CAM roughing: different strange thing when not clearing voids

tl;dr: skip to example

I guess this is the “another topic”, suggested in the other “strange things” topic, about why I’ve been roughing with “clear voids”. And maybe why the first topic wasn’t supposed to be a thing at all…

With my setup, I always want to avoid cutting deep slots to avoid breaking long skinny cutters. I’ve been roughing with “inside only” and “clear voids” then outlining with “outside only”, “wide cutout” and “omit through”. That works[1]. It works just fine with small voids like simple holes, but larger voids burn more than optimal time. I’ve been thinking of asking for an option for roughing “inside only” and not “clear voids” to handle inner perimeters like outer perimeters, which I thought might become another topic, but maybe not.

Here’s an example workspace with four rings:

  • two with stepped tops (right) and two with sloped tops (left)
  • two smaller (far) and two larger (near)

roughing-inside-rings.kmz (316.4 KB)

All roughed with “clear voids” de-selected.

Note that for three of the four rings – the larger ring with stepped top and both smaller rings – the roughing op cuts a single full-thickness outline around the void. That is what recent K:M has “always” done IME. That’s what I assumed was normal when writing up the other “strange things” roughing topic. That’s also why I’ve been using “clear voids” to avoid cutting the deep slots.

For the one large ring with sloped top surfaces, the roughing op does not include the void cutout circuit. That avoids the deep slot (or cutting air inside a previously cut wide cutout) and sets up the part to continue with an outline op with “outside only”, “wide cutout” and not “omit through” to finish roughing the part.

That’s actually the behavior I’d like to use!

If the one shows intended function and the three show a bug, then the first “strange things” topic evaporates entirely, and takes a future suggestion/request topic with it.

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[1] for completeness: followed by an outline op with all options de-selected to finish the shape in the inside-outside transition zone around the outer edge. Which, for complete completeness, is not redundant around vertical perimeters when it’s a real finish pass after roughing with “leave stock” and then lying to the wide cutout outline op about tool diameter to get the effect of left stock around vertical sides for the 2nd no-options outline pass to skim off. Here is hidden foreshadowing of a future ask for a “leave stock” parameter for outline and non-follow-center trace ops…

well that is interesting. the inner pass should be on all the parts. so let me figure out what’s causing the difference.

I’m glad you like breaking stuff /wry smirk/.

My wrinkle is that, in context of how K:M rough and outline ops are working together, I’d really like an option to not have the inner though pass in the rough op. So that inside-only roughing and outside-only wide outlines match up around interior perimeters the same way as around the exterior perimeter. Enable the outline op in that workspace to illustrate how it works better for the one “broken” case than for the three nominally correct!