There was a discussion on another thread about what is available for small chains suitable for N scale. I wasn't sure if I should start this thread in "Weathering, Detailing, and Scratchbuilding" or here but I know that the moderators will take care of this.
I made a comparison of the chains I have in my parts bin. I originally posted this info on the Atlas forum but in case that gets taken offline, I'll post this info here.
The above photo shows a standard inch and an N scale (with 6" divisions) rulers for reference.
From the closest to the ruler:
TrainCat 72 LPI "chain". I actually counted it to be closer to 82 LPI. It is not a real chain. It is a flat photoetched piece.
Traincat 52 LPI chain. I counted it to be 46 LPI. This is the finest true chain I have ever found.
Unknown source 38 LPI chain. I seem to recall that it was manufactured by one of the model railroad manufacturers - I just don't recall which one.
EDIT: Max Magliaro in this post provided the following info: the 38 LPI chain you had on your other info page that you linked to from here, I believe is http://www.builders-in-scale.com/bis/parts-chain.html (the black 40 LPI chain).
The Builders In Scale 40 LPI is the smallest stuff I have. I can certainly believe that it actually only measures out to 38 LPI.Silver 30 LPI chain. This is a chain from an old necklace which was no longer being used. HINT: look at old jewelry and you might find a good source of fine N scale chain.
22.5 LPI chain. From Clover House.
21 LPI chain with flat links. From Clover House.
I also found another (even finer) "chain". It isn't even a real chain but it sure looks convincing. DKS used it on one of his models.
Dave states: The chain is actually a piece of beading needle, which is very fine stainless wire twisted tightly.
The construction of that piece of rolling stock is fully described in
http://therailwire.net/forum/index.php?topic=19637.0