I was sure this had been covered somewhere, but searching the forum for "chain" mainly produces info on IK chains. There doesn't appear to be a properly working example anywhere in my library either.

When rigging a chain, there's an inherent problem in that one rotation centre per joint won't do. If the chain extends along the X axis for example, Y rotation requires the joint centre to be in a different place than does Z rotation.

The answer would seem to be to place the centre to suit one rotation axis, then use ERC to compensate for the other. I've tried it, but it's more difficult than it first appeared. Some of the ERC linkages apparently need to respond to the absolute value of the rotation angle, and I can't work out how to do that.

ERC gurus, your input would be welcome.

If you aren't an ERC guru and don't have the faintest idea what I'm banging on about, load up a posable chain from your library and try both rotation directions while zoomed in on the link in question. In one direction at least, the link will pass through the adjacent one. In some examples neither direction works properly, but we can discount those... On the other hand, if you have a chain that works properly in both directions, let me know which one it is so I can see how it was done. ;)