class 'ValueError'>: Datum - error in Basic Part Design Tutorial

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bowden_p
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class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by bowden_p »

Hi,
I am totally new to FreeCAD, and so am following the Basic Part Design Tutorial as a starting point.
When trying to add the Length constraint to the top side in the sketch I get the error :-
class 'ValueError'>: Datum 10.00 mm for the constraint with index 10 is invalid

Similar for any other side.

I'd appreciate help on how to correct this problem - doubtless simple, but I have no clue as to where to look.
I have FreeCAD 0.20, running on Windows 10.

With thanks, Paul.
edwilliams16
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by edwilliams16 »

I'm not seeing any 10 mm reference in [url]s://wiki.freecadweb.org/Basic_Part_Design_Tutorial[/url], so it's not clear at what stage you are stuck. You should upload the file as far as you have progressed.
bowden_p
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by bowden_p »

Thanks edwilliams16.
Sorry, the actual length in question is 5mm for the top of the sketch ("Create the sketch", point 6.), but it doesn't matter what I enter, the same error occurs. I am guessing there must be some setup restriction here, but I don't know where to find it!
Thanks, Paul.
chrisb
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by chrisb »

Please upload your file where you have added everything up to that point. I guess that you have added some other conflicting constraint or that you have added inadvertently additional geometric elements.
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Syres
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by Syres »

It doesn't help when the image https://wiki.freecadweb.org/images/7/78 ... rofile.png doesn't match the instructions regarding the constraints (hint: 26mm).
Bance
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by Bance »

Syres wrote: Mon Jun 27, 2022 8:51 am It doesn't help when the image https://wiki.freecadweb.org/images/7/78 ... rofile.png doesn't match the instructions regarding the constraints (hint: 26mm).
Which tuto are you looking at? The one I see is correct, Point 5
Syres
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by Syres »

Bance wrote: Mon Jun 27, 2022 9:15 am Which tuto are you looking at? The one I see is correct, Point 5
Yes, I'm looking at the same, it's supposed to be an Equals constraint with only one 26mm dimensional constraint, I would have the instruction changed so it's not an Or situation, remember complete newbies expect everything in a tutorial to look exactly the same as their screen even if we know it doesn't always have to be the case.
Bance
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by Bance »

Yes I see, I'll make an addition later....
Bance
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by Bance »

Done, I changed the image, and added a note about redundant constraints.
bowden_p
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Re: class 'ValueError'>: Datum - error in Basic Part Design Tutorial

Post by bowden_p »

Gentlemen,
Many thanks for all your inputs. The tutorial I am using is "wiki.freecad.org/Basic_Part_Design_Tutorial".

I abandoned my first effort to follow it, but now have repeated the "Create a sketch" - points 1 to 7 sequence - successfully.

I suspect that I may have had some redundant constraints first time round, as I repeated some points - not seeing any resulting change.
I suspect that my first drawing was a little too "perfect" with exact horizontal, vertical and a closed polyline finish.

Would such a drawing with needlessly applied constraints cause the problem I saw to occur?

With thanks, Paul.
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