assembly mate problem sw2006sp4.0

Aug 28, 2006 1 Replies

I'm wondering if anyone else is seing something like this. I have a linkage mechanism (simple link members with hinge pins) where I want to make assy configs based on distances from the end of the moving linkage to one of the assembly reference planes. The last component on the end of the linkage can be mouse dragged around with the "Move Component" icon and the linkage moves as expected. If I try to create a distance mate from a point on this same component back to a plane, I get a message saying "Warning: This mate is over defining ....." as soon as I click the distance icon. I can OK the warning message and then put a value into the distance mate, and it sometimes gives a message "Plane and point are not the correct distance apart. Actual distance is xxx, desired is yyyy" where yyyy is the distance I want as a mate. On one occasion it applied the distance without this message and got me back to the assembly with a bunch of overdefined mates, mostly on the hinge pins. This is a very simple assembly with no limit mates or anything like that. Mate Diagnostics doesn't appear to be functional at all.



Is there a serious bug in the mates function again? (I remember fighting with stuff like this in the last millenium}



Thanks, Bill


SWX seems unreliable in respect of what you are trying to do. It frequently says things are over-constrained when they are not - this applies to both sketch relations and assembly mates.

One thing that may help (but you may be doing this already) is to ensure that all the mates that you are using prior to adding the distance mate do not try to control more degrees of freedom than necessary. By that I mean that (for example) a face-face coincident mate removes 3 D.O.F. , but the system will let you constrain 2 cubic components with 3 face-face coincident mates, which in theory accounts for 9 DOF - but of course we know that in the real world there are only 6 DOF. In other words, it allows you to over-constrain the components so long as the result is consistent.

Try where possible to use the 3-2-1 rule i.e. first mate removes 3 DOF, 2nd mate removes 2 DOF and 3rd mate removes the final DOF. In practice, this tends to mean using fewer face-face coincident constraints, and more face/plane-point coincident, and face-face parallel constraints.

It'll probably still fail, but at least you'll have the satisfaction of being able to swear about the s*it software!

John H

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