Re: setting machine zero

CL <datac@l...> wrote:

> 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

Thanks Chris,

I have no hand-on industrial experience. The only "industrial
experience" I have is reading Mike Lynch's notes and reading CCED
posts.

I agree that setting machine zero at bottom left is easier
mathematically and logically. It is good to hear that there are "big
boys" who set their machine zero at extreme lower left. However, for
the sherline, the easiest point to put limit/"home" switches is to
bolt it onto the motors, which means the switches (zero's) will be at
extreme top far right. I believe you have a Sherline. How do you
place your switches? If I leave the switches at the motors, I
wouldn't be able to use the flashcut method of setting the machine
envelope.

> 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