Re: G02 / G02 I and J arguments

Hi Art,

That sounds great! I played with HPGL some years ago, as output from my
old Cadvance (P-cad) package. All they generated were lines and cords.

How many variations of I,J style G02/G03 ARC's do you support? I'd only
seen Vector CAD/CAM generate the one type, because I just use the ISO
001 output. Is there another output to select to see other variations?
Just curious. the 'R' style ARC's are also something I wanted to
investigate.

I've heard that G12/G13 (?) are used for Helical Arc's. I would also
like to generate one in Vector CAD/CAM, and see if my MaxNC -PRO will
cut it (Gotta find/make a thread mill too)!

I didn't ketch who was using a G02 AND a G03 to draw a FULL circle.
Sounds like cutting that way would cause problems! Shouldn't it just be
a series of arcs in the SAME direction? By the way, my examples below
were TWO separate examples of ARCS, not meant to be used together!

Alan KM6VV


Art Fenerty wrote:

>
> 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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