Seeking tips on identifying missing constraints in Sketch

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ManOfScience
Posts: 12
Joined: Fri Jan 21, 2022 4:19 pm

Seeking tips on identifying missing constraints in Sketch

Post by ManOfScience »

Would greatly appreciate if a good Samaritan is willing to look at my file and advise on how to figure out what constraints are needed.

It looks like all of the vertices are green when I click "find DOF", but lots of the edges are not green but I have not figured out why.
Lego Shelf Rings2.FCStd
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Any advice?
drmacro
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Re: Seeking tips on identifying missing constraints in Sketch

Post by drmacro »

You have multiple instances of 0 mm dimensional constraints,, it is much better to geometric constraints and avoid 0 mm constraints.

This sketch has way too many constraints. You should use multiple sketches.

There is some symmetry that you could take advantage of a simplify/reduce the constraints making each sketch easier to read and maintain.

To find missing coincident constraints, use the Sketch Validate tool or just grab lines and attempt to move them.
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Screenshot from 2022-12-04 20-13-17.png
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Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
ManOfScience
Posts: 12
Joined: Fri Jan 21, 2022 4:19 pm

Re: Seeking tips on identifying missing constraints in Sketch

Post by ManOfScience »

Thanks DrMacro!
I will have another go at it starting with a symmetry line and change the 0mm distances to vert or horizontally equal.
I will also do some more studying to see if I can do the same 2 objects in 2 separate sketches and then constrain them together afterwards - this was my preference anyway but I gave up and thought it would be easier if I did it all in the same sketch. I now see that it maybe isn't easier.

Thanks for the advice - I will persist! :)
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papyblaise
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Re: Seeking tips on identifying missing constraints in Sketch

Post by papyblaise »

by dividing into 3, it goes much better, I used your sketch as master without trying to improve the rating

there are many unclosed points
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GeneFC
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Re: Seeking tips on identifying missing constraints in Sketch

Post by GeneFC »

ManOfScience wrote: Mon Dec 05, 2022 5:19 am I will have another go at it starting with a symmetry line and change the 0mm distances to vert or horizontally equal.
It sounds like you may be confusing "same position" with "connected". Two points with a relative distance of 0 mm are not automatically connected. That is why there are so many DOFs left.

Rather than set a distance or an equal constraint you need to make sure that intended connections are really connected. Use "coincident", "tangent", etc.

Gene
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Shalmeneser
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Re: Seeking tips on identifying missing constraints in Sketch

Post by Shalmeneser »

:idea:
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