Dynamic Technical Flex Duct Block Troubles

[jason.parras]

CAD Geniuses,

So I have this awesome Flex Duct LISP tool I found out there that automatically sizes its diameter and follows a polyline like a champion. It looks amazing, its quick, and I've never had it give me an issue. Naturally I wanted to use it on some mechanical work but my senior mechanical engineer is attached to his old flex block. I have, in every way, a superior tool that he refuses to use and by proxy, if I'm assisting in one of his projects, I cannot use it either. 

So I thought I'd try and update his flex blocks to be dynamic to speed up work and lessen headaches. As it stands, these blocks need to be scaled by a four digit decimal during insertion either upon their X or Y axis to increase or decrease their size to make them fit within the confines of a drawing. Infinitely more frustrating, they are set up to work on a 1 1/2" snap grid only. Accuracy beyond that and object snap are strictly forbidden... 

All I'd like to accomplish is making his set of blocks stretchable along their widths between a 6", 9", and 12" diameter and then their lengths editable through a 1.5" increment. I did my best to accomplish this but I am only able to change the diameter competently. When I attempt to adjust the length, the block simply moves left or right. I watched a few video tutorials on the scale or stretch selection requirements but they only seem to work on simple objects. The complexity of this accordion shape within the flex is confusing me.

So I tried my hand at constraints. The objects that were pumped out while using the scale and stretch actions with the attempted constraints look like something you'd find in one of Dante's 7 levels of hell. I would really like to get a handle on how to make this work not just in this but further creations. If you stuck with me through this wall of text, I thank you. Included is the laughable block I have made thus far. Any suggestions would be greatly appreciated. 

Jason

[Libbya]

The stretch action moves all vertices that are surrounded by the stretch window and does not move the vertices outside the stretch window.  Objects that connect vertices within and without the window are stretched.  Your stretch window surrounds the entire bunch of squiggles, so they move.  Regardless, if you were to surround just part of the squiggle, it would just get distorted.  I believe what you are looking for is the array action.

See the following screencast which gives a step-by-step on how to set it up. 

[jason.parras]

That was impressive. 

Thank you for taking the time to show me exactly how to set it up. I can see that the geometry of the flex limits it to being duplicated within the array only after its been stretched a certain distance. Hopefully this will be a fair compromise for the boss. I'll try my hand at it today when I have some free time and let you know what he thinks.

Thank you again!

[Libbya · Accepted solution]

You could do a separate array for each of the individual parts.  Here's a screencast showing how to array the individual parts.  

[jason.parras]

You continue to impress me with your comprehensive solutions and incredible commitment for what seems to be little self-gain. How can I thank you for your help?