What is the proper constraining technique? How do i find it?

[GaTechTheron]

With what I'm trying to do, my parts have to be constrained effectively, efficiently, and basically... perfectly. Is there some type of online documentation to teach proper constraining, or can someone give me a quick rundown?!?

Thanks a bundle

 

[catiajim]

Just remember that each and every part has 6 degrees of freedom - 3 translation and 3 rotation. Watch how many of these are are reduced with each constraint. Remember though, it is tied to both the constraint and the geometry selected - coincident between points will lock 3 translation degrees, but no rotation, while betweeen planes will lock one translation and 2 rotation.

 

[solid7]

And sometimes, you have to "best fit" your rotation and orientation, because geometry may already be created, or created from a translated part. (and not practical to "correct")

In this case, you may have to create geometry that best orients the part, but doesn't fall within the theoretical "perfect" placement defined by the modelling kernel. You would have do make your own planes, points, and lines in the mating models, and manually constrain to them.


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[GaTechTheron]

You got it solid! When I was creating sections of the part, then were all being constrained from the absolute axis... when I used points and planes... not only was my part fully constrained but I was able to insert it from a catalog onto ANY plane without a problem

 

[solid7]

I got the wrong idea - I was speaking of constraining assemblies, but if you are talking about constraining sketches, that is a different story.

Constraining sketches does not have the "six degrees of freedom" that catiajim spoke of - it relies more on an XY coordinate type method. That is, you need to first define a "datum", which can be a projected element, or if you are close to the absolute planes, you can intersect them into the sketch, and fix them as an "absolute" reference, of sorts. It all depends on what you want to do. But you really need to fully constrain all the elements relative to one another, and then have 1 object to constrain the whole thing to.

Of course, there are so many ways to constrain, but this is the basic method. Use constraints in context. (somewhat like dimensioning

What are you trying to design and constrain? Setting the context will help determine an appropriate method.



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