driving constraints in assemblies

[tmox]

I am new to Inventor. I have created many assemblies and constrained them fully and in the case of things like cylinders, have been able to "drive constraints" to operate the cylinder in the assembly.
Well i must have gotten lucky on the first large assembly i did because i haven't been able to pull off this trick since.
I have started to create a library of cylinders, made up of at least 2 parts (cylinder/rod) constrained so that i can manipulate the rod (extend/retract). This will be put into another subassembly at which point i loose the ability to operate the cylinder. This sub will get put into the main assembly. So basically, the point at which i AM able to operate this cylinder is nested 3 levels down in the assembly tree.
Can someone tell me the (simple) thing that i am doing wrong. I have the cylinder body grounded (so that the rod moves and not the cylinder) and have made all the parts adaptive back and forth trying to get this to work again.
Please help!!! I WOULD like to operate several different items in the main assembly level.

 

[testy]

You will most likely have to have the components that you want to move constrained in the top assembly. When you insert an assembly such as the piston and rod they will move as one entity, not independently of each other. Try inserting and constraining first the Rod and then the Piston into the main assembly.

HTH

Ray Havermahl
Independent Engineering Labs

 

[tmox]

i realize that i could probably constraint each component of the cylinder in the top level. If i have 5 or 6 different cylinders in the top level all with different strokes, all with 3 or 4 components (end effectors) and i need to ............change brands, change strokes, (cylinder length will change) etc. it would be much nicer if i could just "replace component" and update without having to check a myriad of constraints.

 

[autocol]

what you need to do is make your rod and cylinder sub-assemblies adaptive.

right click on the sub-assembly, select adaptive in the context menu, and you'll be able to drive the constraint that you can't at the moment.

that's all you have to do to allow assemblies to drive within other assemblies.

note this, however. if you place more than one instance of an assembly into a parent assembly, and drive one, they ALL will drive. if you want to drive them independently of each other you'll need to make copies of them. you can also only mark one instance of an assembly adaptive. inventor enforces this to prevent you from accidentally adapting a single file in multiple places, which would require some sort of quantum file that had many states simultaneously

hope that helps.

col.