My buddy is an experienced aircraft mechanic. He states it is vital to lap and polish freshly made flares to remove any stress risers that can lead to splitting at the flare. I rarely do this, and have not seen any of my flares split. He either apparently has or its an industry standard training protocol.
I do tighten and loosen the jam nuts half a dozen times to better seat them. They tend to get tighter and turn in farther until the 3rd or 4th tightening cycle..
I'm a non-practicing A&P, and concur with your buddy. For aviation applications. Aircraft endure far more sustained cyclical vibration, particularly prop driven piston engine aircraft. Risers will turn into cracks in no time, anywhere (ever wonder why jet liners have rounded window corners as opposed to 90*). In my decade as a general aviation mechanic, I saw my share of brake lines with cracked flares having been properly lapped. I was trained to, harangued and nagged to and so just always did it. If there are any imperfections in the flare, they may last 10 years on the calendar, but probably less than 100hrs in the air.
