Yes, I know what the tap is, I have tons of them in my workshop.
I guess my question is - if it is generally understood that a nut-and-bolt pair was not uncommon in the early 16th century, then this approach can be viable. However, generally speaking, screws on weapons became common in the 18th century - usually attaching the guard to the pommel.
In reality I might make two versions, one with the screw, and the other one with the spring.