Dynamic block help - relationships not maintained

[Anonymous]

Hi guys. After a bit of help. Just come onto AutoCad from Inventor/SW and loving the dynamic blocks....but I have hit a stumbling block (pardon the pun!)

I have made a simple block, (a panel) which I want to be able to stretch vertically and horizontally. The panel is showing some internal ribbing, which I want to remain at set distances (eg 40mm down from top etc)

I have tried adding linear dimensions but these seem to be ignored when stretching vertically.

Can someone have a look please.

[Libbya]

I know that inventor is big on the use of constraints, but in dynamic blocks they cause more issues than good, 99% of the time in dynamic blocks.  Most of the time the desired block can be made more easily using dynamic parameters/actions and the result functions more consistently, uses less memory, reacts more quickly, etc...  You might want to get out of the habit of using constraints within dynamic blocks, get used to using the dynamic parameters/actions and reserve the constraints as a last resort if dynamic parameters/actions cannot accomplish alone what you need to accomplish (very rare).  

In this case, the block works fine if you simply delete all the completely unnecessary bits. 

[Anonymous]

Thanks. I was wondering if it was a conflict. I actually tried it first without constraints... And it did work in a way.... (stretching of the panel vertically worked) however the ribs didn't keep their position... Eg if you stretched it up 1000mm, then the distance to the top rib also increased 1000mm.




The intention is to have the 3 ribs at given set points (40mm from the top & 60mm from the bottom etc)




Hope that makes sense

[Libbya]

If you want set distances and three center ribs, then you should draw it that way in block editor.  The way your file is drawn shows 2 center ribs (not 3) and it is drawn with the center of the top rib 727 units (millimeters) from the top of the block.  The center of the bottom rib is 796 units from the bottom of the block.  I don't see how that relates to the 40 and 60 you say you desire.  If you want to maintain the distance of the top rib from the top of the block and you want to maintain the distance of the bottom rib from the bottom of the block, then the bottom of the stretch window should be between the two ribs (not below the bottom one).  You should not include the bottom rib or the side vertical lines that are below the bottom rib in the stretch selection set.  

[Libbya]

The functions of the stretch window and selection set are fairly simple but important to understand in order to have stretch actions work correctly.  If the stretch window surrounds a vertex of an object in its selection set, it will stretch that vertex based on the change in the associated parameter (and modified by the distance modifier and angle offset of the stretch action).  If an object in the selection set is either completely inside or completely outside the stretch window it will be moved rather than stretched.  Hope that helps.  

[Anonymous]

Yea that makes sense actually. I did wonder if it was to do with my selection.

I'll give it a try Monday. Thanks guy's