Re: Re: How does G02 & G03 work?

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 I0 and J.5. EMC would cut what you want but a
> FANUC
> would use the 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