ORIGINAL: Gray Beard
A lot depends on the type of plane. Anthony could use cooked pasta on his cub and get away with it. I have bent 4-40 all thread with 60 size stunt planes. There is a lot of material removed from all thread and it tends to bend very easily. Having ends hold is never a big problem.
+ 1
If using the "tube over the threaded rod" method, it is a good idea to glue the tube over the rod once you have got the lengths right. Way back when I used that method (I used Carbon tube) I used to mask the thread I wanted to keep and coat the rod with epoxy then slip the tube over the rod. Another guy I know uses CA and trickles it into the tube.
If Using the "Cooked Pasta" method - Capellini is ok for 2-56, Vermicelloni is best for 4-40 and Bucatini is best for light weight applications (Maybe an F3A plane)
[link=http://www.math.psu.edu/belmonte/spaghetti.html]Dynamic buckling of thin rods [/link]