Component Patterns
Component Patterns
(OP)
I have just wasted the better part of a day trying to fix a messed up assembly model. Somehow, my constraints were being described by SolidWorks as overdefined. As far as I am concerned, they were not. When I deleted the overdefining dimensions, SolidWorks claimed that my assembly was now properly defined. I could easily see that parts were not properly constrained, and it was possible to move them around, proving my point.
Several hours of very frustrated hacking around later, I gave up. I decided to delete all my fasteners, and try re-installing them. I started this by deleting the component patterns.
Surprise! The problem went away.
Somehow, my component patterns were screwing up the assembly constraints on my model.
I put this down as a helpful tip because my problem is solved. I just wish I understood what happened.
JHG
Several hours of very frustrated hacking around later, I gave up. I decided to delete all my fasteners, and try re-installing them. I started this by deleting the component patterns.
Surprise! The problem went away.
Somehow, my component patterns were screwing up the assembly constraints on my model.
I put this down as a helpful tip because my problem is solved. I just wish I understood what happened.
JHG






RE: Component Patterns
One thing I have learned is that "overdefined" can have different meanings and can drive you in wrong directions.
Example:
- you insert a part and make the horizontal plane of the part coincident with the horizontal plane of the assembly
- now you make the horizontal plane of the part coincident with the vertical plane of the assembly
- SW reports an overdefined assembly. In fact, that is not true because overdifened should mean that you have a set of POSSIBLE constraints, more than needed. In this example you have a set of IMPOSSIBLE constraints because a plane cannot be coincident with two orthogonal planes. SW should give different warnings.
- if you delete one constraint, the assembly is "surprisingly" underdefined (just because it was not realy overdefined).
Was I clear?
Another usual error is when you change the Aligned and Anti-aligned properties of matings. This can also drive you to incorrect overdefining information (in this case it is also a problem of a set of impossible constraints). When you need to change the orientation of a component, normaly you need to change the alignement of, at least, two mates (modify one mate, SW reports overdefining, change the other and now it's OK)
Regards
RE: Component Patterns
You are quite clear, but I am aware of all this. An optimal constraint layout is...
* plane to plane,
* plane to edge or line,
* plane to point.
Alternately...
* plane to plane,
* concentric (round surface to round line or point),
* plane parallel to line.
Both of these control six DsOF. It is often hard to do this, but in the case above, I succeeded. In any case, if I had screwed this up, turning off the offending constraint would have fixed the errors, and left my components unconstrained Deleting the component pattern would have had no effect.
JHG
RE: Component Patterns
But in my opinion, to be more clear, SW should have different icons according to the mating error nature.
Regards