(Sorry to retrace back in the thread. Kindly continue with BillZ's issue
)
I just now realized why the "contours" has such a large G64 (path interpolation) value. It is indeed so that 3D carvings come out correctly. But, not "correctly" in the way you and I think. When we say the toolpath acts correctly, we mean that it accurately matches what we told it to do. If we were to get out the calipers and measure some feature, why it should be what the model/design says it should be, right?
Yup, that's totally the way I see it too.
Except, what if the term "correctly" didn't really mean "accurately", but meant "without destroying the machine and breaking the bit and making a gawd-awful mess of the wood?" I mean, that's one form of "correct", right? Cutting aluminum all the time, I have more than my fair share of horribly broken end mills. By way of comparison, an off-sized part that finished being made is of more use and better than one that ruins the part, breaks a $50 bit, and makes me take a day to figure out how to prevent it from happening again. Right? That last part? That's the BAD stuff!
So if your goal in making the post-processor for 3D carving is to make the carving come out "close enough" dimensionally, but more importantly reliably "correct" in this new sense of not instilling panic in the user, then maybe having relatively loose path interpolation is actually a Good Thing. One easy way to do that might be to not allow the spindle to make "sudden moves". Because let's face it...when you're doing a VCarve/Aspire 3D Carve, it does raster-style, or planar (chew a little off the top each time). In planar, the "sudden moves" come in the XY plane, and that's perfectly normal, that won't too seriously affect the cut. But, check it out: in the raster-style, all of those "sudden moves" are at high-incline areas in that raster-line's path. Yeah...in the Z direction.
Plunging too quickly, trying to make walls too vertical, and edges too sharp, those are the things you're NOT going to have much success with a ballnose end mill. Sure there are some cases, but not like the raster mode Vectric uses. And so, they assume if you're going to take the time to do raster, there's significant detail in that...and you want it to come out properly.
One way to achieve it that doesn't require getting into the toolpath-generation guts of VCarve, it to just change how closely the CNC moves along the programmed path....which is conveniently what G64 does! In a raster toolpath, it essentially "rounds off" all those sudden moves up and down in Z. By effectively reducing that fast/sharp plunging, it would indeed have the desired effect of lowering the peaks in cutting stress. In aluminum, those stress-peaks spell destruction. In wood, often it just means a groaning noise that makes you look up, more hand-sanding in that area, and that's about it.
Maybe there IS a use for a G64 that large after all.
Now back to the new conversation....