I dunno.
On the time sheet, it says "chase threads" for 4 minutes each with 10 passes of 18tpi 11/16" length at 77 rpm. And no time to change bits or take measurements. At 10 passes in 4 minutes, that's a pass every 30 seconds. The lathe alone will take 11/16 x 18 = 12 revolutions to cut each pass. At 77 rpm, thats about 10 seconds just for cutting with no lead-in or waiting for the thread dial or disengaging the half nut, or cranking out the tool, or backing off for another pass or taking any measurements.
I do most of my threading at 70 rpm. For most lathes 18tpi is an even number thread that can only be cut on two locations on the thread dial at opposite extremes (say marks 1 & 3 or 2 & 4). It takes up to 20 seconds to transition to one of those numbers which is an average of 10 seconds depending on how lucky you are. It's impossible to get 0 unless the lathe is stopped or you deliberately crank the carriage back to hit zero which means you have extra empty space to thread at the beginning of each pass.
In other words, in an ideal world, it takes 20 seconds to cut per pass. Leaving only 10 seconds to disengage, retract, rewind, take a measurement, dial in the next pass, and engage the half nut.
Is it possible? Ya, it's possible. So it survived the sniff test. But it requires robotic precision that only CNC can do. Mere mortal human beings can only dream of doing that.
