Mate Problems with large assembly 2

[waddellr]

This is kind of hard to explain but it is driving me crazy. I will make up a large assembly of these bi-fold doors and as I go along everything works fine. Then I will start moving the door to make sure they will open and close. They will work then i find something to tweek and I will get massive rebuild mating errors (Over defining, un-solvable, and not-paralel)

I have tried it with different sub-asseblies and then with more top level parts. I'll have it working perfectly then i will open up a part or switch back to it and it is all messed up. Or I will go home for the night and come back in the morning and it will not load properly with messed up mates.

What is the problem, I've been suppressing and unsuppressing mates and eventually can get it to work with all the mates good then it will screw up again. It is driving me crazy what could be wrong.

Mind you I have made the same assebmly 5 different times 5 different ways with them all failing eventually.

Thanks

 

[Theophilus]

Are you constraining the angles between the door panels in any way? I've noticed SW will sometimes flip an angle mate to a backward state (-180*) somewhat randomly, depending on what the mate was based upon (edges, planes, surfaces, sketch lines).

On what were your mates based, and did you use any angles or angle restrictions (such as limit mates)?

Jeff Mowry

http://www.industrialdesignhaus.com

Reason trumps all. And awe trumps reason.

 

[CorBlimeyLimey]

Having too many mates (300) at the top level can cause problems. Are you near this limit?


Helpful SW websites FAQ559-520
How to get answers to your SW questions FAQ559-1091

 

[handleman]

Here are some more things that I have seen cause problems:

1. Mates to patterned instances of components, especially feature-based component patterns

2. Tangent mates

Bifold doors sound like prime candidates for having tangent mates.

 

[waddellr]

As far as my mates go; top level I have 79 mates. I don't have any tangent, limit, or angle mates. I have not mated to patterned instances and mated faces instead of edges.

And for the record, I closed it last night working, and this morning it opened up with mating problems

Thanks for the help

 

[smcadman]

I am assuming the hinges are sub-assemblies. Your problem might be with flexible sub-assemblies.

Flores
SW06 SP4.1

 

[Theophilus]

Tangent and angle mates can sometimes be a problem with the "flip" issue I first mentioned.

smcadman brought up something to check out--whether your doors are subassemblies set to flexible. If not, perhaps you need to further constrain the doors a bit. You're essentially working with triangles of varying stature by creating these folding doors. Your hinge should be a coincident or concentric mate (stable in this instance). But do you have anything holding the edges of your doors in check, such as coincident mates along an edge? If not, these doors will be unconfined just enough to allow SW some interpretation error (at least that's what I think it is--SW sometimes misinterprets things like this when only semi-confined). Try to get your movement confined by your mates to allow only the movement you really need.

For instance, you'll need the coincident/concentric mate between two folds of the doors. The other edge of each door may be made coincident to a plane (or mate the centers of the end faces of the doors in this way). You don't want to work with single points or corners, since this allows other possibilities of motion, other than the simple linear motion that causes folding of doors.

If this still doesn't cooperate, perhaps you can check the FAQ section about posting files for us to check out to see if we can help further.

Jeff Mowry

http://www.industrialdesignhaus.com

Reason trumps all. And awe trumps reason.

 

[gmarken]

For what is worth, Waddellr is not alone. I have had similar problems. In a large assembly (appoximately 200 mates)all the mates are satisfied, no errors. The file is saved. I go home. When the assembly is opened the following day, there will be mate errors. I fix the errors save the file and the same thing occurs. This has happened several times. I find that angle limit mates are usually the culprit.

 

[brengine]

I have seen this before too. Trying to decipher what the User did to get these errors, I found that the ordering of the components was completely random (and hard for me to debug which mates were constraining which motions). I suppressed them all, and then un-suppressed them one at a time while also reordering them into (what I fell was a) more logical order...i.e. components were ordered from the floor to the end tooling. I know this makes no sense, but by the time everything was unseppressed...there were no errors. We closed and opened the assembly a couple times and still no errors. I have done this twice in the last year or so, and somehow it fixed the problems both times.

Ken

 

[CSEM2004]

Are all the elements in the top level assembly fully constrained or are some unconstrained to allow you to open and close the assembly? Do you have any features in the top level assembly?

In addition to angle and tanget mates sometimes wanting to behave like you've inverted the mate (on their own), I've noticed problems with extrude features on top level assemblies. If you've moved the parts from the original postion they were in during mating, SW seems to occasionally become confused. I try to have a fully constrained assembly and then suppress the mates necessary to allow motion. When I'm finished I unsuppress the mates. It helps to label those specific mates "Door Open" or "Door Closed" when you go to unsuppress them.

I've also found that often the order of the mates can play a role. By performing the mates in a particular order you can also avoid SW misinterpetation.