Getting Solidworks to find the right assembly solution 1

[hoganh]

I've got an assembly with with hundreds of sub-assembly configurations. Each top level assembly is a configuration of the various sub-assembly configurations. In the top level assemblies I can move the interconnected 4-bar linkage configurations.

The problem I'm having is that Solidworks *sometimes* uses a second (mathmatically valid) solution, where the linkage has been toggled over-center, so it is in the improper position.

How can I force Solidworks to only find the proper solution (ie. a particular lever pointing in a general orientation)? I tried constraining a point on the linkage to a fixed planar surface but that didn't work.

Thanks!

 

[SBaugh]

Have you tried making an assembly sketch and useing that to control your assembly? Scott Baugh, CSWP
credence69@REMOVEhotmail.com

http://www.3dmca.com

http://home.insightbb.com/~scott.baugh/

*When in doubt always check the help*

 

[hoganh]

Yes, that's actually how I first created it (and it works), but I want to be able to move the mechanism by dragging the components (so I can check clearances). Components aligned to a sketch won't animate.

 

[Stoker]

This is a common problem, especially when the assembly includes tangent and angular constraints. There can be more than one valid solution to all the relations, so you don't always get the one that you want. There are a couple of things to try:

1) Use configurations to drive the animation instead of manually dragging components. This allows you to determine the point at which the assembly switches to the unwanted solution. You can then suppress the mates which are causing this solution and add new mates to force the assembly back to the correct solution. If your assembly only has a few positions at which you are at risk of having interference this is the way to go. I have found that when jumping from one configuration to another which is significantly different it is common for this problem to occur. If intermediate configurations are created which involve smaller changes you can often get to the second position without ever switching to the unwanted solution.

2) Change the mating scheme. The idea is to replace each angular mate with two distance mates. You need to ensure that the distances are always positive, so this may mean creating reference geometry outside the model to mate to. Eliminating angular mates will help a lot in eliminating this problem.