×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Component Patterns

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

RE: Component Patterns

To solve mating problems (not by deleting the components but by redefining the constraints with the components in the assembly) requires practice and careful analisys.

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

(OP)
MacPT,

   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

My first post as not correct. When there's a mating error an SW window pops up giving more detailed information about the problem. In this window, the information differs according to the mating error, being more clear than the unique icon in the feature manager window. If you read this information (which I normally don't do, sorry) SW gives you some hints to solve the problem. But I never tested this information to see if it always point in the right direction.

But in my opinion, to be more clear, SW should have different icons according to the mating error nature.

Regards

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources