can't get any op on vertical face.

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freman
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can't get any op on vertical face.

Postby freman » Tue Oct 15, 2019 2:16 pm

Hi,

I want to cut a vertical face to finish its dimension, have a couple of mm to remove. I do not want to remove the stock and set the work with this face horizontal but combine this with two other ops in the same file.

I have selected the face but none of the path tools seem to be willing to deal with a vertical face, even 3Dsurface refuses:

Code: Select all

<Path.Area> Area.cpp(1281): project failed
<Path.Area> Area.cpp(1423): empty projection
I'm working on clone2.face8 in 'under-job'.

why can't I cut down the side of this face?

TIA.


OS: Linux (LXDE/LXDE)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.17672 (Git)
Build type: Unknown
Branch: (HEAD detached at ffb4aa5dc)
Hash: ffb4aa5dcfc0f0b6fb37161fd1c820ade167eb04
Python version: 2.7.16
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedKingdom (en_GB)
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face-area-problem.FCStd
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pl7i92LCNC
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Location: RLP DE

Re: can't get any op on vertical face.

Postby pl7i92LCNC » Tue Oct 15, 2019 5:34 pm

you can enter manuell G-code to get this done
or simply draw a sketch of the path yopu like and select it
with standard path along edge
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freman
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Re: can't get any op on vertical face.

Postby freman » Tue Oct 15, 2019 7:09 pm

Yes, thanks, I did do this by hand coding: it's sometimes quicker than struggling with FreeCAD for three hours, but the question is why can't I get FC to create a path on it? I should be able to get this all in one file and let it run.

Neither should I have to start making supplemental fake geometries to trick FC into making a path. I can contour a profile but I cannot do one face?

It may be because there is some material above ( which the first op removes ) but it is not smart enough to be able to take that into account, though I don't think it's even getting that far. I seems to fail when the area normal is perpendicular to the tool axis. At least that seems to be what is causing it to fail ( at least in the 3Dsurface case ).
chrisb
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Re: can't get any op on vertical face.

Postby chrisb » Tue Oct 15, 2019 8:54 pm

Moved to Path forum.
chrisb
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Re: can't get any op on vertical face.

Postby chrisb » Tue Oct 15, 2019 9:10 pm

The pocket doesn't work without a base at the bottom or an enclosing around it. You can use Contour with a depth of -28, which would do some extra moves around the object.
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freman
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Re: can't get any op on vertical face.

Postby freman » Tue Oct 15, 2019 11:03 pm

To remove the possibility of overhanging stock , I'll take this up to the vertical face ( face18 ) above that noted above.

The second icon on the toolbar has the hover hint "Profile based on face or faces". Presumably a single face qualifies for that tool. This gives the same failure as the 3Dsurface path tool:

Code: Select all

Profiling Select Mode
<Path.Area> Area.cpp(1281): project failed
<Path.Area> Area.cpp(1423): empty projection
PathProfileFaces.ERROR: Unable to create path for face(s).
It seems that there is a dot product being done on the normal vector ( probably with the tool axis ) and if this returns zero, it bails out with red error messages.

I may be misunderstanding what this tool is supposed to do but it does not seem to do what is on the box in this case.

Similarly 3Dsurface tool says: "Creates a Path 3D pocket object based on face or faces".

Code: Select all

Pocketing Select Mode
PathPocket.INFO: Updated obj.FinalDepth.Value and self.depthparams to zmin: -5.67369
<Path.Area> Area.cpp(1281): project failed
<Path.Area> Area.cpp(1423): empty projection
Traceback (most recent call last):
Maybe someone can explain what the problem is here.

The pocket doesn't work without a base at the bottom
Ah, "a face " has to be the bottom.
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freman
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Re: can't get any op on vertical face.

Postby freman » Tue Oct 15, 2019 11:42 pm

Facing operations also reject a vertical face. So in short it seems that there is no path tool capable of cutting down a face.

It can be worked around by making a fake geometry to provide a horizontal plane at the bottom to work down to but no way to use the vertical plane or straight edge to do the same job.

I can pocket or profile a horizontal surface or a close circuit of edges but there's no tool to profile a straight edge or a non closed form like the semi cylindrical ends of this shape. This seems to be missing spanner in the tool box.

Since this is already achieved when it is part of a close profile why is not possible if it is not closed?
herbk
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Re: can't get any op on vertical face.

Postby herbk » Wed Oct 16, 2019 6:10 am

Hi freman,

i have cases like yours to sometimes. As workaround i add a "helper pad" at the needed level.
Gruß Herbert
chrisb
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Re: can't get any op on vertical face.

Postby chrisb » Wed Oct 16, 2019 7:27 am

freman wrote:
Tue Oct 15, 2019 11:03 pm
I may be misunderstanding what this tool is supposed to do but it does not seem to do what is on the box in this case.

Code: Select all

...
<Path.Area> Area.cpp(1423): empty projection
...
All the Path tools work in XY plane only, that's the reason why there is a clone in the job which you can turn around. If you select a vertical face there is an empty projection int XY-plane. You can only select the top plane and create a profile which goes all around and thus mills on that way your vertical face as well.
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freman
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Re: can't get any op on vertical face.

Postby freman » Wed Oct 16, 2019 7:50 am

Thanks, herbk, that sounds similar to what pl7i92LCNC suggested.

I'm interested in getting FC to support milling vertical faces rather than adding fake geometries work around the short comings.

I was thinking I was missing the way to use a tool but it seems all the current tools have gown out of a common 2D code base where everything is based on vertical footprint. This means even the 3Dsurface tool instantly rejects any face parallel to the tool axis. This seems to common code used in all tools.

Having noted that the paths needed to cut such a vertical face are already produced as part contour or pocket paths, it seems that it is simply a case of not rejecting vertical faces off the bat and applying existing code to make the path. Maybe this could be wrapped as a new tool to make it simpler to develop but it seems the heavy lifting has already been done.

For example, if the area test was skipped it seems that the " profile based on edges" tool could cut both sides of a straight line. It would not be too hard to stop it doing both sides and the face is cut. ;)