Hi,
Yes, I think the better solution would be to calculate the angles; my method was more of a workaround. You can still add points as rotation center points and use those instead of the cylinder objects.

Please check out the attached nod file.
I just found this node in my archives! I created it a while ago using points and vectors for three arms. It behaves more like a mechanism! You can add or remove arms easily by copying and pasting nodes and setting your desired pin joint points. Let me know if this is close to what you want.

Here is a tutorial that shows how to use the point picker node:
https://moi3d.com/forum/messages.php?webtag=MOI&msg=11887.1