If you want to realize symmetric stretch keeping keyway center no change and the length of smaller diameter shaft changes with stretch at same time, how will realize that?

1. Add Stretch for Step Shaft: 

Add stretch parameter and action for step shaft as the following picture shows. Therein to the bolded objects indicates the operation object of action.

Because the follow-up operation will not stretch step shaft by grips of this linear parameter, the grip’s number of linear parameter can be modified as “0”.

2. Add Linear Parameter for Keyways:

Set the base point position of line parameter as “Center” in order to realize symmetric stretch function.

3. Add Stretch Rightwards Action for Keyway

4. Realize Chain Action: 

Select “Distance” linear parameter and modify the chain action of prosperity from “NO” to “Yes” as the following picture shows.

Add Stretch Leftwards action for keyway as the following picture shows. Special Notes: Do elect “Distance” to linear parameter to stretch leftwards operation objects set. This is a necessary procedure of chain operation.

5. Test Dynamic Block: 

After dragging left grip not only the keyway will stretch bi-directionally and symmetrically but also smaller diameter shaft of step shaft will stretch automatically. This is chain action.

The realization of chain action has two important procedures: First, modify the property value of the parameter that need to happen linkage and modify the property of “chain action” from “NO” to “YES”. Second, select the parameter of objects that selected to linkage action to set.