bug in 3d contour

[hoeselYUQKY]

As a first step I wanted to do a 3d contour, but it generates bad moves that break the endmill because it starts moving at nearly full depth through uncut material, but I told it to use a small stepdown, so this should not happen. At some point it even managed to go at nearly full depth from one island to the next in a straight line.

[a.laasW8M6T]

Hi

This isn't a bug

3d contour is a FINISHING toolpath and therefore is not ware of large amounts of excess stock.

You really should use some sort of roughing toolpath(like 3d pocket) first to remove bulk material then come in with a finishing path.

3D contour probably isn't the best toolpath for this type of part.

You would probably be better to use Parallel with perpendicular passes

[hoeselYUQKY]

that's not the right answer. Yes it is a finishing toolpath, but it
should be aware that at this stage, the material is still not milled
and should not have moved at this depth. Instead it should retract,
just like it does in most other positions during the contour.

But anyway I did a parallel pass first (just because of this bug), but
it has to leave a bit extra material behind as otherwise the contour
is broken up in so many parts that it takes 26 hours just going up and
down and do a fragment of the contour. (I'm using the free personal
version, so no fast moves). Then after the contour I still need to do
an extra parallel to remove the extra material left behind by the
first parallel that wasn't removed by the contour.
Its an annoying "feature" that breaks endmills.

[seth.madore]

Yes, it is the right answer. The only thing that 3D finishing toolpaths are aware of is the model itself. You need to use a roughing toolpath first to clear out the extra material, leaving a small amount for the finishing toolpath(s)

[hoeselYUQKY]

well, this makes no sense to me.
If I wanted the contour to depend on a roughing pass first (the normal
usage), I would specify that and turn on rest. That would make sense.

What if the roughing pass didn't remove enough material? with your
answer in mind, it would still generate a contour path that might go
through material at full depth, if even for a small part that might
still be very bad. It is just asking for trouble and could easily be
avoided by removing a handful of bad moves and turn them into
retracts.

[programming2C78B]

thats not how CAM programs work! you're asking for some sort of maximum allowable machinable volume function.

[QCG6]

Rest machining doesn't correspond with roughing or finishing specifically. It can be used when finishing or roughing. It just makes fusion use the current IP stock to determine what/where it cuts.

3d contour is a finishing strategy and you need to use roughing strategies when there is too much material left in a given spot to use a finishing strategy

[hoeselYUQKY]

all I'm asking is that when it goes from one island to the other, it
does a retract first. I shouldn't assume the space between is empty if
it hasn't been milled yet. Note that it does retract all the time.
There are only a few positions in my piece where it doesn't do this.
It has nothing to do with some maximum volume or whatever. Even when I
would have milled most of it away but leaving 0.5mm stock, this kind
of moves will suddenly have to push through 0.5mm of stock at full
depth, instead of in small step downs as requested for the contour.
It's just not good!!!

[QCG6]

That's why you should rough to much closer than 0.5mm. Use 0.12mm as your radial and axial stock to leave for your roughing strategy

[hoeselYUQKY]

i know, I just mentioned it, because the software is perfectly capable
of determining if stock has been milled or not. Using that info it
should never cut at full depth when asked to do small stepdowns.

[hoeselYUQKY]

no, that's why the bug in 3d contour should be fixed, as it doesn't
matter how close you go, it will always cut some part at full depth,
whereas it isn't supposed to do that at all because I told it to use a
small stepdown.