Modeling Straight Cable with Adaptable Length

[dean.cheng99]

Hi, I am trying to connect two points giving the appearance of a tensioned string or cable that can stretch. The two points are on on two components that move relative to each other. I tried connecting the components with a 3D line and generating a pipe but as the components move the pipe remains stationary and does not adapt to the changing point positions. If I make the pipe a component and connect the ends to the other components with a ball joint, the pipe keeps the same length  which over constrains the assembly. Is there a simple way to render a straight cord that adapts to motion of an assembly without hindering it?

Thanks,

[jhackney1972]

Is this what you had in mind?  See Screencast

[dean.cheng99]

Yes, that is it.  I'd like to get my pipe length to adapt to the change in distance between two components as you had demonstrated. I tried to recreate your example. I created three components. The first block is grounded. The second is a copy/paste new of the first. The third component is a line sketched off to the side, then created a pipe following the line. I then made a rigid connection between the first block and the pipe.  At the other end of the pipe I made a sliding connection to the other block. But when I moved the second block, the end to the pipe is stationary. I dragged the block directly and also tried it by editing the sliding joint. I cannot get the pipe to adapt. I must be missing a step. 

Thanks for the quick reply.

[jhackney1972]

In my example the Slider joint distance value is assigned to a parameter which is also is assigned as the length of the pipe path.  Change the slider movement changes the pipe length  so they stay together.

[dean.cheng99 · Accepted solution]

I did get the example to work. In the Edit Joint dialog box I noted the Offset Z parameter name I found by hovering the cursor over the value. In my case it was "d156". I then went into the sketch for the rod and inserted "d156" for the length dimension. Now when I drag the arrow for the offset Z joint alignment, the rod length changes.

I tried repeating the example again for practice but I ran into a stumbling block. The rod length dimension placeholder won't take it the parameter (different id this time). I suppose that when I was creating the rod, the slide joint didn't exist. I'm not sure how I was able to do it the first time.

[jhackney1972]

Since you have solved your issue, please post an example and explanation of that solution, please.

[dean.cheng99]

Thanks jhackney for your clever idea. It doesn't solve my immediate problem with line length adaptation when I run a    motion study but it is a help for model editing.

I did come up with a cumbersome workaround. I made a multi-segment telescopic mast composed of 10 pipes components and 9 sliders all under the umbrella of a single component. The downside is that the length ratio is limited by the coarseness of the segmenting. Also if I have a lot of the units, the animation of the assembly gets bogged down.