Re: Re: How does G02 & G03 work?

Jon,
g00 g90 x-2.0 y0.0
g01 x-.5
g02 x0.0 y-.5 I-.5 J-.5
y-2.0
On a FANUC or AHHA control makes two lines with a 90 deg tangent arc.
Substitute
g02 x0.0 y-.5 I.5 J.5
and the arc starts at the end of the x move at a 90 degree angle going up
and around clockwise and ends at the beginning of the y move which is again
at a 90 degree angle.
Draw it out and you will see what I am talking about. Both g02 lines are
valid clockwise moves on either FANUC or AHHA and I thought FANUC was as
close to a standard as I could find.
Bridgeport and Allen Bradley both use the unsigned version but unfortunately
both are obsolete.
What code would you use if you wanted the second shape?
Darrell

----- Original Message -----
From: Jon Elson <jmelson@...>
To: <CAD_CAM_EDM_DRO@onelist.com>
Sent: Monday, February 07, 2000 10:33 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: How does G02 & G03 work?


> From: Jon Elson <jmelson@...>
>
>
>
> Darrell wrote:
>
> > Not wanting to cause any confusion but betweentwo points you could
> > have two
> > arc centers for any given I, J combination. One example would be two
> > lines
> > at 90 degrees to each other forming a square corner. Now filett that
> > corner
> > with a .5" radius. Assuming that the corner was at X0Y0 and the X and
> > Y
> > lines extended in the negative direction and the arc was clockwise
> > from X to
> > Y you would have an I.5 and J.5. EMC would cut what you want but a
> > FANUC
> > would use the I+.5 J+.5 to cut an arc of 270 degrees with both ends of
the
> > arc 90
> > degrees to the two lines.
> > I, J and K are very control dependant.
>
> But, the G-code used (G02 or G03) specifies the direction (CW or CCW) of
> the arc,
> and the current tool position and the command to move to a new
> coordinate specifies
> the direction of motion. SO, the control DOES have enough information
> to know whether
> the center of the arc is left or right of the path of the move.
> Therefore, it doesn't need
> any sign information on the I J K words. Allen-Bradley never used signs
> on their I J K
> words, either.
>
> Jon
>
>
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