Re: G02 / G02 I and J arguments

Larry,

You've gottten a couple of answers to your question, but I want to
emphasize there is no simple single answer to your situation.

Generally, I&J can mean either the distance from arc start to arc
center (with various signing conventions) or I&J can represent the
actual coordinates of the arc center. Whatever I&J mean depends on
what the target CNC control defines them to mean. In other words,
before you can generate the Gcode correctly you have to know the
specs of the CNC controller that code will run on.

CAM programs handle this confusion by having post processors that
allow custom configuration of the Gcode generation for each flavor of
CNC controller. One CAM program I know of comes with more than 50
post processors, each defining the exact way the Gcode must be
generated for that particular controller. This is what makes life
interesting for CNC programmers.

The same confusion exists between CNC controllers over how many
degrees of arc a G02/G03 can execute in a single block. To be on the
safe side if you broke every arc into a series of 90 degree or less
segments you'd probably cover most all controllers.

Doug

--- In CAD_CAM_EDM_DRO@y..., "Larry Edington" <ledington@c...> wrote:
> Could someone explain to me how the I and J values are used on the
circular interpolation commands?
>
> I understand the G02 and G03 commands when using the R "Radius"
argument but haven't found a good example of the I and J calculations
necessary for arcs. I understand if you need to do a 360 degree
circle, in G code you have to split it up into a G02 and then a G03
command.
>
> I'm trying to convert an HPGL AA ( arc absolute ) command to it's G
code equivilent. AA gives you X and Y center along with the arc's
angle in degrees.
>
> thanks,
> Larry E.
>
>
>
> [Non-text portions of this message have been removed]