hey Kev, be careful, "parting between centers" is just not a thing. much like sawing off a limb sitting on the outside..first thing I thought
! there's a reason you didnt see it on line!!!
making a grove for a saw to work in is WAY different than parting, and even so, I wouldn't consider taking say, a 2" dia held between centers down to 1/4, anywhere on a 13" piece, yikes. I dont know how far out you are parting, but imagine if it went bad down at the bottom of the cut and bound up, wrenching the part out of the chuck and jackknifing like a tractor trailer.
THE THING THAT WOULD "CATCH THE PART" MIGHT BE YOUR FACE. (along with the flying shrapnel of the parting blade end going 120 MPH) and it wouldnt be in a predictable trajectory, could ricochet anywhere. a busted parting blade is one of the more dangerous things a lathe can spit at you.
sorry if you already understood all this, but just to make it clear to anyone else looking, felt the need to get that out there.
I've hand hacksawed off lots of parts spinning on a lathe, but much smaller stuff, and NEVER between centers. for 2" dia. that doesnt seem like such a great idea even well supported single side near the chuck. its better to start a grove 20% deep max if between centers, take it off the lathe and saw it, put it back on the lathe. cheers, and work safe!