Re: [CAD_CAM_EDM_DRO] Re: G02 / G02 I and J arguments

Alan:

Master5 can also import HPGL including ARC commands and will output the
G-Code equivalent.

Art

----- Original Message -----
From: "Alan Marconett KM6VV" <KM6VV@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, February 20, 2001 2:56 PM
Subject: [CAD_CAM_EDM_DRO] Re: G02 / G02 I and J arguments


> Hi Larry,
>
> Think of the I and J as offsets BACK TO the center! I think Ballendo
> posted some good descriptions of G02/G03 some time ago. I use Vector
> CAD/CAM to generate Gcode, and as a tool to learn EXACTLY how these arcs
> work. You can eval Vector (and BobCad), and learn a LOT that way!
>
> This command draws an arc clockwise from 67.5 deg. to 315 deg. First we
> move to the start of the arc (G00), then we cut TO the X,Y of the G02
> command. In the arc command, I denotes the X offset to the CENTER of
> the arc, and J denotes the Y offset.
>
> N1000 (#3 CW 67.5 -> 315)
> N1005 G00 X 0.1913 Y 0.4619
> N1010 G02 X 0.3536 Y -0.3536 I -0.1913 J -0.4619
>
> I'm told that most newer controllers CAN handle full circles.
>
> N1100 (#1 CCW 360 circle @ 67.5)
> N1110 G00 X 0.191 Y 0.462
> N1120 G03 X 0.191 Y 0.462 I -0.191 J -0.462
>
> Notice that the G03 X,Y destination is the SAME as the place the arc
> started!
>
> Sounds like you're writing an HPGL to Gcode program! Could be useful!
> The early CAD programs I was getting HPGL output from only used the
> minimal commands. ARC's were drawn by a set of cords.
>
> I don't care much for the 'R' variation of the command. It can't do
> large arcs!
>
> Hope this helps a little. I'd like to hear more about your program.
> Contact me off line if you wish.
>
> Alan KM6VV
>
>
> Larry Edington 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.
>
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