On 2010-07-22, Jon Elson wrote:
Ignoramus24043 wrote:

2) Implementing a cut along an arbitrary shape, with several passes if
necessary

If I can do these two tasks separately, then I have a lot of
flexibility, as I could easily cut a square shaped hole in plate, egg
shaped, etc.

The generally suggested method is to ramp down while performing the cut,
rather than plunging in Z and then moving in XY. I have already
converted my "treprect" program that plunged first, then cut around the
rectangular shape, then made a finish pass at full depth. The new
version, which I haven't gotten up on my web page yet ramps down on the
first side of each level.

That actually makes perfect sense. Thanks for bringing this up.

Same applies to "milling out a deep pocket along an arbitrary shape".
Generating a shape is one thing, and removing material inside it (in
possibly several layers) is another.

If it is not a simple circle, oval or rectangle, then it may be better
to plan the whole thing on a CAD system. Bobcad/CAM, one of the
lower-level packages, will do this pretty much automatically. You give
the pocket outline, the depth, and set some parameters such as the
step-over and plunge increment, and have it draw an offset line to
compensate for the tool radius, and it will carve out the interior of
the pattern automatically. Pretty much any CAM system ought to be able
to do the same.

Sure. I will look into all of it.

i