In Reply to: Re: Head Bolts/Studs posted by Steve Dabrowski on April 26, 2022 at 17:15:50:
I knew I was out on a flimsy limb with the chronology of the changeover - should have checked before typing.
Here is some manufacturing minutia for you Steve. Just about every mass produced externally threaded fastener made today (and for many decades past) has rolled threads. Its faster to produce and and it cold works the steel which relieves internal stress and makes the fastener a tiny bit stronger. Rolled or machined the thread fit tolerance is the same - for most commercial fasteners that is class 2A fit. Thread chasers as opposed to taps and dies are forming rather than cutting tools for the express purpose of not changing the thread fit.
TOH