I have a drawing here with helicoil callout NAS1130-4F-15/C
I make this to be a 1/4-28UNF x 1.5Dia tangless free running but I do not know what the /C denotes! I have scoured the Emhart website to no avail Any ideas? .....Seasons Greetings all...
I think the F after the 15 may mean free running, though in NAS1130 there should be no letter for free running but you put an L after the thread size code for locking types.
Seems that "c" turned out to be "cleaned".
Thanx for all your help though.
FYI :-Emhart have a neat little piece of software that you can download to your desktop..Helicoil Bible!