Dynamic crane block

[mecT8YGR]

I am trying to make a dynamic crane block with a move- and rotation parameter that should be chained with a stretch- and polar stretch parameter. I am having trouble with the right combination of the parameter and chains. The original block is multiple blocks put together, that I can't upload due to confidential information, so I have made a sketch of my issue.

The superlift radius is the main parameter and then the derrick angle. The derrick height and the polar stretch is being control by the derrick angle that is a fixed lenght. 

I hope it makes sense. I have attached a picture with some colours of the different parameter movements and also a DWG file. 

Thanks in advance.

/Mette

[Colin-Pearson]

I'm not sure, but I'm thinking you may not want a polar stretch on the main boom pendants.  Wouldn't the Polar Stretch only be set up along a particular direction?   If your main boom angle is changing, that might get weird.  I think you might be able to make it work if you are setting this up for a few fixed 85°, 83°, 80°, etc main boom angles ... that way since your boom tip would stay in place THEN maybe you could rotate the Polar Stretch so it always lies between the connection points at the tip of derrick and near the main boom tip.  If you're setting this up to have a variable main boom angle as well, that Polar Stretch may not work for you.  Just a thought, I have to hack my way through creating these blocks myself, so value here maxes out at $0.02 LOL.  I have a fantastic block done by others; I'll dig up and see how it was done.

[Colin-Pearson]

Couple things that might help folks solve this for you:

1 - Is the superlift fixed at a couple radius options or variable from Rmin --- Rmax?

2 - Are you trying to set this up for a variable main boom and/or derrick length as well?  

[mecT8YGR]

1 - yes the superlift is fixed at radius options with a Rmin - Rmax.

2 - I will make a block for each configuration so the length of the main boom and derrick is fixed and only the angle/radius.

For the Polar Stretch for the pendant at the main boom - I need to have the opportunity to make the radius with decimal so unfortunately I can't make the angle fixed.

I have work a bit more with the block and now it is only the superlift backet I can't get fixed to the tip of the derrick. 

[mecT8YGR · Accepted solution]

I just want to show my solution to my problem.

The solution was dimensional constraints together with geometric constraints - see attachment.

[Anonymous]

Is these what you need...