My First Screw

Would this custom thread making by eye have been the usual way years ago?
The reason I ask I've had to make a bolt for an old clock fixing for a friend and the closest I could measure the thread came out at 3/16" dia, .75mm pitch and around a 50 degree profile.
I cant use the nut for a trial fit as the clock is 4 hours away.
I've made it but wont find out if it fits till the weekend when he takes it away for a try.
 
Someone started a thread a few of weeks back asking "what is a seat of the pants machinist" I think this is the answer:
I'll make each screw too long, cut the end into a tap (I file slots in the end), use the tap to make a perfect mating hole, cut the tap off (with its stressed and ruined threads), finish and polish the end, leaving the short screw with perfect, unused high threads. And it is perfectly mated to the hole.
All with no measurements!

Amazing!
 
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