Al,
All GDC and Inspector responses come off as condescending, it's just the nature of the position, I think
Komodo,
You can use unlimited length threaded rod in your robot this year. You can use an unlimited number of nuts.
Andrew's response is slightly confusing. You can use lock nuts, or you can use two hex nuts tightened one against the other to lock both in place on the threaded-rod. Lock nuts come in different styles - the 'Kep nut' style that's in the kit has a built-in form of a lockwasher (that star-shaped thing attached); locking-thread or acorn-nut where the thread depth constricts and the nut jams onto the thread as it were; or the nylon-insert kind that has (oddly-enough) a nylon insert to keep the thread from vibrating/backing.
You are ALSO allowed loctite.
For the use you're describing, I'd use 1/4-20 nuts from McMaster by the hundreds... I'd also invest in a 1/4-20 NC die, a pair of vice-grips, and a 1" 6-point deepwell socket (when handheld, beats a die handle hollow for speed) to 'chase' the threads after you cut the rod. It'll help a LOT if you can dip the end of the allthread in a 1/4" deep capful of motor oil (used is fine).
I'd also use a fiberblade to cut that many rods. Get a 10" one and mount it in a tablesaw is how I'd do that, and use the fence for length.
I like the solution from Coach Norm, too, but for your application, it may just be a whole lot faster to use two nuts per side and tighten them against each other to lock them.
HTH!