate it.

>So with flashcut 2.0, In the machine configuration, I set max x-axis
>lenght to 9, max. y to 5 and max z to 6. Starting from program zero,
>I point move to X=+9, Y=+5, Z=+6. At this point, I zero the machine
>coordinates. The software draws a blue box showing the limits for z
>at -6, which will be just like their big brothers, the the blue box
>for xy plane extend from (9,5) to (18,10) which means that if I
>attempt to move to say x=1, this will be an illegal move as it will
>be out of the machine envelope.
>

You are correct with the scenario because your "move" of 1" is in the
"positive" direction of which there is no room to go farther ! If you
did an X= Minus1.0" move, it would work. This should indicate that what
you are trying to play with can be done, *but your drawing and your
toolpaths in effect need to have a zero point at that 9" and 5" max
point, and the toolpaths indicating the work that is happening is in
"negative quadrants".

If your Cam proggy can configure your toolpath code to do so, I can work
fine, but I'm not sure why one would want to.

>
>Is it that for flashcut, the only way to set machine zero is to set
>it at min. x (extreme left), min. y (nearest operator), max z?
>

To my knowledge yes. You can place your Part zero anywhere though. This
allows you to develop toolpaths based on a specific location and set it
accordingly at the machine. This way if your toolpath calls for work in
all 4 quadrants, it can do it fine as long as there is enough machine
"envelope" to do so. In your case above, "envelope" is what you ran out
of trying to make that additional 1" move. So, the "big Boys" do not
*really* do what you were trying, unless there is some really wierd
reason they need to, or if a boss who knows no different tells you
"that's the way way always did it and it works fine".......

That was easy, right ?

Chris L