Re: [CAD_CAM_EDM_DRO] Re: Help needed with G code

Raymond Heckert wrote:

>I always thought that the "I" parameter related to the X axis, and the "J"
>to the Y axis, and the "K" to the Z axis. Then, if the G19 gave a plane in
>the Y-Z plane, you'd use the "J" word and "K" word, but not the "I" word,
>as it would be meaningless. Or is that not how the parameters are used?
>

This is exactly how the RS-274D language specification says it is SUPPOSED
to work. Apparently, though, some CNC programs couldn't figure this out,
and did it their way.

>(I've never done arcs in other than the X-Y plane). Also (unless this is a
>lathe you're talking about), how are you going to prevent the cutting tool
>from gouging at the beginning and end of the cut. i.e. you'll start out
>with a concave radius equal to the tool radius, then as you transition up,
>and over the top of the arc, the surface will 'flatten' out, then
>continuing on through the rest of the arc, will become concave again. (I've
>long since deleted the original post, so I no longer know what I'm talking
>about).
>
>

Yup, that is a problem with this type of move. If you use a ball-nose
cutter
and either work a tool offset into the original parameters to the G-code
command, or use a cutter radius offset, it should do the right thing.
But, with a standard square-end mill, it would make an entirely different
cut, as you say.

Jon