Re: 3D Contouring - Loss of Accuracy

Hi Jon,

What you say is EXACTLY right! I have noticed that you do need enough
precision so that coordinates for arc's DO change enough (G03 X.123
Y.456 I-1.0 J-1.0) from the previous coordinate so that they are not
mistakenly identified as FULL CIRCLES! I ran into this when I tried a
small endmill, and got some really small arc's requested. I upped the
number of digits in the Gcode to get around this (my program thinks that
any arc that uses the SAME X and Y (or Z for other planes) coordinates
is a FULL CIRCLE! Maybe there is another way to detect this! I'm
thinking of putting in a warning dialog box for "full circles" in the
program, in case there AREN'T any!

Alan KM6VV


Jon Elson wrote:

>
> Peter wrote:
>
> >Visual Mill, my CAM software can specify however many digits to output
> >for each position - I've tried up to 8 digits.
> >
> >
> When running in absolute coordinate mode, NOTHING in the g-code should
> affect the
> ability to get back to the same location. (In relative, you have to add
> up all the moves so far,
> to return to the same pos, so that complicates the issue drastically
> with roundoff error.)
> In Abs., any time you say X0.0, you should get right back there. If
> not, the program has
> a SEVERE bug in its arithmetic, and shouldn't be used.
>
> Jon
>
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