Excuse me signor h0ughy,

but if you calculate using the measurements, that I braved the cold, spiders and other dangers of the deep southern winter night to take for you, it will be apparent that Laurie is semi correct. 5.05 mm OD is not 8mm, but the pitch of 32TPI equates to what I measured. I am assuming that my LX90 tripod is the same size as yours. If you go to your local bolt shop and give them the O/D and 32TPI they should be able to find a couple for you. Here's a chart which lists US Sizes from what I measured I would say 10 Gauge 32TPI (UNF)
http://www.sizes.com/tools/thread_american.htm