topic Bend with fixed Radius in Dynamic Blocks Forum

Bend with fixed Radius

Anonymous — Tue, 02 Feb 2021 17:04:38 GMT

I currently use the attached block...
In some case i need a "bend" with FIXED internal radius. (R1)
I woudl like to change by properties (no handles or fancy stuff) the linear parameter L1 keeping R1=15 even if L1 changes.... obviously i need to mantain the angular adjustment available (very important for me) and the hatch always associated to the external geometry.
The constraints keep the geometry aligned during the angular adjustment... but scaling or stretching the geometry does not have effect due to the consraints applied.
How can I fix that?
Thanks a lot!3DBIX

Bend with fixed Radius

Libbya — Tue, 02 Feb 2021 17:15:32 GMT

Considering you are using constraints for everything else in the block, the obvious choice for L1 is to use a linear dimensional constraint instead of a linear dynamic parameter and action.

Re: Bend with fixed Radius

Anonymous — Tue, 02 Feb 2021 19:08:02 GMT

I've just tried but the behavior seems to have some problem... for sure the problem it's me. 😄

Re: Bend with fixed Radius

tim_crouse — Wed, 03 Feb 2021 19:47:55 GMT

Take a look at the attached file, it may help you.

-Tim C.

Re: Bend with fixed Radius

tim_crouse — Wed, 03 Feb 2021 19:56:48 GMT

Sometimes you may find it better to avoid the constraints when dealing with arcs and handle the math via scaling then add other controls to tweak other parts of the geometry to correct for the scaling.

This may be a more relaxed approach than you were hoping for. But it's a mixed bag in not trying to over constrain the block which can make it clumsy to use.

-Tim C.

Re: Bend with fixed Radius

Anonymous — Thu, 04 Feb 2021 11:45:52 GMT

Very interesting.. the only loss by now is the insert point that in your solution needs to be in the center of rotation.
But...
I've changed a little bit your block and without the scalable inner diameter i can have the ins point on the inner corner... locking the inner diameter to the one i want. (10)

I share it here.

My question now is ... how can i handle the duct setting it's REAL width ?? (without making a fake linear parameter and a lookup table)
In the attached file you see the block at it's minimum dimensions 20 is the real width but the overall distance to the center is 30 and it's the only one i can modify to change the dim. of the duct.
Hoping to find a solution i THANK YOU ALL ... a lot.
Bix

PS: The grey dashed Circle you have in the block that is useful to keep locked the center.... WHY it disappear form inside to the outside the block? what property did you used?

Re: Bend with fixed Radius

Libbya — Thu, 04 Feb 2021 15:27:17 GMT

Changing the arc length while maintaining the arc radius is one of the few times that I find constraints are actually useful. Here's how to fix the constraints version:

Re: Bend with fixed Radius

tim_crouse — Thu, 04 Feb 2021 22:32:34 GMT

Is this a little closer, or in the wrong direction?

Re: Bend with fixed Radius

Anonymous — Fri, 05 Feb 2021 17:49:35 GMT

Hi Libbya thanks a lot for the help...

The solution you get is very similar on what i need, i wonder how i can keep the insertion point in the midpoint of the horizontal line and the rotation control in the midpoint of the vertical one....
I'm trying to think how.... and the only idea i have is to move a basepoint but it cannot be related to a constraint (G1 in the block attached) ....with a multiplier 0.5 i thought would work... but can not associate a move action to a constraint...so...now I have no idea how to get those ideas.

Re: Bend with fixed Radius

Libbya — Fri, 05 Feb 2021 17:54:15 GMT

AFAIK you cannot control constraint grip points in the way you describe but I am not the best at constraints.