[SOLVED] asymmetric fillet joint issue

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fc_tofu
Posts: 653
Joined: Sun Jan 05, 2020 4:56 pm

Re: Fillet issue in FreeCAD 0.19

Post by fc_tofu »

fc_tofu wrote: Wed Jun 24, 2020 10:44 am Here, FreeCAD Bevel's algo appears obviously weaker than commercial apps.
Just now, a friend helped make comparisons with 2 commercial apps.

Case 1. co-vertex cut
app 1 (below)
fsc_2020-06-24_184358.jpg
fsc_2020-06-24_184358.jpg (12.59 KiB) Viewed 2491 times
fsc_2020-06-24_191057.jpg
fsc_2020-06-24_191057.jpg (9.81 KiB) Viewed 2479 times

app 2 (below)
fsc_2020-06-24_184428.jpg
fsc_2020-06-24_184428.jpg (14.04 KiB) Viewed 2491 times
fsc_2020-06-24_191137.jpg
fsc_2020-06-24_191137.jpg (6.99 KiB) Viewed 2479 times
Case 2. co-vertex cut avoided
app 1, app 2, viewed same as FreeCAD.
Attachments
bevel_test_new.FCStd
(40.46 KiB) Downloaded 69 times
fc_tofu
Posts: 653
Joined: Sun Jan 05, 2020 4:56 pm

Re: Fillet issue in FreeCAD 0.19

Post by fc_tofu »

fc_tofu wrote: Wed Jun 24, 2020 10:56 am Just now, a friend helped make comparisons with 2 commercial apps.
Attachment is:

1. Benchmark file STEP file, without fillet (exported from .FCStd file of above post)
fsc_2020-06-24_193143.jpg
fsc_2020-06-24_193143.jpg (28.18 KiB) Viewed 2473 times
2. Frozen view of FreeCAD
usage: unzip file >FreeCAD >menu >View >Freeze display >Load views

Anyone who have access to commercial CAD apps could make test by self.

New test shows that Chamfer operation are affected by the issue in similar way.
So, perhaps, call this "asymmetric fillet joint" issue, "uneven fillet joint" issue?
Attachments
frozen_view.zip
(459 Bytes) Downloaded 69 times
test_unfillet.step
(13.12 KiB) Downloaded 59 times
gdurrens
Posts: 22
Joined: Tue May 26, 2020 9:49 am

Re: Fillet issue in FreeCAD 0.19

Post by gdurrens »

Wow @fc_tofu, what an investigation !

Thanks a lot for this.
I've opened your files and tried to fillet. I get the same results.

At least now we know better how to name the issue.
Could also be "Dual miter joint fillet" issue, what do you think ?

I'll try as much as I can to avoid coplanar situations but it seems to me that they are very frequent. I think I need to learn better how to properly model with FreeCad.

How do I change the topic's name ?
kisolre
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Re: Fillet issue in FreeCAD 0.19

Post by kisolre »

gdurrens wrote: Thu Jun 25, 2020 2:52 pm How do I change the topic's name ?
You edit your first post and change its Subject.
fc_tofu
Posts: 653
Joined: Sun Jan 05, 2020 4:56 pm

Re: Fillet issue in FreeCAD 0.19

Post by fc_tofu »

gdurrens wrote: Thu Jun 25, 2020 2:52 pm
Could also be "Dual miter joint fillet" issue, what do you think ?
I have never thought fillet a serious problem before your op.

Image

To reillustrate, the issue is not that Edge1/2/3 intersect at Vertex4. But, Edge1 and Edge3 are asymmetric to Edge2. Or say, the angle between Edge1 and 2, the angle between Edge2 and 3, they are not equal value.

Your "Dual miter joint fillet", doesnot contain the meaning of "asymmetric". If edges are symetric here, fillet is very easy for FreeCAD (and any other 3D app).
My "asymmtric fillet joint" is also confusing, for SolidWorks use term "asymmetric fillet" refer to different radius at 2 ends of a fillet.

Change or not op title, I think the term is not a problem. If you think your question is sovlved, you could add [Solved] prefix to your title. If you are still waiting for more answers, leave it untouched.

I made new benchmark file where the angle deviation is enlarged. This time, FreeCAD and app1 broke model, but app2 still succeed.

benchmark (below)
fsc_2020-06-26_205500.jpg
fsc_2020-06-26_205500.jpg (33.06 KiB) Viewed 2323 times
FreeCAD (below)
fsc_2020-06-26_205509.jpg
fsc_2020-06-26_205509.jpg (22.67 KiB) Viewed 2323 times
app1 (below)
fsc_2020-06-26_205533.jpg
fsc_2020-06-26_205533.jpg (17.36 KiB) Viewed 2323 times
app2 (below)
fsc_2020-06-26_205548.jpg
fsc_2020-06-26_205548.jpg (15.42 KiB) Viewed 2323 times
Till now, the algo of app2 seems the only reliable solution to a "asymmetric fillet joint".

The algo of fillet is not at FreeCAD, but at OCCT (geometry engine of FreeCAD, standalone project).
The digging here is just for fun. It finnally tells the difficulty of an apparently-easy problem.
Attachments
fillet_export_fc019.step
(28.41 KiB) Downloaded 72 times
gdurrens
Posts: 22
Joined: Tue May 26, 2020 9:49 am

Re: asymmetric fillet joint issue

Post by gdurrens »

Thanks fc_tofu for the digging (and the fun then !)

Yeah I think we got to the bottom of this : The OCCT engine is limited in this situation.
I'll keep an eye on the evolution of their engine.

Cheers
gdurrens
Posts: 22
Joined: Tue May 26, 2020 9:49 am

Re: [SOLVED] asymmetric fillet joint issue

Post by gdurrens »

thanks freecad-heini-1 for joining the investigation !

Unfortunately this does not work on the original piece.
Attachments
Peek 2020-06-29 14-43.gif
Peek 2020-06-29 14-43.gif (924.42 KiB) Viewed 2219 times
Peek 2020-06-29 14-44.gif
Peek 2020-06-29 14-44.gif (759.95 KiB) Viewed 2219 times
gdurrens
Posts: 22
Joined: Tue May 26, 2020 9:49 am

Re: [SOLVED] asymmetric fillet joint issue

Post by gdurrens »

first gif seems to be corrupt so I post a new one here
Attachments
Peek2.gif
Peek2.gif (862.66 KiB) Viewed 2213 times
fc_tofu
Posts: 653
Joined: Sun Jan 05, 2020 4:56 pm

Re: [SOLVED] asymmetric fillet joint issue

Post by fc_tofu »

I simplified OP's model,even removed a tiny edge (about 80um long.)
So, this time the sample file is quite simple, only a 4-faces shell.
Could you give another try? Or help diagonize.
Fillet radius 1mm.
fsc_2020-06-29_211135.jpg
fsc_2020-06-29_211135.jpg (10.36 KiB) Viewed 2204 times
Attachments
asymmetric_fillet_sample.step
(14.58 KiB) Downloaded 50 times
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