Invalid constraint index: 24

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drmacro
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Re: Invalid constraint index: 24

Post by drmacro »

NewJoker wrote: Wed Dec 07, 2022 10:59 am ...

It seems to be a bit of an exaggeration. Sketching on faces is normal in other CAD software
True, but that doesn't mean it is best practice for all or all cases, in FreeCAD or any other software.
and with TNP almost non-present it shouldn't be so risky to use it. Even now I keep sketching on faces and never encounter TNP. Maybe because I don't make significant modifications to my models and draw rather simple stuff but with a bit of care one can easily avoid issues that can be caused by sketching on faces.
True, but you can avoid it even more, especially as a new user, by avoiding sketching on generated geometry.

Besides, learning how to use the Attachment properties and the Attachment dialog for advanced advanced attachment techniques is a very useful thing to know.
Alternative workflows are just too tedious to use on a daily basis.
If you seriously embrace the Placement and Attachment of sketches it just becomes second nature/ muscle memory. The price is some time/tedium during the embracing. Making for generally more stable, maintainable, and editable models. Whether the reward of the later is worth the effort is of course the users decision.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
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NewJoker
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Re: Invalid constraint index: 24

Post by NewJoker »

Lonfor wrote: Wed Dec 07, 2022 12:33 pm It is not if you expend a whole night modeling and then, suddenly, the model explodes in such a way that it is impossible to repair.
So, in FreeCAD the hardcore approach at modelling is a must if you want a stable model.
By exaggeration, I meant saying that even with TNP fixed one should avoid sketching on faces. Have you tried modeling in Link Branch ?
chrisb
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Re: Invalid constraint index: 24

Post by chrisb »

NewJoker wrote: Wed Dec 07, 2022 10:59 am with a bit of care one can easily avoid issues that can be caused by sketching on faces.
What kind of care - except not changing things in the history before and praying - are you talking about?
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
Lonfor
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Re: Invalid constraint index: 24

Post by Lonfor »

NewJoker wrote: Wed Dec 07, 2022 1:12 pm Have you tried modeling in Link Branch ?
Never used it and I choose not to because of compatibility issues with the main branch. On the other hand, I used to model with NX for many years and it is almost immune to TNP, and even when it fails, a graceful image preview of the missing reference will show up on the right side of the screen with some suggestions on how to repair it, so I positively know how top commercial softwares work that are way, way ahead of the Link Branch.
That said, FreeCAD is a different beast, not mature yet but with an incredible potential, and it is a matter of to learn how to ride it.
drmacro
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Re: Invalid constraint index: 24

Post by drmacro »

NewJoker wrote: Wed Dec 07, 2022 1:12 pm ...
By exaggeration, I meant saying that even with TNP fixed one should avoid sketching on faces.
Indeed, I avoid sketching on faces, religiously. ;)
Have you tried modeling in Link Branch ?
Yes, and I don't use it.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
ProApe
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Re: Invalid constraint index: 24

Post by ProApe »

Hi,

so this bad geometry has to be fixed first.

And one should not sketch upon faces, although that would of course be the simplest method. By the way, I have followed some tutorials where this rule wasn't respected, even by authors who seem to be very professional!

What is the correct one? A new tarpaulin at the height of the pad on whose face you are not supposed to draw? And then bring in the required elements with the tool External geometry (which looks like a box with which a blast is triggered)?

Kind regards
ProApe
drmacro
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Re: Invalid constraint index: 24

Post by drmacro »

ProApe wrote: Sat Dec 10, 2022 4:48 pm Hi,

so one should not sketch upon faces, although that would of course be the simplest method.

What is the correct one? A new tarpaulin at the height of the pad on whose face you are not supposed to draw? And then bring in the required elements with the tool External geometry (which looks like a box with which a blast is triggered)?

Kind regards
ProApe
A new sketch is typically suffice. Use the Attachment offset to place it. The use external geometry from another sketch, since external geometry from generated geometry will also cause TNP.

Using sketch geometry is less likely to cause TNP, but it can as well.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
chrisb
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Re: Invalid constraint index: 24

Post by chrisb »

ProApe wrote: Sat Dec 10, 2022 4:48 pm What is the correct one? A new tarpaulin at the height of the pad on whose face you are not supposed to draw?
I'm not sure if "tarpaulin" means "DatumPlane". You usually don't need it.
For the general case, where you want some Sketch00Y at the end of a Pad based on Sketch00X, you attach Sketch00Y in the same way as Sketch00X and use an expression "Pad.Length" for its z component of the AttachmentOffset.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
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