Can't join manifolds

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mrdic
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Re: Can't join manifolds

Postby mrdic » Fri Jun 12, 2020 10:30 pm

tanderson69 wrote:
Fri Jun 12, 2020 4:23 pm
mrdic wrote:
Fri Jun 12, 2020 2:32 am
... add the individually lofted runners as the original workflow requires
Where was that spelled out as a requirement?
I suppose it could be argued that additive lofts to a part are concurrent single body operations, but there isn't a notional base that they're added to, IMO. Reminds me of Big Bang theory. The thread's called "can't join manifolds" and they're all termed "additive", which doesn't support the single body notion, unless that's dark matter. Just a whimsical reflection.
fc_tofu
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Re: Can't join manifolds

Postby fc_tofu » Sat Jun 13, 2020 4:25 am

mrdic wrote:
Fri Jun 12, 2020 7:07 am
ACIS wouldn't shell my FC model as .stp, but the usual thing would be a bit of slice'n'dice to find the area of greatest convolution, the show stopper, and fudge that.
From above posts. I have a feeling that, in terms of Boolean and Offset/Shelling, ACIS and OCCT are not quite different.
But the "Branched Loft" is quite a magic of ACIS. Is this only included in Fusion360? Howabout Inventor and AuotCAD?

And the essense of "Branched Loft" is aproximation or subd(Tspline)?
Hope someone share a STEP file of "Branched Loft".
mrdic
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Re: Can't join manifolds

Postby mrdic » Sat Jun 13, 2020 5:49 am

I use TurboCAD Platinum and SharkCAD Pro, both use ACIS, and both have the branched loft function. You declare the trunk profiles first, then the successive branches, then finish. It's been in TurboCAD and PunchCAD/SharkCAD since 2007 or 2008, and it's trouble-free but not frequently used. Latest versions of TurboCAD and SharkCAD Pro have CATIA, SW, Pro/E_Creo, NX, Inventor, SolidEdge import and others, they're useful as translators too. Autodesk (Fusion, Inventor) bought a permanent ACIS license at ACIS V7 (solids in .dwg are ACIS V7 compatible), then went with their own kernel development. Fusion and Inventor will import ACIS current .sat and .sab binary format files, but they export .sat/sab v7. They also bought T-spline technology, mentioned by that Fusion developer, that was originally available as a plug-in for Rhino and SolidWorks, it works pretty much by making each facet of a mesh a nurbs surface, tangential to its neighbours. It's a reverse engineering methods to get nurbs out of mesh but it doesn't make the model parametric, although I think I remember that it does recognise cylindrical, conical, planar features.
The zip attached is ACIS' branch loft of the internal profiles and outward shelling in TurboCAD.
Attachments
fan manifoldACIS.zip
(803.23 KiB) Downloaded 10 times
fc_tofu
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Re: Can't join manifolds

Postby fc_tofu » Sat Jun 13, 2020 11:14 am

mrdic wrote:
Sat Jun 13, 2020 5:49 am
The zip attached is ACIS' branch loft of the internal profiles and outward shelling in TurboCAD.
Many thanks for your sharing.
fsc_2020-06-13_184404b.jpg
fsc_2020-06-13_184404b.jpg (70.56 KiB) Viewed 367 times
The algorithm is good. Tiny intersected detail in the stem are simplified out to prevent geometry failure.

BTW, all models in this thread, when reimported as STEP, cause many BOP errors in FreeCAD, mainly "InvalidCurveOnSurface", "SelfIntersection".
Have no clue yet.
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papyblaise
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Re: Can't join manifolds

Postby papyblaise » Sat Jun 13, 2020 4:56 pm

all models in this thread
Not at all ... :lol:
I spend a long boring raining day to do a next one , it isn't the exact look whith a 5 round legs , but this one answer the objective
Just finish the last leg because the file became too large
Attachments
manifold carre2.FCStd
(797.75 KiB) Downloaded 4 times
manifold carre2.PNG
manifold carre2.PNG (23.4 KiB) Viewed 344 times
fc_tofu
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Re: Can't join manifolds

Postby fc_tofu » Sat Jun 13, 2020 5:36 pm

papyblaise wrote:
Sat Jun 13, 2020 4:56 pm
all models in this thread
Not at all ... :lol:
I spend a long boring raining day to do a next one , it isn't the exact look whith a 5 round legs , but this one answer the objective
Just finish the last leg because the file became too large
Check result of .FCStd
fsc_2020-06-14_012659.jpg
fsc_2020-06-14_012659.jpg (96.84 KiB) Viewed 336 times
Check result of reimported STEP
fsc_2020-06-14_012917.jpg
fsc_2020-06-14_012917.jpg (98.17 KiB) Viewed 336 times
Basically, I feel,
1. "SelfItersect" and "C0" error, are native in .FCStd
2. "InvalidCurveOnSurface" error, arises from STEP importer/exporter. Seems only Bspline edges/faces are involved.

ps. a former thread about BOP errors when STEP reimported
https://forum.freecadweb.org/viewtopic. ... 4&start=30
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Willem
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Re: Can't join manifolds

Postby Willem » Mon Jun 15, 2020 12:02 pm

wATCH THIS VIDEO
phpBB [video]
chrisb
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Re: Can't join manifolds

Postby chrisb » Mon Jun 15, 2020 12:58 pm

Great ideas and details in that video! Tiny drawback: for making the first connect of the two bodies he should have taken the hole bodies and not the feature inside.
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raidho36
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Re: Can't join manifolds

Postby raidho36 » Tue Jun 16, 2020 10:00 am

I've seen this video before starting the model; this method does not seem to work when using heterogenous profiles - union operation fails.
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papyblaise
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Re: Can't join manifolds

Postby papyblaise » Tue Jun 16, 2020 10:44 am

The union operation fails almost every time,
The only one that seems to work is to make each leg with a different outlet diameter of 0.1mm each including for the interior