This is not an ordinary screw. The majority of the screws one comes across are single-start, meaning that there is a single groove wrapping around the screw body. However, this one has 5 such grooves. 

Multiple start screws have larger lead angle and larger thread lead (linear advancement per revolution) – to put it simply, this screw would go in 5 times as fast with each turn as an ordinary screw. We got it from the intestines of an industrial adjustable length mechanics element while working.

However, the accompanying nut was made from plastic which broke quickly. pwf asked a skilled lathe machinist he knew to turn and thread two new ones from bronze. He did it using a metal lathe, by manually turning the spindle by 72 degrees, without any CNC control. That’s the beauty of machining.