Hi,
attached a version that as a limit on the thread length thus stopping it accidently running into the head.
I have set the limit at 1.5 x pitch of thread from the head.
So any input that is to big will automatically be corrected.

Wayne,
>>P.S: I am not going to say anything about threads missing in the nuts, because that has already been addressed. But... If I were to 3D print some nuts using this script, it would be another step, before the 3D build. Just thinking ahead....

If you wanted to 3D print a Screw & nut a thread cutter node for the nut could be done with an adjustable clearance by offsetting the thread profile.
I will have a look at adding that option.

Cheers
Barry