Hi cjb53
I have done a chain in 2001. If you read other posts, they would warn you too, that making chains is a very arduous task.
My chain was stable, and I drove it with a sprokey, using cams on the teeth and driving a number of lins of the chain.
Although a link can in theory move along a curve using one planar connection, and two points on a curve, the points get confused, and the chain can collapse back on itself instead of 'snaking' out.
To prevent this I added another point on a 'limiting' curve attached to the previous link. This menans the links can still move reltive to one another, but not collapse.
With mechanisms I have found that if you drag too quickly the mechanism defies the constraints, so just be patient!!!
I do have some files, but I don't like sending them to all and sundry. If you need them I can send them, but only on the proviso they don't go into the public domain.
Best regards
Dave