Solidowrk Sub Assemblies

[CTRDevelopments]

Guys, I hope you can help, this is driving me crazy!

I have multiple assemblies for different parts, rod ends, wishbones etc etc. When I try to use assemble all these up into a 'final' assembly I can add them all fine. I make sure everythign is flexible, but when i try to add mates in the top level assembly, mates in the sub assemblies break. They are not highlighted as broken, but parts which as located as concentric fly all round the screen to positions which are useless.

For instance the ball in a rod end is concentrically aligned in the housing, and as a constrained maximum angular rotation of 9 degrees. This works fine. But when I assemble it into a wishbone and click move, the ball suddenly is able to move outside the housing.

Any help would be most appreciated

Cheers

Matt

 

[CorBlimeyLimey]

Any chance you could Pack & Go the assy to a ZIP file and post here for review?
It would be much easier and quicker than playing twenty questions trying to learn your mating scheme & possible problems.

 

[CTRDevelopments]

Hi

when you say 'Pack and Go' what exactly do you mean? I can zip it all up no problem and post it here if that is all required, or do I need to use a function/tool within solidworks?

cheers

Matt

 

[CorBlimeyLimey]

Regular zipping of the files with the assy will be fine.

I tend to suggest P&G now because so many people just post an assy without its component parts. P&G just makes it easier to ZIP all the associated parts.

 

[CTRDevelopments]

I have uploaded 'P&G'. Now the two black parts 'suspension mount 1 and 2' are mounted, for example to a flat plate. When I import this assembly, make it flexible and try to mate it to the flat plate, the mounts simply 'pull off' the tube?! Any thoughts?

Cheers

 

[CorBlimeyLimey]

I don't know what you did with Pack & Go, but you posted just the assy. The component parts are needed to enable opening the assy to check the mates.

http://help.solidworks.com/2011/Eng...roup/solidworks_explorer/hidd_copy_design.htm

 

[CTRDevelopments]

Sorry

I think I must have clicked on the wrong file when uploading! Please try this

Cheers

 

[SnowCrash]

You will need more restraints. Start by locating the spherical ball joints relative to the rods. I would also locate the pivots with full restraints.

--
Hardie "Crashj" Johnson
SW 2010 SP 4.0
HP Pavillion Elite HPE
W7 Pro, Nvidia Quaddro FX580

 

[CTRDevelopments]

Hi

I can try this, thats no problem, but this is just a simple example of the problem. Surly though if two cylinders ar econcentric in a sub assembly, they should always stay concentric?

 

[tristram]

I have not looked at your assembly, but you mentioned you made everything "flexible" and that doesn't sound right for what you are doing.

-Joe
SolidWorks 2009 x64 SP 5.1 on Windows XP x64
8 GB RAM - Nvidia Quadro FX1700

 

[CTRDevelopments]

I have made items like the rod ends flexible, such that the ball will rotate in the housing (The rod ends are a separate sub assembly, and my understanding is that you need to make the flexible to allow things to move). This may of course be the issue! It could always be a setting within my solidworks or something.

Cheers

 

[SnowCrash]

Start by UNfixing the fixed parts in the subassemblies and instead align them to the subassembly planes. Then in the main assembly start with the suspension mounts and position them per your design. Then you can let the subassemblies flex. In the un-flexed mode everything should be restrained. I think this will help.
"Fix your dog, fix your flat, don't fix your model"

--
Hardie "Crashj" Johnson
SW 2010 SP 4.0
HP Pavillion Elite HPE
W7 Pro, Nvidia Quaddro FX580

 

[CTRDevelopments]

Thanks

I will give this a go

 

[CTRDevelopments]

Snowcrash, thanks for this, I have unfixed things one item at a time, and it seems to be changing what happens, so I can only assume it is definately something to do with the problem. I will work my way down the list and hopefully by the end ot will be sorted. Thanks ever so much for the help!

 

[CorBlimeyLimey]

Theoretically, using the Fixed option for the first (and only the first) component in an assy, should not cause a problem. I have never had a problem in doing so. On the other hand using 3 mates (to the ref planes) in place of the Fixed should also not cause a problem ... unless one of them becomes unsuppressed.

After looking at your model, the under-defined mating scheme used in the sub-assys will have far more effect than fixed vs non-fixed. Limit mates can be temperamental at times, especially when Flexible assys are involved, and even more so when the flexible assy is under-defined.

 

[CTRDevelopments]

Cor, can you explain which bits in the sub assembly are underdefined? As if this may cause an issue in the future it would be better I get it right now!

Cheers

 

[CorBlimeyLimey]

Open each sub-assy and note which parts are prefixed with (-). Those parts are free to move. If it is not a needed Degree of Freedom (DoF), it should be constrained.

e.g. in Front Lower Wishbone Rear, the Three Eight Rod Ends are able to rotate. Add a parallel mate between a pair of ref planes to prevent that.

 

[CTRDevelopments]

chaps this does seem now much better. I have found though that i do need to make ALL the parts in a sub assembly 'float' or it doesnt work correctly when used in the main assembly. I am still having some trouble though, but it seems sometimes if I move the parts around suddenly the mates seem to be OK and it works?! I seem to get errors saying my main assembly is over constrained, for example when I mate a wish bone rod end to the mount on the tub, but there are no other mats connecting ANY of the wishbone to the tub? Any ideas on this? I am sure I have done something silly, but any thoughts would be most appreciated.

cheers

 

[CTRDevelopments]

Sorted now. It was a missed fixed part in a sub sub assembly!

Thanks for all the help