Partdesign Tolerance (padding / cut)

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MRx
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Location: Tainan / Taiwan

Partdesign Tolerance (padding / cut)

Post by MRx »

Does anyone know where the tolerance of 0.2mm comes from when doing a partdesign pad/cutting?
This tolerance seems to be rather high to me, I'd prefer a tolerance of at least 0.01mm for modelling.


0.1mm:
0p1pad.png
0p1pad.png (12.85 KiB) Viewed 1699 times
0.2mm
0p2pad.png
0p2pad.png (12.33 KiB) Viewed 1699 times
0.3mm:
0p3pad.png
0p3pad.png (17.05 KiB) Viewed 1699 times
Top View:
0.2mm:
0p2v2.png
0p2v2.png (4 KiB) Viewed 1686 times
0.3mm:
0p3v2.png
0p3v2.png (1.72 KiB) Viewed 1686 times
chrisb
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Re: Partdesign Tolerance (padding / cut)

Post by chrisb »

How can we know without a file? Without FreeCAD infos? It's most probably a mistake in your modeling.
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MRx
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Location: Tainan / Taiwan

Re: Partdesign Tolerance (padding / cut)

Post by MRx »

I thought there could be an option somewhere.

I think this is a bug in opencascade, I have fixed it through the Draft workbench by creating the face manually and merging everything.
MRx
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Re: Partdesign Tolerance (padding / cut)

Post by MRx »

This is no bug in opencascade this is an issue in FreeCAD.

In the case before the vertexes have a certain tolerance
eg. 0.05 and 0.09 the minimum distance between the corner vertexes has to be 0.14mm once the distance is smaller than that the pocket operation blows up the model.
This can also lead to intersecting vertexes issues in the geometry checker.

Now on big models the issue can be small and unseen and followup issues might lead to absolute disasters ... how do I know it god damn happened to me.
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adrianinsaval
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Re: Partdesign Tolerance (padding / cut)

Post by adrianinsaval »

no file no gain as is sometimes said around here...
MRx
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Re: Partdesign Tolerance (padding / cut)

Post by MRx »

https://forum.freecadweb.org/viewtopic.php?f=3&t=65420

there was a file and no answer either, I think those who know about tolerances aren't reading that section of the forum too frequently...
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adrianinsaval
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Re: Partdesign Tolerance (padding / cut)

Post by adrianinsaval »

MRx wrote: Tue Jan 18, 2022 12:54 pm https://forum.freecadweb.org/viewtopic.php?f=3&t=65420

there was a file and no answer either
oh sorry for sleeping every now and then instead of lurking in the help forum 24/7 ;)
I think those who know about tolerances aren't reading that section of the forum too frequently...
This might be true but still, it's unreasonable to expect immediate answers in an online forum (although it happens some times).
Now the file you posted there is just a line, I'm guessing it's related to your complaint in this thread but it's not representative of what happens here.
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Re: Partdesign Tolerance (padding / cut)

Post by MRx »

I'm not complaining, I just don't expect too much either on certain topics.

I'm just happy to know about this problem in FreeCAD... it has hit me several times in the past and I did not know how to fix it and all the options in Part / PartWorkbench cannot fix such issues either.

Another issue like intersecting holes is still unsolved (there's a temporary workaround to add a chamfer / fillet; but once the part gets refined / down/upgraded - the problem is back again in the geometry checker).
I'm just concerned about followup issues since I've seen many problems with FreeCAD already.

To identify this issue now I only need to see pictures and the information given in the first thread to say that this is very likely a tolerance related on the vertexes :-)

----

FreeCAD should not allow entering the deadzone (intersecting tolerance areas of vertexes) - it's a recipe for disasters.
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adrianinsaval
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Re: Partdesign Tolerance (padding / cut)

Post by adrianinsaval »

I just don't expect too much either on certain topics.
well you certainly shouldn't expect much help here where we don't even know what you are doing or what is your intent or what operation is failing under what conditions, as I mentioned in another thread recently my crystal ball ran out of magic juice and I had to send it for refurbishing so unfortunately I can't guess what is at play here.

Anyways, these issues usually come from OCC not necessarily FreeCAD.
MRx
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Re: Partdesign Tolerance (padding / cut)

Post by MRx »

Did you understand the issue which I have posted?

Anyways, these issues usually come from OCC not necessarily FreeCAD.
Either way someone has to check for vertex intersections (taking the tolerances into account) when doing a boolean operation or the outcome can easily be a disaster.
Sometimes the intersection does not produce an obvious damage on the object - that's why I mean that for sure many freecad objects out there are silently damaged. And it's not the fault of the user, it's the fault of FreeCAD & OCC that no one is checking for that.

Seriously this issue has cost me weeks(!!) of debugging what this damage is about and how to fix it... I tried to remodel broken parts and hoped things will be better but no I end up in the same situation again and again. There's no button in FreeCAD and looking for a fix in the UI will not lead to any solution.
It has caused follow up issues in various other workbenches in FreeCAD when touching the specific broken faces.

I even exported the model to Rhino to fix things in Rhino3D and back-exporting it to FreeCAD to see how the result will be, but I was not happy with the bsplinecurves that freecad is putting into the exported files.
Last edited by MRx on Tue Jan 18, 2022 3:42 pm, edited 4 times in total.
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