topic Re: Further help with regards to stretched Dynamic Block in Dynamic Blocks Forum

Further help with regards to stretched Dynamic Block

IHPBusiness94 — Tue, 27 Sep 2022 13:21:17 GMT

Hello,

I'm trying to complete this dynamic block for work but I'm stuck on this issue, the diagonals are supposed to stay 1" wide and be perpendicular to the end (So a rectangle with it's base at an angle). I was wondering if anyone had a viable solution, I've attempted to constrain it amongst other small things but I've recently only been reintroduced into Dynamic Blocks.

Re: Further help with regards to stretched Dynamic Block

IHPBusiness94 — Thu, 29 Sep 2022 18:52:54 GMT

Wanted to give this a bump, I'm really hopeful and grateful for any help in solving this. I've been doing mixtures of parameters and constraints and not getting the result I've been wanting. Hoping to see what the pros have to say.

Re: Further help with regards to stretched Dynamic Block

h_s_walker — Fri, 30 Sep 2022 08:20:35 GMT

Have you tried using dimensional constraints on the angles? See the link below

About Applying Dimensional Constraints | AutoCAD 2020 | Autodesk Knowledge Network

Re: Further help with regards to stretched Dynamic Block

IHPBusiness94 — Fri, 30 Sep 2022 16:31:46 GMT

From my attempts, the constraints made the block more unstable, and often clashed with the vertical and horizontal stretching features, most notably shrinking the block after a stretch, and inputting a width for it to stretch to while under constraints

Re: Further help with regards to stretched Dynamic Block

tim_crouse — Tue, 04 Oct 2022 14:17:23 GMT

See attached for an example. My assumption was you were trying to keep the trusses at 45°. As such, I took a single central action approach.

A Tip for something like this. Sometimes as with basic engineering, it is best to break the problem into a simple free-body diagram. Once you get the basic geometry working you can then start to expand on the idea. My initial onset was a single horizontal plane with (2) lines at 45° opposite to each other.

Best Regards

-Tim C

Re: Further help with regards to stretched Dynamic Block

IHPBusiness94 — Tue, 04 Oct 2022 15:02:30 GMT

I apologize, I feel I should have provided more details.

The issue I'm having is keeping the diagonals 3" off from the end of the column and 1/8" from the center of the beam (For the "V" shaped diagonals). I need them to be 1" thick and for the top to maintain their shape. The truss will array when it's stretched upward. The issue is, as seen in my block, that when it's stretched horizontally, the diagonal end doesn't stay 90 degrees to the other diagonals, and I'm unsure if it remains 1" thick.

When using constraints, it has a habit of making the block more chaotic, especially when typing in your desired width or shrinking the block

I deeply appreciate the help that's being provided

Re: Further help with regards to stretched Dynamic Block

tim_crouse — Tue, 04 Oct 2022 15:49:18 GMT

I am not tracking the perceived issue of the required offsets. Not to say the example provided is the only way, but . .. in that example where ever you place the ends of the trusses is where they will remain, meaning any initial offset established will be maintained.

The trusses do not get wider or narrow as the rack size is adjusted. They are maintained at a constant width as the VERTICAL linear control is stretched.

-Tim C.

Re: Further help with regards to stretched Dynamic Block

j.palmeL29YX — Tue, 04 Oct 2022 17:55:01 GMT

The horizontal stretching is not an unsolvable problem, if you use constraints (see attached block pa - test). But then I fail at the vertical array and therefore can't suggest a solution either.

Perhaps you can use for the vertical stretching (the array) an other "strategy" (?).

Re: Further help with regards to stretched Dynamic Block

tim_crouse — Tue, 04 Oct 2022 18:41:47 GMT

I see the deformation at the end you are referring to.

I will take another look to see if I can get the object to rotate as it stretches.

Best Regards

-Tim C

Re: Further help with regards to stretched Dynamic Block

tim_crouse — Tue, 04 Oct 2022 20:07:45 GMT

This is a bit better

If you want to practice your geometry this would be a fun challenge, but as it is aI cheated and used constraints.

Best Regards

-Tim C.

(ps sorry for all the typos in the notes, was in a hurry)