Mobile crane blocks

[sscott9G46T]

Hi Can someone show me where i am going wrong on this block please. i want to be able to rotate the block from the centre of the pully the bottom section rotates find but the top part is supposed to be telescopic lengthening between two fixed points. (A) is fixed and should not be moving only rotating, (B) is the telescopic section that moved in and out as it rotates and (C) is a fixed point that should rotate but as you will see its not quite right. 

[Libbya · Accepted solution]

The Polar Stretch action has three steps in creating/modifying its selection set.  First is to set the stretch window, second is to set the items that are stretched, and third is to select the items that will rotate only.  You have the items in the stretch and the rotate selection sets reversed for the 'Polar Stretch' action.  Select 'Polar Stretch', right-click, select 'Action Selection Set>New Selection Set' and for the window remake it as it was, for the stretch select the part at C, and for rotate only select the part at A.  That should fix it.

[sscott9G46T]

excellent i knew it would be something simple but i just could not do it, thank you very much 😊

[ahmadpak5000]

Hi! It sounds like you're trying to create a rotating block with a telescopic section that functions correctly. Here are some pointers to troubleshoot:

1. Pivot Point: Ensure the rotation point for (A) is correctly set at the center of the pulley. The bottom section should rotate around this point.

2. Telescopic Mechanics: Check the constraints for (B) to ensure it can extend and retract smoothly while still maintaining its connection to both fixed points (A and C).

3. Fixed Rotation: For (C), ensure it is constrained to only rotate and not move in the radial direction. You might need to adjust its parent-child relationships or constraints.

4. Animation/Simulation Settings: If you're using software for this, verify that the animation settings allow for proper interaction between these components.