Rather interesting late afternoon/early evening.
Got lathe going for first time since last fall...just randomly making swarf to see how much I forgot, anyway, the usual mystery steel good in places, tons of chatter (to point of knocking sounds) in others, so figure hey, why not try inserts?
Well colour me impressed...and I have to conclude it was actually the metal since with the inserts there was still some chatter, way, way less but in certain sections (solid round, about 12" long, started out a bit over an inch in diameter) the chip definitely changed. Getting away from the area previous cut with HSS there was no chatter.
Got 4 variations on the chip by adjusting SFM and feed rate, a tight spiral maybe a 16th in diameter and nearly a foot long, a looser spiral about 3/8ths diameter and 3" long, one in-between those two in terms of diameter but much more tightly wound and around 6" in length (those were all, more or less, like springs) and small balls of a spiral wrapping around itself until a ball maybe a 1/4" in diameter was formed.
The longest pieces did not form more than one or two bird's nests and even near the chuck did not seem to want to wrap around either the work or the chuck jaws.
HSS on the same material certainly cut but definitely chip as opposed to spirals.
The bonus was I could feed at a greater rate as well as pick up the SFM...pretty much along the lines one could expect making comparisons across the various feed/speed charts.
Micro 100 (M100 Dex), generally SCLCR series, CCMT 21.5x (060202), Tungaloy/Toshiba if anyone cares, dry
The other noticeable thing was, and this could be wishful thinking, I could swear it sounded as if the motor and whole machine did not have to work as hard.
The finish was a bit rougher than with HSS but by varying the depth of cut a sort of happy medium could be found where less metal was removed but finish was about what HSS was AND if a shallow cut it was equal to about 120 grit shop roll after cutting with HSS. A close to "mirror" finish was possible but I am assuming it was more or less just rubbing (this was, after all, listed as general/roughing insert). The depth of cut was never as deep as with HSS but it maybe possible, I just did not want to push my luck tonight.