cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Showing results for 
Search instead for 
Did you mean: 

Losing Constraints in Assembly

Newbie

Losing Constraints in Assembly

We are assembling a model with a few different sub-assemblies in Creo 1.0. In the sub-assemblies on their own all mechanisms work fine. However when we put two sub-assemblies together in one assembly all mechanisms lose all restraints. Could anybody help us out asap?

3 REPLIES 3

Re: Losing Constraints in Assembly

Not seeing this, I would contact customer support with a high priority problem. They will walk you through it. It doesn't sound right but they will know if it is a known bug or if you need to do something before you open the assembly.

I don't use Mechanism much so I cannot help there. but if this is an urgent matter, PTC should be able to get you through it ASAP.

Re: Losing Constraints in Assembly

Peter,

Are you using Mechanism Constraints to place the sub assemblies in the top level assembly?
If you are using Insert, Mate, Align constraints most likely you will need to use a Mechanism General Constraint.
You can only use for example a insert and mate in one General constraint so you will need 2 General constraints to do the following (insert, mate, align). Would be
General Constraint (insert, mate)
General Constraint (align)

The reason for this is one side of the sub assembly is grounded out (not able to move) and the other side is free to move. If you attach the sub assembly to the toplevel assembly using the grounded side of the sub assembly, the assembly will lose it's motion ability.

Hope this helps,

Don Anderson

Re: Losing Constraints in Assembly

Peter,

You must assemble the two sub-assemblies as if they were all being put together at the top level. Whatever parts mate-up between the real sub-assemblies must be connected using the same formal rules as you would otherwise. Rigid joints should be used if the mating parts are rigidly secured to each other. Follow all proper rules and it should work fine. I’ve had hundreds of sub-assemblies go together without any issue using rigid and other joints types. It does sound unusual that all previously created joints in the sub-assemblies would become invalid, but this is a very difficult problem to help solve without having access to all the parts & assemblies. If it is not possible to share the files with us, PTC’s help desk will help solve this problem, though you’ll very likely need to share the file set with them.

Good Luck,

Chris

Announcements