Which constraint/parameter to use?

[R.Gerritsen4967]

I'm trying to achieve some behaviour in a dynamic block but I just can't figure out how to do it.

Please see the attached drawing.

The first block has a coincident constraint on the midpoint of the top of the web and the midpoint of the bottom of the faceplate. All the geometry is fully constrained.

For the second block the coincident constraint was changed to a colinear constraint and a move parameter was added to be able to move the faceplate. All the geometry is fully constrained.

What I want is to insert the block and then adjust the parameters for Height, Width an thickness.

Most of the time the center of the faceplate will be in line with the center of the web (like in block 1 in the attached drawing).

In this block I can change the parameters and the faceplate stays in the correct position.

However, sometimes I need the faceplate moved to the right or left.

To achieve this I have experimented with stretch or move actions, but they all have the nasty side-effect that I need to change the coincident constraint to something else. (see block 2 in the attached drawing)

This means that when I change the Width parameter of the block, the faceplate is not in-line with the web anymore. This in turn means that everytime I use the block and adjust the Width parameter, I need to adjust the faceplate position.

Is there something I can do about this to prevent the extra positioning action?

[Libbya]

Maybe this will suffice.  It doesn't give you a grip, but you can enter the offset from the center in properties and it will maintain that offset while accommodating changes to the other constraint values.  

[R.Gerritsen4967]

@Libbya,

Thanks for your answer!

Your approach is just like something I experimented with earlier, but unfortunately it still means some thinking when you insert the block and want the faceplate to be asymmetrical. (See block 3 in the attached drawing)

I have now incorporated a Visibility state in the block.

So I insert the block as a symmettrical and change the parameters.

If I need it to be asymmetrical, I change the visibility state. The 2nd state contains the original web plate and a new faceplate of which the parameters for Width and thickness are linked to the 1st state.

In the 2nd state there is a colinear constraint for the faceplate and a new horizontal constraint parameter for the overlap.

(See block 4 in the attached drawing)