[Al Skierkiewicz]

Moshe,
Sorry you took it that way, I did not intend it as anything but help. I am speaking from the standpoint of an FTC inspector.
From R5c 18. All mechanical fasteners (nuts, bolts, screws, etc.) of any length, any thread type, up to 0.375” (0.9525cm) diameter. The intent of this rule is to allow teams to use fasteners from any supplier that are substantially the same as TETRIX fasteners.
In the context of this wording, shaft collars are not considered fasteners(nuts, bolts, screws, etc.). I am merely trying to save you from facing this dilemma when you compete.
You may try asking on the Q&A. If they rule it as a fastener then you can proceed. The Q&A has ruled that threaded rod is a fastener.

R5c 17. Unlimited length Threaded Rod (also known as All‐Thread) not to exceed 0.375” (0.9525cm)
diameter (e.g. McMaster Carr Part #94435A317).